Index: dll/3rdparty/libpng/docs/ANNOUNCE =================================================================== --- dll/3rdparty/libpng/docs/ANNOUNCE (revision 56925) +++ dll/3rdparty/libpng/docs/ANNOUNCE (working copy) @@ -1,5 +1,5 @@ -Libpng 1.5.2 - March 31, 2011 +Libpng 1.5.12 - July 11, 2012 This is a public release of libpng, intended for use in production codes. @@ -8,55 +8,31 @@ Source files with LF line endings (for Unix/Linux) and with a "configure" script - libpng-1.5.2.tar.xz (LZMA-compressed, recommended) - libpng-1.5.2.tar.gz - libpng-1.5.2.tar.bz2 + libpng-1.5.12.tar.xz (LZMA-compressed, recommended) + libpng-1.5.12.tar.gz + libpng-1.5.12.tar.bz2 Source files with CRLF line endings (for Windows), without the "configure" script - lpng152.7z (LZMA-compressed, recommended) - lpng152.zip + lpng1512.7z (LZMA-compressed, recommended) + lpng1512.zip Other information: - libpng-1.5.2-README.txt - libpng-1.5.2-LICENSE.txt + libpng-1.5.12-README.txt + libpng-1.5.12-LICENSE.txt -Changes since the last public release (1.5.2): +Changes since the last public release (1.5.11): - More -Wshadow fixes for older gcc compilers. Older gcc versions apparently - check formal parameters names in function declarations (as well as - definitions) to see if they match a name in the global namespace. - Revised PNG_EXPORTA macro to not use an empty parameter, to accommodate the - old VisualC++ preprocessor. - Turned on interlace handling in png_read_png(). - Fixed gcc pendantic warnings. - Handle longjmp in Cygwin. - Fixed png_get_current_row_number() in the interlaced case. - Cleaned up ALPHA flags and transformations. - Implemented expansion to 16 bits. - Fixed mistake in the descriptions of user read_transform and write_transform - function prototypes in the manual. The row_info struct is png_row_infop. - Corrected png_get_current_row_number documentation - Fixed the read/write row callback documentation. - This documents the current behavior, where the callback is called after - every row with information pertaining to the next row. - Fixed scripts/makefile.vcwin32 - Updated contrib/pngsuite/README to add the word "modify". - Define PNG_ALLOCATED and other attributes to blank when _MSC_VER<1300. - ifdef out mask arrays in pngread.c when interlacing is not supported. - Added a hint to try CPP=/bin/cpp if "cpp -E" fails in scripts/pnglibconf.mak - and in contrib/pngminim/*/makefile, eg., on SunOS 5.10, and removed "strip" - from the makefiles. - Fixed a bug (present since libpng-1.0.7) that makes png_handle_sPLT() fail - to compile when PNG_NO_POINTER_INDEXING is defined (Chubanov Kirill) - Don't include standard header files in png.h while building the symbol table, - to avoid cpp failure on SunOS (introduced PNG_BUILDING_SYMBOL_TABLE macro). + Removed scripts/makefile.cegcc from the *.zip and *.7z distributions; it + depends on configure, which is not included in those archives. + Changed "a+w" to "u+w" in Makefile.in to fix CVE-2012-3386. Send comments/corrections/commendations to png-mng-implement at lists.sf.net (subscription required; visit https://lists.sourceforge.net/lists/listinfo/png-mng-implement -to subscribe) or to glennrp at users.sourceforge.net +to subscribe) +or to glennrp at users.sourceforge.net Glenn R-P Index: dll/3rdparty/libpng/docs/CHANGES =================================================================== --- dll/3rdparty/libpng/docs/CHANGES (revision 56925) +++ dll/3rdparty/libpng/docs/CHANGES (working copy) @@ -1,5 +1,4 @@ #if 0 -libpng_changes(){ /* CHANGES - changes for libpng Version 0.2 @@ -15,7 +14,7 @@ fixed some bugs in writer interfaced with zlib 0.5 added K&R support - added check for 64 KB blocks for 16 bit machines + added check for 64 KB blocks for 16-bit machines Version 0.4 cleaned up code and commented code @@ -74,7 +73,7 @@ Version 0.85 [December, 1995] added more medium model code (almost everything's a far) added i/o, error, and memory callback functions - fixed some bugs (16 bit, 4 bit interlaced, etc.) + fixed some bugs (16-bit, 4-bit interlaced, etc.) added first run progressive reader (barely tested) Version 0.86 [January, 1996] @@ -180,7 +179,7 @@ Fixed serious bug with < 8bpp images introduced in 0.95 Fixed 256-color transparency bug (Greg Roelofs) Fixed up documentation (Greg Roelofs, Laszlo Nyul) - Fixed "error" in pngconf.h for Linux setjmp() behaviour + Fixed "error" in pngconf.h for Linux setjmp() behavior Fixed DOS medium model support (Tim Wegner) Fixed png_check_keyword() for case with error in static string text Added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul) @@ -197,18 +196,20 @@ Added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P) Minor corrections in libpng.txt Added simple sRGB support (Glenn R-P) - Easier conditional compiling, e.g. define PNG_READ/WRITE_NOT_FULLY_SUPPORTED; + Easier conditional compiling, e.g., + define PNG_READ/WRITE_NOT_FULLY_SUPPORTED; all configurable options can be selected from command-line instead of having to edit pngconf.h (Glenn R-P) Fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P) Added more conditions for png_do_background, to avoid changing black pixels to background when a background is supplied and no pixels are transparent - Repaired PNG_NO_STDIO behaviour - Tested NODIV support and made it default behaviour (Greg Roelofs) + Repaired PNG_NO_STDIO behavior + Tested NODIV support and made it default behavior (Greg Roelofs) Added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler) Regularized version numbering scheme and bumped shared-library major - version number to 2 to avoid problems with libpng 0.89 apps (Greg Roelofs) + version number to 2 to avoid problems with libpng 0.89 apps + (Greg Roelofs) Version 0.98 [January, 1998] Cleaned up some typos in libpng.txt and in code documentation @@ -1778,7 +1779,7 @@ Removed AC_FUNC_MALLOC from configure.ac Work around Intel-Mac compiler bug by setting PNG_NO_MMX_CODE in pngconf.h Change "logical" to "bitwise" throughout documentation. - Detect and fix attempt to write wrong iCCP profile length. + Detect and fix attempt to write wrong iCCP profile length (CVE-2006-7244) Version 1.0.21, 1.2.13 [November 14, 2006] Fix potential buffer overflow in sPLT chunk handler. @@ -2361,7 +2362,7 @@ Version 1.4.0beta73 [August 1, 2009] Reject attempt to write iCCP chunk with negative embedded profile length - (JD Chen) + (JD Chen) (CVE-2009-5063). Version 1.4.0beta74 [August 8, 2009] Changed png_ptr and info_ptr member "trans" to "trans_alpha". @@ -2935,7 +2936,7 @@ PNG_INTERLACE transform and to get the number of rows in the current pass. A new test program, pngvalid.c, validates the gamma code. - Errors in the 16 bit gamma correction (overflows) have been corrected. + Errors in the 16-bit gamma correction (overflows) have been corrected. cHRM chunk testing is done consistently (previously the floating point API bypassed it, because the test really didn't work on FP, now the test is performed on the actual values to be stored in the PNG file so it @@ -3149,8 +3150,8 @@ in version 1.5.0beta36 but is not noted in the CHANGES. Similarly, it was changed from png_charpp to png_const_bytepp in png_set_iCCP(). Ensure that png_rgb_to_gray ignores palette mapped images, if libpng - internally happens to call it with one. - Fixed a failure to handle palette mapped images correctly. + internally happens to call it with one, and fixed a failure to handle + palette mapped images correctly. This fixes CVE-2690. Version 1.5.1beta02 [January 14, 2011] Fixed a bug in handling of interlaced images (bero at arklinux.org). @@ -3208,9 +3209,9 @@ pngvalid contains tests of transforms, which tests are currently disabled because they are incompletely tested. gray_to_rgb was failing to expand the bit depth for smaller bit depth images; this seems to be a long - standing error and resulted, apparently, in invalid output. The - documentation did not accurately describe what libpng really does when - converting RGB to gray. + standing error and resulted, apparently, in invalid output + (CVE-2011-0408, CERT VU#643140). The documentation did not accurately + describe what libpng really does when converting RGB to gray. Version 1.5.1beta10 [January 27, 2010] Fixed incorrect examples of callback prototypes in the manual, that were @@ -3227,7 +3228,7 @@ Version 1.5.1beta11 [January 28, 2011] Changed PNG_UNUSED from "param=param;" to "{if(param){}}". Corrected local variable type in new API png_process_data_skip() - The type was self-evidently incorrect but only causes problems on 64 bit + The type was self-evidently incorrect but only causes problems on 64-bit architectures. Added transform tests to pngvalid and simplified the arguments. @@ -3285,7 +3286,616 @@ to avoid cpp failure on SunOS (introduced PNG_BUILDING_SYMBOL_TABLE macro). Version 1.5.2 [March 31, 2011] + No changes. +Version 1.5.3beta01 [April 1, 2011] + Re-initialize the zlib compressor before compressing non-IDAT chunks. + Added API functions (png_set_text_compression_level() and four others) to + set parameters for zlib compression of non-IDAT chunks. + +Version 1.5.3beta02 [April 3, 2011] + Updated scripts/symbols.def with new API functions. + Only compile the new zlib re-initializing code when text or iCCP is + supported, using PNG_WRITE_COMPRESSED_TEXT_SUPPORTED macro. + Improved the optimization of the zlib CMF byte (see libpng-1.2.6beta03). + Optimize the zlib CMF byte in non-IDAT compressed chunks + +Version 1.5.3beta03 [April 16, 2011] + Fixed gcc -ansi -pedantic compile. A strict ANSI system does not have + snprintf, and the "__STRICT_ANSI__" detects that condition more reliably + than __STDC__ (John Bowler). + Removed the PNG_PTR_NORETURN attribute because it too dangerous. It tells + the compiler that a user supplied callback (the error handler) does not + return, yet there is no guarantee in practice that the application code + will correctly implement the error handler because the compiler only + issues a warning if there is a mistake (John Bowler). + Removed the no-longer-used PNG_DEPSTRUCT macro. + Updated the zlib version to 1.2.5 in the VStudio project. + Fixed 64-bit builds where png_uint_32 is smaller than png_size_t in + pngwutil.c (John Bowler). + Fixed bug with stripping the filler or alpha channel when writing, that + was introduced in libpng-1.5.2beta01 (bug report by Andrew Church). + +Version 1.5.3beta04 [April 27, 2011] + Updated pngtest.png with the new zlib CMF optimization. + Cleaned up conditional compilation code and of background/gamma handling + Internal changes only except a new option to avoid compiling the + png_build_grayscale_palette API (which is not used at all internally.) + The main change is to move the transform tests (READ_TRANSFORMS, + WRITE_TRANSFORMS) up one level to the caller of the APIs. This avoids + calls to spurious functions if all transforms are disabled and slightly + simplifies those functions. Pngvalid modified to handle this. + A minor change is to stop the strip_16 and expand_16 interfaces from + disabling each other; this allows the future alpha premultiplication + code to use 16-bit intermediate values while still producing 8-bit output. + png_do_background and png_do_gamma have been simplified to take a single + pointer to the png_struct rather than pointers to every item required + from the png_struct. This makes no practical difference to the internal + code. + A serious bug in the pngvalid internal routine 'standard_display_init' has + been fixed - this failed to initialize the red channel and accidentally + initialized the alpha channel twice. + Changed png_struct jmp_buf member name from png_jmpbuf to tmp_jmpbuf to + avoid a possible clash with the png_jmpbuf macro on some platforms. + +Version 1.5.3beta05 [May 6, 2011] + Added the "_POSIX_SOURCE" feature test macro to ensure libpng sees the + correct API. _POSIX_SOURCE is defined in pngpriv.h, pngtest.c and + pngvalid.c to ensure that POSIX conformant systems disable non-POSIX APIs. + Removed png_snprintf and added formatted warning messages. This change adds + internal APIs to allow png_warning messages to have parameters without + requiring the host OS to implement snprintf. As a side effect the + dependency of the tIME-supporting RFC1132 code on stdio is removed and + PNG_NO_WARNINGS does actually work now. + Pass "" instead of '\0' to png_default_error() in png_err(). This mistake + was introduced in libpng-1.2.20beta01. This fixes CVE-2011-2691. + Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte + optimization configureable. + IDAT compression failed if preceded by a compressed text chunk (bug + introduced in libpng-1.5.3beta01-02). This was because the attempt to + reset the zlib stream in png_write_IDAT happened after the first IDAT + chunk had been deflated - much too late. In this change internal + functions were added to claim/release the z_stream and, hopefully, make + the code more robust. Also deflateEnd checking is added - previously + libpng would ignore an error at the end of the stream. + +Version 1.5.3beta06 [May 8, 2011] + Removed the -D_ALL_SOURCE from definitions for AIX in CMakeLists.txt + Implemented premultiplied alpha support: png_set_alpha_mode API + +Version 1.5.3beta07 [May 11, 2011] + Added expand_16 support to the high level interface. + Added named value and 'flag' gamma support to png_set_gamma. Made a minor + change from the previous (unreleased) ABI/API to hide the exact value used + for Macs - it's not a good idea to embed this in the ABI! + Moved macro definitions for PNG_HAVE_IHDR, PNG_HAVE_PLTE, and PNG_AFTER_IDAT + from pngpriv.h to png.h because they must be visible to applications + that call png_set_unknown_chunks(). + Check for up->location !PNG_AFTER_IDAT when writing unknown chunks + before IDAT. + +Version 1.5.3beta08 [May 16, 2011] + Improved "pngvalid --speed" to exclude more of pngvalid from the time. + Documented png_set_alpha_mode(), other changes in libpng.3/libpng-manual.txt + The cHRM chunk now sets the defaults for png_set_rgb_to_gray() (when negative + parameters are supplied by the caller), while in the absence of cHRM + sRGB/Rec 709 values are still used. This introduced a divide-by-zero + bug in png_handle_cHRM(). + The bKGD chunk no longer overwrites the background value set by + png_set_background(), allowing the latter to be used before the file + header is read. It never performed any useful function to override + the default anyway. + Added memory overwrite and palette image checks to pngvalid.c + Previously palette image code was poorly checked. Since the transformation + code has a special palette path in most cases this was a severe weakness. + Minor cleanup and some extra checking in pngrutil.c and pngrtran.c. When + expanding an indexed image, always expand to RGBA if transparency is + present. + +Version 1.5.3beta09 [May 17, 2011] + Reversed earlier 1.5.3 change of transformation order; move png_expand_16 + back where it was. The change doesn't work because it requires 16-bit + gamma tables when the code only generates 8-bit ones. This fails + silently; the libpng code just doesn't do any gamma correction. Moving + the tests back leaves the old, inaccurate, 8-bit gamma calculations, but + these are clearly better than none! + +Version 1.5.3beta10 [May 20, 2011] + + png_set_background() and png_expand_16() did not work together correctly. + This problem is present in 1.5.2; if png_set_background is called with + need_expand false and the matching 16 bit color libpng erroneously just + treats it as an 8-bit color because of where png_do_expand_16 is in the + transform list. This simple fix reduces the supplied colour to 8-bits, + so it gets smashed, but this is better than the current behavior. + Added tests for expand16, more fixes for palette image tests to pngvalid. + Corrects the code for palette image tests and disables attempts to + validate palette colors. + +Version 1.5.3rc01 [June 3, 2011] + No changes. + +Version 1.5.3rc02 [June 8, 2011] + Fixed uninitialized memory read in png_format_buffer() (Bug report by + Frank Busse, CVE-2011-2501, related to CVE-2004-0421). + +Version 1.5.3beta11 [June 11, 2011] + Fixed png_handle_sCAL which is broken in 1.5. This fixes CVE 2011-2692. + Added sCAL to pngtest.png + Revised documentation about png_set_user_limits() to say that it also affects + png writing. + Revised handling of png_set_user_limits() so that it can increase the + limit beyond the PNG_USER_WIDTH|HEIGHT_MAX; previously it could only + reduce it. + Make the 16-to-8 scaling accurate. Dividing by 256 with no rounding is + wrong (high by one) 25% of the time. Dividing by 257 with rounding is + wrong in 128 out of 65536 cases. Getting the right answer all the time + without division is easy. + Added "_SUPPORTED" to the PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION macro. + Added projects/owatcom, an IDE project for OpenWatcom to replace + scripts/makefile.watcom. This project works with OpenWatcom 1.9. The + IDE autogenerates appropriate makefiles (libpng.mk) for batch processing. + The project is configurable, unlike the Visual Studio project, so long + as the developer has an awk. + Changed png_set_gAMA to limit the gamma value range so that the inverse + of the stored value cannot overflow the fixed point representation, + and changed other things OpenWatcom warns about. + Revised pngvalid.c to test PNG_ALPHA_MODE_SUPPORTED correctly. This allows + pngvalid to build when ALPHA_MODE is not supported, which is required if + it is to build on libpng 1.4. + Removed string/memory macros that are no longer used and are not + necessarily fully supportable, particularly png_strncpy and png_snprintf. + Added log option to pngvalid.c and attempted to improve gamma messages. + +Version 1.5.3 [omitted] + People found the presence of a beta release following an rc release + to be confusing; therefore we bump the version to libpng-1.5.4beta01 + and there will be no libpng-1.5.3 release. + +Version 1.5.4beta01 [June 14, 2011] + Made it possible to undefine PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED + to get the same (inaccurate) output as libpng-1.5.2 and earlier. + Moved definitions of PNG_HAVE_IHDR, PNG_AFTER_IDAT, and PNG_HAVE_PLTE + outside of an unknown-chunk block in png.h because they are also + needed for other uses. + +Version 1.5.4beta02 [June 14, 2011] + Fixed and clarified LEGACY 16-to-8 scaling code. + Added png_set_chop_16() API, to match inaccurate results from previous + libpng versions. + Removed the ACCURATE and LEGACY options (they are no longer useable) + Use the old scaling method for background if png_set_chop_16() was + called. + Made png_set_chop_16() API removeable by disabling PNG_CHOP_16_TO_8_SUPPORTED + +Version 1.5.4beta03 [June 15, 2011] + Fixed a problem in png_do_expand_palette() exposed by optimization in + 1.5.3beta06 + Also removed a spurious and confusing "trans" member ("trans") from png_info. + The palette expand optimization prevented expansion to an intermediate RGBA + form if tRNS was present but alpha was marked to be stripped; this exposed + a check for tRNS in png_do_expand_palette() which is inconsistent with the + code elsewhere in libpng. + Correction to the expand_16 code; removed extra instance of + png_set_scale_16_to_8 from pngpriv.h + +Version 1.5.4beta04 [June 16, 2011] + Added a missing "#ifdef PNG_READ_BACKGROUND_SUPPORTED/#endif" in pngrtran.c + Added PNG_TRANSFORM_CHOP_16 to the high-level read transforms. + Made PNG_READ_16_TO_8_ACCURATE_SCALE configurable again. If this is + not enabled, png_set_strip_16() and png_do_scale_16_to_8() aren't built. + Revised contrib/visupng, gregbook, and pngminim to demonstrate chop_16_to_8 + +Version 1.5.4beta05 [June 16, 2011] + Renamed png_set_strip_16() to png_set_scale_16() and renamed + png_set_chop_16() to png_set_strip(16) in an attempt to minimize the + behavior changes between libpng14 and libpng15. + +Version 1.5.4beta06 [June 18, 2011] + Fixed new bug that was causing both strip_16 and scale_16 to be applied. + +Version 1.5.4beta07 [June 19, 2011] + Fixed pngvalid, simplified macros, added checking for 0 in sCAL. + The ACCURATE scale macro is no longer defined in 1.5 - call the + png_scale_16_to_8 API. Made sure that PNG_READ_16_TO_8 is still defined + if the png_strip_16_to_8 API is present. png_check_fp_number now + maintains some state so that positive, negative and zero values are + identified. sCAL uses these to be strictly spec conformant. + +Version 1.5.4beta08 [June 23, 2011] + Fixed pngvalid if ACCURATE_SCALE is defined. + Updated scripts/pnglibconf.h.prebuilt. + +Version 1.5.4rc01 [June 30, 2011] + Define PNG_ALLOCATED to "restrict" only if MSC_VER >= 1400. + +Version 1.5.4 [July 7, 2011] + No changes. + +Version 1.5.5beta01 [July 13, 2011] + Fixed some typos and made other minor changes in the manual. + Updated contrib/pngminus/makefile.std (Samuli Souminen) + +Version 1.5.5beta02 [July 14, 2011] + Revised Makefile.am and Makefile.in to look in the right directory for + pnglibconf.h.prebuilt + +Version 1.5.5beta03 [July 27, 2011] + Enabled compilation with g++ compiler. This compiler does not recognize + the file extension, so it always compiles with C++ rules. Made minor + changes to pngrutil.c to cast results where C++ expects it but C does not. + Minor editing of libpng.3 and libpng-manual.txt. + +Version 1.5.5beta04 [July 29, 2011] + Revised CMakeLists.txt (Clifford Yapp) + Updated commentary about the png_rgb_to_gray() default coefficients + in the manual and in pngrtran.c + +Version 1.5.5beta05 [August 17, 2011] + Prevent unexpected API exports from non-libpng DLLs on Windows. The "_DLL" + is removed from the test of whether a DLL is being built (this erroneously + caused the libpng APIs to be marked as DLL exports in static builds under + Microsoft Visual Studio). Almost all of the libpng building configuration + is moved from pngconf.h to pngpriv.h, but PNG_DLL_EXPORT remains in + pngconf.h, though, so that it is colocated with the import definition (it + is no longer used anywhere in the installed headers). The VStudio project + definitions have been cleaned up: "_USRDLL" has been removed from the + static library builds (this was incorrect), and PNG_USE_DLL has been added + to pngvalid to test the functionality (pngtest does not supply it, + deliberately). The spurious "_EXPORTS" has been removed from the + libpng build (all these errors were a result of copy/paste between project + configurations.) + Added new types and internal functions for CIE RGB end point handling to + pngpriv.h (functions yet to be implemented). + +Version 1.5.5beta06 [August 26, 2011] + Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set in CMakeLists.txt + (Clifford Yap) + Fixes to rgb_to_gray and cHRM XYZ APIs (John Bowler): + The rgb_to_gray code had errors when combined with gamma correction. + Some pixels were treated as true grey when they weren't and such pixels + and true grey ones were not gamma corrected (the original value of the + red component was used instead). APIs to get and set cHRM using color + space end points have been added and the rgb_to_gray code that defaults + based on cHRM, and the divide-by-zero bug in png_handle_cHRM (CERT + VU#477046, CVE-2011-3328, introduced in 1.5.4) have been corrected. + A considerable number of tests has been added to pngvalid for the + rgb_to_gray transform. + Arithmetic errors in rgb_to_gray whereby the calculated gray value was + truncated to the bit depth rather than rounded have been fixed except in + the 8-bit non-gamma-corrected case (where consistency seems more important + than correctness.) The code still has considerable inaccuracies in the + 8-bit case because 8-bit linear arithmetic is used. + +Version 1.5.5beta07 [September 7, 2011] + Added "$(ARCH)" option to makefile.darwin + Added SunOS support to configure.ac and Makefile.am + Changed png_chunk_benign_error() to png_warning() in png.c, in + png_XYZ_from_xy_checked(). + +Version 1.5.5beta08 [September 10, 2011] + Fixed 64-bit compilation errors (gcc). The errors fixed relate + to conditions where types that are 32 bits in the GCC 32-bit + world (uLong and png_size_t) become 64 bits in the 64-bit + world. This produces potential truncation errors which the + compiler correctly flags. + Relocated new HAVE_SOLARIS_LD definition in configure.ac + Constant changes for 64-bit compatibility (removal of L suffixes). The + 16-bit cases still use "L" as we don't have a 16-bit test system. + +Version 1.5.5rc01 [September 15, 2011] + Removed "L" suffixes in pngpriv.h + +Version 1.5.5 [September 22, 2011] + No changes. + +Version 1.5.6beta01 [September 22, 2011] + Fixed some 64-bit type conversion warnings in pngrtran.c + Moved row_info from png_struct to a local variable. + The various interlace mask arrays have been made into arrays of + bytes and made PNG_CONST and static (previously some arrays were + marked PNG_CONST and some weren't). + Additional checks have been added to the transform code to validate the + pixel depths after the transforms on both read and write. + Removed some redundant code from pngwrite.c, in png_destroy_write_struct(). + Changed chunk reading/writing code to use png_uint_32 instead of png_byte[4]. + This removes the need to allocate temporary strings for chunk names on + the stack in the read/write code. Unknown chunk handling still uses the + string form because this is exposed in the API. + +Version 1.5.6beta02 [September 26, 2011] + Added a note in the manual the png_read_update_info() must be called only + once with a particular info_ptr. + Fixed a typo in the definition of the new PNG_STRING_FROM_CHUNK(s,c) macro. + +Version 1.5.6beta03 [September 28, 2011] + Revised test-pngtest.sh to report FAIL when pngtest fails. + Added "--strict" option to pngtest, to report FAIL when the failure is + only because the resulting valid files are different. + Revised CMakeLists.txt to work with mingw and removed some material from + CMakeLists.txt that is no longer useful in libpng-1.5. + +Version 1.5.6beta04 [October 5, 2011] + Fixed typo in Makefile.in and Makefile.am ("-M Wl" should be "-M -Wl")." + +Version 1.5.6beta05 [October 12, 2011] + Speed up png_combine_row() for interlaced images. This reduces the generality + of the code, allowing it to be optimized for Adam7 interlace. The masks + passed to png_combine_row() are now generated internally, avoiding + some code duplication and localizing the interlace handling somewhat. + Align png_struct::row_buf - previously it was always unaligned, caused by + a bug in the code that attempted to align it; the code needs to subtract + one from the pointer to take account of the filter byte prepended to + each row. + Optimized png_combine_row() when rows are aligned. This gains a small + percentage for 16-bit and 32-bit pixels in the typical case where the + output row buffers are appropriately aligned. The optimization was not + previously possible because the png_struct buffer was always misaligned. + Fixed bug in png_write_chunk_header() debug print, introduced in 1.5.6beta01. + +Version 1.5.6beta06 [October 17, 2011] + Removed two redundant tests for unitialized row. + Fixed a relatively harmless memory overwrite in compressed text writing + with a 1 byte zlib buffer. + Add ability to call png_read_update_info multiple times to pngvalid.c. + Fixes for multiple calls to png_read_update_info. These fixes attend to + most of the errors revealed in pngvalid, however doing the gamma work + twice results in inaccuracies that can't be easily fixed. There is now + a warning in the code if this is going to happen. + Turned on multiple png_read_update_info in pngvalid transform tests. + Prevent libpng from overwriting unused bits at the end of the image when + it is not byte aligned, while reading. Prior to libpng-1.5.6 libpng would + overwrite the partial byte at the end of each row if the row width was not + an exact multiple of 8 bits and the image is not interlaced. + +Version 1.5.6beta07 [October 21, 2011] + Made png_ptr->prev_row an aligned pointer into png_ptr->big_prev_row + (Mans Rullgard). + +Version 1.5.6rc01 [October 26, 2011] + Changed misleading "Missing PLTE before cHRM" warning to "Out of place cHRM" + +Version 1.5.6rc02 [October 27, 2011] + Added LSR() macro to defend against buggy compilers that evaluate non-taken + code branches and complain about out-of-range shifts. + +Version 1.5.6rc03 [October 28, 2011] + Renamed the LSR() macro to PNG_LSR() and added PNG_LSL() macro. + Fixed compiler warnings with Intel and MSYS compilers. The logical shift + fix for Microsoft Visual C is required by other compilers, so this + enables that fix for all compilers when using compile-time constants. + Under MSYS 'byte' is a name declared in a system header file, so we + changed the name of a local variable to avoid the warnings that result. + Added #define PNG_ALIGN_TYPE PNG_ALIGN_NONE to contrib/pngminim/*/pngusr.h + +Version 1.5.6 [November 3, 2011] + No changes. + +Version 1.5.7beta01 [November 4, 2011] + Added support for ARM processor (Mans Rullgard) + Fixed bug in pngvalid on early allocation failure; fixed type cast in + pngmem.c; pngvalid would attempt to call png_error() if the allocation + of a png_struct or png_info failed. This would probably have led to a + crash. The pngmem.c implementation of png_malloc() included a cast + to png_size_t which would fail on large allocations on 16-bit systems. + Fix for the preprocessor of the Intel C compiler. The preprocessor + splits adjacent @ signs with a space; this changes the concatentation + token from @-@-@ to PNG_JOIN; that should work with all compiler + preprocessors. + Paeth filter speed improvements from work by Siarhei Siamashka. This + changes the 'Paeth' reconstruction function to improve the GCC code + generation on x86. The changes are only part of the suggested ones; + just the changes that definitely improve speed and remain simple. + The changes also slightly increase the clarity of the code. + +Version 1.5.7beta02 [November 11, 2011] + Check compression_type parameter in png_get_iCCP and remove spurious + casts. The compression_type parameter is always assigned to, so must + be non-NULL. The cast of the profile length potentially truncated the + value unnecessarily on a 16-bit int system, so the cast of the (byte) + compression type to (int) is specified by ANSI-C anyway. + Fixed FP division by zero in pngvalid.c; the 'test_pixel' code left + the sBIT fields in the test pixel as 0, which resulted in a floating + point division by zero which was irrelevant but causes systems where + FP exceptions cause a crash. Added code to pngvalid to turn on FP + exceptions if the appropriate glibc support is there to ensure this is + tested in the future. + Updated scripts/pnglibconf.mak and scripts/makefile.std to handle the + new PNG_JOIN macro. + Added versioning to pnglibconf.h comments. + Simplified read/write API initial version; basic read/write tested on + a variety of images, limited documentation (in the header file.) + Installed more accurate linear to sRGB conversion tables. The slightly + modified tables reduce the number of 16-bit values that + convert to an off-by-one 8-bit value. The "makesRGB.c" code that was used + to generate the tables is now in a contrib/sRGBtables sub-directory. + +Version 1.5.7beta03 [November 17, 2011] + Removed PNG_CONST from the sRGB table declarations in pngpriv.h and png.c + Added run-time detection of NEON support. + Added contrib/libtests; includes simplified API test and timing test and + a color conversion utility for rapid checking of failed 'pngstest' results. + Multiple transform bug fixes plus a work-round for double gamma correction. + libpng does not support more than one transform that requires linear data + at once - if this is tried typically the results is double gamma + correction. Since the simplified APIs can need rgb to gray combined with + a compose operation it is necessary to do one of these outside the main + libpng transform code. This check-in also contains fixes to various bugs + in the simplified APIs themselves and to some bugs in compose and rgb to + gray (on palette) itself. + Fixes for C++ compilation using g++ When libpng source is compiled + using g++. The compiler imposes C++ rules on the C source; thus it + is desireable to make the source work with either C or C++ rules + without throwing away useful error information. This change adds + png_voidcast to allow C semantic (void*) cases or the corresponding + C++ static_cast operation, as appropriate. + Added --noexecstack to assembler file compilation. GCC does not set + this on assembler compilation, even though it does on C compilation. + This creates security issues if assembler code is enabled; the + work-around is to set it by default in the flags for $(CCAS) + Work around compilers that don't support declaration of const data. Some + compilers fault 'extern const' data declarations (because the data is + not initialized); this turns on const-ness only for compilers where + this is known to work. + +Version 1.5.7beta04 [November 17, 2011] + Since the gcc driver does not recognize the --noexecstack flag, we must + use the -Wa prefix to have it passed through to the assembler. + Also removed a duplicate setting of this flag. + Added files that were omitted from the libpng-1.5.7beta03 zip distribution. + +Version 1.5.7beta05 [November 25, 2011] + Removed "zTXt" from warning in generic chunk decompression function. + Validate time settings passed to pngset() and png_convert_to_rfc1123() + (Frank Busse). + Added MINGW support to CMakeLists.txt + Reject invalid compression flag or method when reading the iTXt chunk. + Backed out 'simplified' API changes. The API seems too complex and there + is a lack of consensus or enthusiasm for the proposals. The API also + reveals significant bugs inside libpng (double gamma correction and the + known bug of being unable to retrieve a corrected palette). It seems + better to wait until the bugs, at least, are corrected. + Moved pngvalid.c into contrib/libtests + Rebuilt Makefile.in, configure, etc., with autoconf-2.68 + +Version 1.5.7rc01 [December 1, 2011] + Replaced an "#if" with "#ifdef" in pngrtran.c + Revised #if PNG_DO_BC block in png.c (use #ifdef and add #else) + +Version 1.5.7rc02 [December 5, 2011] + Revised project files and contrib/pngvalid/pngvalid.c to account for + the relocation of pngvalid into contrib/libtests. + Revised pngconf.h to use " __declspec(restrict)" only when MSC_VER >= 1400, + as in libpng-1.5.4. + Put CRLF line endings in the owatcom project files. + +Version 1.5.7rc03 [December 7, 2011] + Updated CMakeLists.txt to account for the relocation of pngvalid.c + +Version 1.5.7 [December 15, 2011] + Minor fixes to pngvalid.c for gcc 4.6.2 compatibility to remove warnings + reported by earlier versions. + +Version 1.5.8beta01 [January 15, 2011] + Removed '#include config.h"' from contrib/libtests/pngvalid.c. It's not + needed and causes trouble for VPATH building. + Moved AC_MSG_CHECKING([if libraries can be versioned]) later to the proper + location in configure.ac (Gilles Espinasse). + Fix bug in pngerror.c: some long warnings were being improperly truncated + (CVE-2011-3464, bug introduced in libpng-1.5.3beta05). + +Version 1.5.8rc01 [January 21, 2012] + No changes. + +Version 1.5.8rc02 [January 25, 2012] + Fixed Min/GW uninstall to remove libpng.dll.a + Conditionalize the install rules for MINGW and CYGWIN in CMakeLists.txt + +Version 1.5.8 [February 1, 2012] + No changes. + +Version 1.5.9beta01 [February 3, 2012] + Rebuilt configure scripts in the tar distributions. + +Version 1.5.9beta02 [February 16, 2012] + Removed two unused definitions from scripts/pnglibconf.h.prebuilt + Removed some unused arrays (with #ifdef) from png_read_push_finish_row(). + Removed tests for no-longer-used *_EMPTY_PLTE_SUPPORTED from pngstruct.h + +Version 1.5.9rc01 [February 17, 2012] + Fixed CVE-2011-3026 buffer overrun bug. This bug was introduced when + iCCP chunk support was added at libpng-1.0.6. Deal more correctly with the + test on iCCP chunk length. Also removed spurious casts that may hide + problems on 16-bit systems. + +Version 1.5.9 [February 18, 2012] + No changes. + +Version 1.5.10beta01 [February 24, 2012] + Removed two useless #ifdef directives from pngread.c and one from pngrutil.c + Always put the CMAKE_LIBRARY in "lib" (removed special WIN32 case). + Removed empty vstudio/pngstest directory (Clifford Yapp). + Eliminated redundant png_push_read_tEXt|zTXt|iTXt|unknown code from + pngpread.c and use the sequential png_handle_tEXt, etc., in pngrutil.c; + now that png_ptr->buffer is inaccessible to applications, the special + handling is no longer useful. + Fixed bug with png_handle_hIST with odd chunk length (Frank Busse). + Added PNG_SAFE_LIMITS feature to pnglibconf.dfa and code in pngconf.h + to reset the user limits to safe ones if PNG_SAFE_LIMITS is defined. + To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED" on the configure + command or put "#define PNG_SAFE_LIMITS_SUPPORTED" in pnglibconf.h. + Revised the SAFE_LIMITS feature to be the same as the feature in libpng16. + Added information about the new limits in the manual. + +Version 1.5.10beta02 [February 27, 2012] + Updated Makefile.in + +Version 1.5.10beta03 [March 6, 2012] + Removed unused "current_text" members of png_struct and the png_free() + of png_ptr->current_text from pngread.c + Added palette-index checking. Issue a png_warning() if an invalid index is + found. + +Version 1.5.10beta04 [March 10, 2012] + Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition. + Fixed CMF optimization of non-IDAT compressed chunks, which was added at + libpng-1.5.4. It sometimes produced too small of a window. + +Version 1.5.10beta05 [March 10, 2012] + Reject all iCCP chunks after the first, even if the first one is invalid. + Issue a png_benign_error() instead of png_warning() about bad palette index. + Fixed an off-by-one error in the palette index checking function. + Revised example.c to put text strings in a temporary character array + instead of directly assigning string constants to png_textp members. + This avoids compiler warnings when -Wwrite-strings is enabled. + +Version 1.5.10 [March 29, 2012] + Prevent PNG_EXPAND+PNG_SHIFT doing the shift twice. + Revised png_set_text_2() to avoid potential memory corruption (fixes + CVE-2011-3048). + +Version 1.5.11beta01 [April 28, 2012] + Revised scripts/makefile.darwin: use system zlib; remove quotes around + architecture list; add missing ppc architecture; add architecture options + to shared library link; don't try to create a shared lib based on missing + RELEASE variable. + Enable png_set_check_for_invalid_index() for both read and write. + Removed #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED/#endif in pngpriv.h around + declaration of png_handle_unknown(). + Added -lssp_nonshared in a comment in scripts/makefile.freebsd + and changed deprecated NOOBJ and NOPROFILE to NO_OBJ and NO_PROFILE. + +Version 1.5.11rc01 [May 23, 2012] + No changes. + +Version 1.5.11rc02 [May 29, 2012] + Fixed some typos in comments. + Revised CMakeLists.txt to not attempt to make a symlink under mingw. + Added two images to contrib/pngsuite (1-bit and 2-bit transparent grayscale), + and renamed three whose names were inconsistent with those in + pngsuite/README.txt. + +Version 1.5.11rc03 [June 4, 2012] + Do not depend upon a GCC feature macro being available for use in generating + the linker mapfile symbol prefix. + Made fixes for new optimization warnings from gcc 4.7.0. The compiler + performed an optimization which is safe but then warned about it. + Changing the type of 'palette_number' in pngvalid.c removes the warning. + +Version 1.5.11rc04 [June 6, 2012] + Improved performance of new do_check_palette_indexes() function. + +Version 1.5.11rc05 [June 7, 2012] + Don't check palette indexes if num_palette is 0 (as it can be in MNG files). + +Version 1.5.11 [June 14, 2012] + Include zlib.h in contrib/gregbook and contrib/visupng examples. + +Version 1.5.12 [July 11, 2012] + Removed scripts/makefile.cegcc from the *.zip and *.7z distributions; it + depends on configure, which is not included in those archives. + Changed "a+w" to "u+w" in Makefile.in to fix CVE-2012-3386. + Send comments/corrections/commendations to png-mng-implement at lists.sf.net (subscription required; visit https://lists.sourceforge.net/lists/listinfo/png-mng-implement @@ -3293,5 +3903,4 @@ or to glennrp at users.sourceforge.net Glenn R-P -*/ } #endif Index: dll/3rdparty/libpng/docs/example.c =================================================================== --- dll/3rdparty/libpng/docs/example.c (revision 56925) +++ dll/3rdparty/libpng/docs/example.c (working copy) @@ -2,11 +2,10 @@ #if 0 /* in case someone actually tries to compile this */ /* example.c - an example of using libpng - * Last changed in libpng 1.5.2 [March 31, 2011] - * This file has been placed in the public domain by the authors. - * Maintained 1998-2011 Glenn Randers-Pehrson - * Maintained 1996, 1997 Andreas Dilger) - * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) + * Last changed in libpng 1.5.10 [March 8, 2012] + * Maintained 1998-2012 Glenn Randers-Pehrson + * Maintained 1996, 1997 Andreas Dilger + * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc. */ /* This is an example of how to use libpng to read and write PNG files. @@ -14,6 +13,8 @@ * read it, do so first. This was designed to be a starting point of an * implementation. This is not officially part of libpng, is hereby placed * in the public domain, and therefore does not require a copyright notice. + * To the extent possible under law, the authors have waived all copyright and + * related or neighboring rights to this file. * * This file does not currently compile, because it is missing certain * parts, like allocating memory to hold an image. You will have to @@ -22,6 +23,10 @@ * see also the programs in the contrib directory. */ +#define _POSIX_SOURCE 1 /* libpng and zlib are POSIX-compliant. You may + * change this if your application uses non-POSIX + * extensions. */ + #include "png.h" /* The png_jmpbuf() macro, used in error handling, became available in @@ -183,8 +188,15 @@ * are mutually exclusive. */ - /* Tell libpng to strip 16 bit/color files down to 8 bits/color */ + /* Tell libpng to strip 16 bit/color files down to 8 bits/color. + * Use accurate scaling if it's available, otherwise just chop off the + * low byte. + */ +#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED + png_set_scale_16(png_ptr); +#else png_set_strip_16(png_ptr); +#endif /* Strip alpha bytes from the input data without combining with the * background (not recommended). @@ -330,12 +342,17 @@ /* Add filler (or alpha) byte (before/after each RGB triplet) */ png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); +#ifdef PNG_READ_INTERLACING_SUPPORTED /* Turn on interlace handling. REQUIRED if you are not using * png_read_image(). To see how to handle interlacing passes, * see the png_read_row() method below: */ number_passes = png_set_interlace_handling(png_ptr); +#else + number_passes = 1; +#endif /* PNG_READ_INTERLACING_SUPPORTED */ + /* Optional call to gamma correct and add the background to the palette * and update info structure. REQUIRED if you are expecting libpng to * update the palette for you (ie you selected such a transform above). @@ -516,6 +533,7 @@ */ png_bytep old_row = ((png_bytep *)our_data)[row_num]; +#ifdef PNG_READ_INTERLACING_SUPPORTED /* If both rows are allocated then copy the new row * data to the corresponding row data. */ @@ -544,6 +562,7 @@ * to pass the current row as new_row, and the function will combine * the old row and the new row. */ +#endif /* PNG_READ_INTERLACING_SUPPORTED */ } end_callback(png_structp png_ptr, png_infop info) @@ -676,26 +695,39 @@ png_set_gAMA(png_ptr, info_ptr, gamma); /* Optionally write comments into the image */ - text_ptr[0].key = "Title"; - text_ptr[0].text = "Mona Lisa"; - text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; - text_ptr[0].itxt_length = 0; - text_ptr[0].lang = NULL; - text_ptr[0].lang_key = NULL; - text_ptr[1].key = "Author"; - text_ptr[1].text = "Leonardo DaVinci"; - text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; - text_ptr[1].itxt_length = 0; - text_ptr[1].lang = NULL; - text_ptr[1].lang_key = NULL; - text_ptr[2].key = "Description"; - text_ptr[2].text = ""; - text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; - text_ptr[2].itxt_length = 0; - text_ptr[2].lang = NULL; - text_ptr[2].lang_key = NULL; - png_set_text(png_ptr, info_ptr, text_ptr, 3); + { + png_text text_ptr[3]; + char key0[]="Title"; + char text0[]="Mona Lisa"; + text_ptr[0].key = key0; + text_ptr[0].text = text0; + text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; + text_ptr[0].itxt_length = 0; + text_ptr[0].lang = NULL; + text_ptr[0].lang_key = NULL; + + char key1[]="Author"; + char text1[]="Leonardo DaVinci"; + text_ptr[1].key = key1; + text_ptr[1].text = text1; + text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; + text_ptr[1].itxt_length = 0; + text_ptr[1].lang = NULL; + text_ptr[1].lang_key = NULL; + + char key2[]="Description"; + char text2[]=""; + text_ptr[2].key = key2; + text_ptr[2].text = text2; + text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; + text_ptr[2].itxt_length = 0; + text_ptr[2].lang = NULL; + text_ptr[2].lang_key = NULL; + + png_set_text(write_ptr, write_info_ptr, text_ptr, 3); + } + /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */ /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored Index: dll/3rdparty/libpng/docs/INSTALL =================================================================== --- dll/3rdparty/libpng/docs/INSTALL (revision 56925) +++ dll/3rdparty/libpng/docs/INSTALL (working copy) @@ -133,3 +133,23 @@ Further information can be found in the README and libpng-manual.txt files, in the individual makefiles, in png.h, and the manual pages libpng.3 and png.5. + +Using the ./configure script -- 16 December 2002. +================================================= + +The ./configure script should work compatibly with what scripts/makefile.* +did, however there are some options you might need to add to configure +explicitly, which previously was done semi-automatically (if you didn't edit +scripts/makefile.* yourself, that is) + +CFLAGS="-Wall -O -funroll-loops \ +-malign-loops=2 -malign-functions=2" ./configure --prefix=/usr/include \ +--with-pkgconfigdir=/usr/lib/pkgconfig --includedir=/usr/include + +You can alternatively specify --includedir=/usr/include, /usr/local/include, +/usr/include/libpng%NN%, or whatever. + +If you find that the configure script is out-of-date or is not supporting +your platform properly, try running autogen.sh to regenerate "configure", +"Makefile.in", and the other configuration files. Then try configure again. + Index: dll/3rdparty/libpng/docs/libpng-1.4.3.txt =================================================================== --- dll/3rdparty/libpng/docs/libpng-1.4.3.txt (revision 56925) +++ dll/3rdparty/libpng/docs/libpng-1.4.3.txt (working copy) @@ -1,3352 +0,0 @@ -libpng.txt - A description on how to use and modify libpng - - libpng version 1.4.3 - June 26, 2010 - Updated and distributed by Glenn Randers-Pehrson - - Copyright (c) 1998-2009 Glenn Randers-Pehrson - - This document is released under the libpng license. - For conditions of distribution and use, see the disclaimer - and license in png.h - - Based on: - - libpng versions 0.97, January 1998, through 1.4.3 - June 26, 2010 - Updated and distributed by Glenn Randers-Pehrson - Copyright (c) 1998-2009 Glenn Randers-Pehrson - - libpng 1.0 beta 6 version 0.96 May 28, 1997 - Updated and distributed by Andreas Dilger - Copyright (c) 1996, 1997 Andreas Dilger - - libpng 1.0 beta 2 - version 0.88 January 26, 1996 - For conditions of distribution and use, see copyright - notice in png.h. Copyright (c) 1995, 1996 Guy Eric - Schalnat, Group 42, Inc. - - Updated/rewritten per request in the libpng FAQ - Copyright (c) 1995, 1996 Frank J. T. Wojcik - December 18, 1995 & January 20, 1996 - -I. Introduction - -This file describes how to use and modify the PNG reference library -(known as libpng) for your own use. There are five sections to this -file: introduction, structures, reading, writing, and modification and -configuration notes for various special platforms. In addition to this -file, example.c is a good starting point for using the library, as -it is heavily commented and should include everything most people -will need. We assume that libpng is already installed; see the -INSTALL file for instructions on how to install libpng. - -For examples of libpng usage, see the files "example.c", "pngtest.c", -and the files in the "contrib" directory, all of which are included in -the libpng distribution. - -Libpng was written as a companion to the PNG specification, as a way -of reducing the amount of time and effort it takes to support the PNG -file format in application programs. - -The PNG specification (second edition), November 2003, is available as -a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at -. It is technically equivalent -to the PNG specification (second edition) but has some additional material. - -The PNG-1.0 specification is available -as RFC 2083 and as a -W3C Recommendation . - -Some additional chunks are described in the special-purpose public chunks -documents at . - -Other information -about PNG, and the latest version of libpng, can be found at the PNG home -page, . - -Most users will not have to modify the library significantly; advanced -users may want to modify it more. All attempts were made to make it as -complete as possible, while keeping the code easy to understand. -Currently, this library only supports C. Support for other languages -is being considered. - -Libpng has been designed to handle multiple sessions at one time, -to be easily modifiable, to be portable to the vast majority of -machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy -to use. The ultimate goal of libpng is to promote the acceptance of -the PNG file format in whatever way possible. While there is still -work to be done (see the TODO file), libpng should cover the -majority of the needs of its users. - -Libpng uses zlib for its compression and decompression of PNG files. -Further information about zlib, and the latest version of zlib, can -be found at the zlib home page, . -The zlib compression utility is a general purpose utility that is -useful for more than PNG files, and can be used without libpng. -See the documentation delivered with zlib for more details. -You can usually find the source files for the zlib utility wherever you -find the libpng source files. - -Libpng is thread safe, provided the threads are using different -instances of the structures. Each thread should have its own -png_struct and png_info instances, and thus its own image. -Libpng does not protect itself against two threads using the -same instance of a structure. - -II. Structures - -There are two main structures that are important to libpng, png_struct -and png_info. The first, png_struct, is an internal structure that -will not, for the most part, be used by a user except as the first -variable passed to every libpng function call. - -The png_info structure is designed to provide information about the -PNG file. At one time, the fields of png_info were intended to be -directly accessible to the user. However, this tended to cause problems -with applications using dynamically loaded libraries, and as a result -a set of interface functions for png_info (the png_get_*() and png_set_*() -functions) was developed. The fields of png_info are still available for -older applications, but it is suggested that applications use the new -interfaces if at all possible. - -Applications that do make direct access to the members of png_struct (except -for png_ptr->jmpbuf) must be recompiled whenever the library is updated, -and applications that make direct access to the members of png_info must -be recompiled if they were compiled or loaded with libpng version 1.0.6, -in which the members were in a different order. In version 1.0.7, the -members of the png_info structure reverted to the old order, as they were -in versions 0.97c through 1.0.5. Starting with version 2.0.0, both -structures are going to be hidden, and the contents of the structures will -only be accessible through the png_get/png_set functions. - -The png.h header file is an invaluable reference for programming with libpng. -And while I'm on the topic, make sure you include the libpng header file: - -#include - -III. Reading - -We'll now walk you through the possible functions to call when reading -in a PNG file sequentially, briefly explaining the syntax and purpose -of each one. See example.c and png.h for more detail. While -progressive reading is covered in the next section, you will still -need some of the functions discussed in this section to read a PNG -file. - -Setup - -You will want to do the I/O initialization(*) before you get into libpng, -so if it doesn't work, you don't have much to undo. Of course, you -will also want to insure that you are, in fact, dealing with a PNG -file. Libpng provides a simple check to see if a file is a PNG file. -To use it, pass in the first 1 to 8 bytes of the file to the function -png_sig_cmp(), and it will return 0 (false) if the bytes match the -corresponding bytes of the PNG signature, or nonzero (true) otherwise. -Of course, the more bytes you pass in, the greater the accuracy of the -prediction. - -If you are intending to keep the file pointer open for use in libpng, -you must ensure you don't read more than 8 bytes from the beginning -of the file, and you also have to make a call to png_set_sig_bytes_read() -with the number of bytes you read from the beginning. Libpng will -then only check the bytes (if any) that your program didn't read. - -(*): If you are not using the standard I/O functions, you will need -to replace them with custom functions. See the discussion under -Customizing libpng. - - - FILE *fp = fopen(file_name, "rb"); - if (!fp) - { - return (ERROR); - } - fread(header, 1, number, fp); - is_png = !png_sig_cmp(header, 0, number); - if (!is_png) - { - return (NOT_PNG); - } - - -Next, png_struct and png_info need to be allocated and initialized. In -order to ensure that the size of these structures is correct even with a -dynamically linked libpng, there are functions to initialize and -allocate the structures. We also pass the library version, optional -pointers to error handling functions, and a pointer to a data struct for -use by the error functions, if necessary (the pointer and functions can -be NULL if the default error handlers are to be used). See the section -on Changes to Libpng below regarding the old initialization functions. -The structure allocation functions quietly return NULL if they fail to -create the structure, so your application should check for that. - - png_structp png_ptr = png_create_read_struct - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, - user_error_fn, user_warning_fn); - if (!png_ptr) - return (ERROR); - - png_infop info_ptr = png_create_info_struct(png_ptr); - if (!info_ptr) - { - png_destroy_read_struct(&png_ptr, - (png_infopp)NULL, (png_infopp)NULL); - return (ERROR); - } - - png_infop end_info = png_create_info_struct(png_ptr); - if (!end_info) - { - png_destroy_read_struct(&png_ptr, &info_ptr, - (png_infopp)NULL); - return (ERROR); - } - -If you want to use your own memory allocation routines, -define PNG_USER_MEM_SUPPORTED and use -png_create_read_struct_2() instead of png_create_read_struct(): - - png_structp png_ptr = png_create_read_struct_2 - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, - user_error_fn, user_warning_fn, (png_voidp) - user_mem_ptr, user_malloc_fn, user_free_fn); - -The error handling routines passed to png_create_read_struct() -and the memory alloc/free routines passed to png_create_struct_2() -are only necessary if you are not using the libpng supplied error -handling and memory alloc/free functions. - -When libpng encounters an error, it expects to longjmp back -to your routine. Therefore, you will need to call setjmp and pass -your png_jmpbuf(png_ptr). If you read the file from different -routines, you will need to update the jmpbuf field every time you enter -a new routine that will call a png_*() function. - -See your documentation of setjmp/longjmp for your compiler for more -information on setjmp/longjmp. See the discussion on libpng error -handling in the Customizing Libpng section below for more information -on the libpng error handling. If an error occurs, and libpng longjmp's -back to your setjmp, you will want to call png_destroy_read_struct() to -free any memory. - - if (setjmp(png_jmpbuf(png_ptr))) - { - png_destroy_read_struct(&png_ptr, &info_ptr, - &end_info); - fclose(fp); - return (ERROR); - } - -If you would rather avoid the complexity of setjmp/longjmp issues, -you can compile libpng with PNG_NO_SETJMP, in which case -errors will result in a call to PNG_ABORT() which defaults to abort(). - -You can #define PNG_ABORT() to a function that does something -more useful than abort(), as long as your function does not -return. - -Now you need to set up the input code. The default for libpng is to -use the C function fread(). If you use this, you will need to pass a -valid FILE * in the function png_init_io(). Be sure that the file is -opened in binary mode. If you wish to handle reading data in another -way, you need not call the png_init_io() function, but you must then -implement the libpng I/O methods discussed in the Customizing Libpng -section below. - - png_init_io(png_ptr, fp); - -If you had previously opened the file and read any of the signature from -the beginning in order to see if this was a PNG file, you need to let -libpng know that there are some bytes missing from the start of the file. - - png_set_sig_bytes(png_ptr, number); - -You can change the zlib compression buffer size to be used while -reading compressed data with - - png_set_compression_buffer_size(png_ptr, buffer_size); - -where the default size is 8192 bytes. Note that the buffer size -is changed immediately and the buffer is reallocated immediately, -instead of setting a flag to be acted upon later. - -Setting up callback code - -You can set up a callback function to handle any unknown chunks in the -input stream. You must supply the function - - read_chunk_callback(png_ptr ptr, - png_unknown_chunkp chunk); - { - /* The unknown chunk structure contains your - chunk data, along with similar data for any other - unknown chunks: */ - - png_byte name[5]; - png_byte *data; - png_size_t size; - - /* Note that libpng has already taken care of - the CRC handling */ - - /* put your code here. Search for your chunk in the - unknown chunk structure, process it, and return one - of the following: */ - - return (-n); /* chunk had an error */ - return (0); /* did not recognize */ - return (n); /* success */ - } - -(You can give your function another name that you like instead of -"read_chunk_callback") - -To inform libpng about your function, use - - png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr, - read_chunk_callback); - -This names not only the callback function, but also a user pointer that -you can retrieve with - - png_get_user_chunk_ptr(png_ptr); - -If you call the png_set_read_user_chunk_fn() function, then all unknown -chunks will be saved when read, in case your callback function will need -one or more of them. This behavior can be changed with the -png_set_keep_unknown_chunks() function, described below. - -At this point, you can set up a callback function that will be -called after each row has been read, which you can use to control -a progress meter or the like. It's demonstrated in pngtest.c. -You must supply a function - - void read_row_callback(png_ptr ptr, png_uint_32 row, - int pass); - { - /* put your code here */ - } - -(You can give it another name that you like instead of "read_row_callback") - -To inform libpng about your function, use - - png_set_read_status_fn(png_ptr, read_row_callback); - -Unknown-chunk handling - -Now you get to set the way the library processes unknown chunks in the -input PNG stream. Both known and unknown chunks will be read. Normal -behavior is that known chunks will be parsed into information in -various info_ptr members while unknown chunks will be discarded. This -behavior can be wasteful if your application will never use some known -chunk types. To change this, you can call: - - png_set_keep_unknown_chunks(png_ptr, keep, - chunk_list, num_chunks); - keep - 0: default unknown chunk handling - 1: ignore; do not keep - 2: keep only if safe-to-copy - 3: keep even if unsafe-to-copy - You can use these definitions: - PNG_HANDLE_CHUNK_AS_DEFAULT 0 - PNG_HANDLE_CHUNK_NEVER 1 - PNG_HANDLE_CHUNK_IF_SAFE 2 - PNG_HANDLE_CHUNK_ALWAYS 3 - chunk_list - list of chunks affected (a byte string, - five bytes per chunk, NULL or '\0' if - num_chunks is 0) - num_chunks - number of chunks affected; if 0, all - unknown chunks are affected. If nonzero, - only the chunks in the list are affected - -Unknown chunks declared in this way will be saved as raw data onto a -list of png_unknown_chunk structures. If a chunk that is normally -known to libpng is named in the list, it will be handled as unknown, -according to the "keep" directive. If a chunk is named in successive -instances of png_set_keep_unknown_chunks(), the final instance will -take precedence. The IHDR and IEND chunks should not be named in -chunk_list; if they are, libpng will process them normally anyway. - -Here is an example of the usage of png_set_keep_unknown_chunks(), -where the private "vpAg" chunk will later be processed by a user chunk -callback function: - - png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'}; - - #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) - png_byte unused_chunks[]= - { - 104, 73, 83, 84, (png_byte) '\0', /* hIST */ - 105, 84, 88, 116, (png_byte) '\0', /* iTXt */ - 112, 67, 65, 76, (png_byte) '\0', /* pCAL */ - 115, 67, 65, 76, (png_byte) '\0', /* sCAL */ - 115, 80, 76, 84, (png_byte) '\0', /* sPLT */ - 116, 73, 77, 69, (png_byte) '\0', /* tIME */ - }; - #endif - - ... - - #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) - /* ignore all unknown chunks: */ - png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0); - /* except for vpAg: */ - png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1); - /* also ignore unused known chunks: */ - png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks, - (int)sizeof(unused_chunks)/5); - #endif - -User limits - -The PNG specification allows the width and height of an image to be as -large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns. -Since very few applications really need to process such large images, -we have imposed an arbitrary 1-million limit on rows and columns. -Larger images will be rejected immediately with a png_error() call. If -you wish to override this limit, you can use - - png_set_user_limits(png_ptr, width_max, height_max); - -to set your own limits, or use width_max = height_max = 0x7fffffffL -to allow all valid dimensions (libpng may reject some very large images -anyway because of potential buffer overflow conditions). - -You should put this statement after you create the PNG structure and -before calling png_read_info(), png_read_png(), or png_process_data(). -If you need to retrieve the limits that are being applied, use - - width_max = png_get_user_width_max(png_ptr); - height_max = png_get_user_height_max(png_ptr); - -The PNG specification sets no limit on the number of ancillary chunks -allowed in a PNG datastream. You can impose a limit on the total number -of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with - - png_set_chunk_cache_max(png_ptr, user_chunk_cache_max); - -where 0x7fffffffL means unlimited. You can retrieve this limit with - - chunk_cache_max = png_get_chunk_cache_max(png_ptr); - -This limit also applies to the number of buffers that can be allocated -by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks. - -You can also set a limit on the amount of memory that a compressed chunk -other than IDAT can occupy, with - - png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max); - -and you can retrieve the limit with - - chunk_malloc_max = png_get_chunk_malloc_max(png_ptr); - -Any chunks that would cause either of these limits to be exceeded will -be ignored. - -The high-level read interface - -At this point there are two ways to proceed; through the high-level -read interface, or through a sequence of low-level read operations. -You can use the high-level interface if (a) you are willing to read -the entire image into memory, and (b) the input transformations -you want to do are limited to the following set: - - PNG_TRANSFORM_IDENTITY No transformation - PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to - 8 bits - PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel - PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit - samples to bytes - PNG_TRANSFORM_PACKSWAP Change order of packed - pixels to LSB first - PNG_TRANSFORM_EXPAND Perform set_expand() - PNG_TRANSFORM_INVERT_MONO Invert monochrome images - PNG_TRANSFORM_SHIFT Normalize pixels to the - sBIT depth - PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA - to BGRA - PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA - to AG - PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity - to transparency - PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples - PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples - to RGB (or GA to RGBA) - -(This excludes setting a background color, doing gamma transformation, -quantizing, and setting filler.) If this is the case, simply do this: - - png_read_png(png_ptr, info_ptr, png_transforms, NULL) - -where png_transforms is an integer containing the bitwise OR of some -set of transformation flags. This call is equivalent to png_read_info(), -followed the set of transformations indicated by the transform mask, -then png_read_image(), and finally png_read_end(). - -(The final parameter of this call is not yet used. Someday it might point -to transformation parameters required by some future input transform.) - -You must use png_transforms and not call any png_set_transform() functions -when you use png_read_png(). - -After you have called png_read_png(), you can retrieve the image data -with - - row_pointers = png_get_rows(png_ptr, info_ptr); - -where row_pointers is an array of pointers to the pixel data for each row: - - png_bytep row_pointers[height]; - -If you know your image size and pixel size ahead of time, you can allocate -row_pointers prior to calling png_read_png() with - - if (height > PNG_UINT_32_MAX/png_sizeof(png_byte)) - png_error (png_ptr, - "Image is too tall to process in memory"); - if (width > PNG_UINT_32_MAX/pixel_size) - png_error (png_ptr, - "Image is too wide to process in memory"); - row_pointers = png_malloc(png_ptr, - height*png_sizeof(png_bytep)); - for (int i=0; i) and -png_get_(png_ptr, info_ptr, ...) functions return non-zero if the -data has been read, or zero if it is missing. The parameters to the -png_get_ are set directly if they are simple data types, or a -pointer into the info_ptr is returned for any complex types. - - png_get_PLTE(png_ptr, info_ptr, &palette, - &num_palette); - palette - the palette for the file - (array of png_color) - num_palette - number of entries in the palette - - png_get_gAMA(png_ptr, info_ptr, &gamma); - gamma - the gamma the file is written - at (PNG_INFO_gAMA) - - png_get_sRGB(png_ptr, info_ptr, &srgb_intent); - srgb_intent - the rendering intent (PNG_INFO_sRGB) - The presence of the sRGB chunk - means that the pixel data is in the - sRGB color space. This chunk also - implies specific values of gAMA and - cHRM. - - png_get_iCCP(png_ptr, info_ptr, &name, - &compression_type, &profile, &proflen); - name - The profile name. - compression - The compression type; always - PNG_COMPRESSION_TYPE_BASE for PNG 1.0. - You may give NULL to this argument to - ignore it. - profile - International Color Consortium color - profile data. May contain NULs. - proflen - length of profile data in bytes. - - png_get_sBIT(png_ptr, info_ptr, &sig_bit); - sig_bit - the number of significant bits for - (PNG_INFO_sBIT) each of the gray, - red, green, and blue channels, - whichever are appropriate for the - given color type (png_color_16) - - png_get_tRNS(png_ptr, info_ptr, &trans_alpha, - &num_trans, &trans_color); - trans_alpha - array of alpha (transparency) - entries for palette (PNG_INFO_tRNS) - trans_color - graylevel or color sample values of - the single transparent color for - non-paletted images (PNG_INFO_tRNS) - num_trans - number of transparent entries - (PNG_INFO_tRNS) - - png_get_hIST(png_ptr, info_ptr, &hist); - (PNG_INFO_hIST) - hist - histogram of palette (array of - png_uint_16) - - png_get_tIME(png_ptr, info_ptr, &mod_time); - mod_time - time image was last modified - (PNG_VALID_tIME) - - png_get_bKGD(png_ptr, info_ptr, &background); - background - background color (PNG_VALID_bKGD) - valid 16-bit red, green and blue - values, regardless of color_type - - num_comments = png_get_text(png_ptr, info_ptr, - &text_ptr, &num_text); - num_comments - number of comments - text_ptr - array of png_text holding image - comments - text_ptr[i].compression - type of compression used - on "text" PNG_TEXT_COMPRESSION_NONE - PNG_TEXT_COMPRESSION_zTXt - PNG_ITXT_COMPRESSION_NONE - PNG_ITXT_COMPRESSION_zTXt - text_ptr[i].key - keyword for comment. Must contain - 1-79 characters. - text_ptr[i].text - text comments for current - keyword. Can be empty. - text_ptr[i].text_length - length of text string, - after decompression, 0 for iTXt - text_ptr[i].itxt_length - length of itxt string, - after decompression, 0 for tEXt/zTXt - text_ptr[i].lang - language of comment (empty - string for unknown). - text_ptr[i].lang_key - keyword in UTF-8 - (empty string for unknown). - Note that the itxt_length, lang, and lang_key - members of the text_ptr structure only exist - when the library is built with iTXt chunk support. - - num_text - number of comments (same as - num_comments; you can put NULL here - to avoid the duplication) - Note while png_set_text() will accept text, language, - and translated keywords that can be NULL pointers, the - structure returned by png_get_text will always contain - regular zero-terminated C strings. They might be - empty strings but they will never be NULL pointers. - - num_spalettes = png_get_sPLT(png_ptr, info_ptr, - &palette_ptr); - palette_ptr - array of palette structures holding - contents of one or more sPLT chunks - read. - num_spalettes - number of sPLT chunks read. - - png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y, - &unit_type); - offset_x - positive offset from the left edge - of the screen - offset_y - positive offset from the top edge - of the screen - unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER - - png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y, - &unit_type); - res_x - pixels/unit physical resolution in - x direction - res_y - pixels/unit physical resolution in - x direction - unit_type - PNG_RESOLUTION_UNKNOWN, - PNG_RESOLUTION_METER - - png_get_sCAL(png_ptr, info_ptr, &unit, &width, - &height) - unit - physical scale units (an integer) - width - width of a pixel in physical scale units - height - height of a pixel in physical scale units - (width and height are doubles) - - png_get_sCAL_s(png_ptr, info_ptr, &unit, &width, - &height) - unit - physical scale units (an integer) - width - width of a pixel in physical scale units - height - height of a pixel in physical scale units - (width and height are strings like "2.54") - - num_unknown_chunks = png_get_unknown_chunks(png_ptr, - info_ptr, &unknowns) - unknowns - array of png_unknown_chunk - structures holding unknown chunks - unknowns[i].name - name of unknown chunk - unknowns[i].data - data of unknown chunk - unknowns[i].size - size of unknown chunk's data - unknowns[i].location - position of chunk in file - - The value of "i" corresponds to the order in which the - chunks were read from the PNG file or inserted with the - png_set_unknown_chunks() function. - -The data from the pHYs chunk can be retrieved in several convenient -forms: - - res_x = png_get_x_pixels_per_meter(png_ptr, - info_ptr) - res_y = png_get_y_pixels_per_meter(png_ptr, - info_ptr) - res_x_and_y = png_get_pixels_per_meter(png_ptr, - info_ptr) - res_x = png_get_x_pixels_per_inch(png_ptr, - info_ptr) - res_y = png_get_y_pixels_per_inch(png_ptr, - info_ptr) - res_x_and_y = png_get_pixels_per_inch(png_ptr, - info_ptr) - aspect_ratio = png_get_pixel_aspect_ratio(png_ptr, - info_ptr) - - (Each of these returns 0 [signifying "unknown"] if - the data is not present or if res_x is 0; - res_x_and_y is 0 if res_x != res_y) - -The data from the oFFs chunk can be retrieved in several convenient -forms: - - x_offset = png_get_x_offset_microns(png_ptr, info_ptr); - y_offset = png_get_y_offset_microns(png_ptr, info_ptr); - x_offset = png_get_x_offset_inches(png_ptr, info_ptr); - y_offset = png_get_y_offset_inches(png_ptr, info_ptr); - - (Each of these returns 0 [signifying "unknown" if both - x and y are 0] if the data is not present or if the - chunk is present but the unit is the pixel) - -For more information, see the png_info definition in png.h and the -PNG specification for chunk contents. Be careful with trusting -rowbytes, as some of the transformations could increase the space -needed to hold a row (expand, filler, gray_to_rgb, etc.). -See png_read_update_info(), below. - -A quick word about text_ptr and num_text. PNG stores comments in -keyword/text pairs, one pair per chunk, with no limit on the number -of text chunks, and a 2^31 byte limit on their size. While there are -suggested keywords, there is no requirement to restrict the use to these -strings. It is strongly suggested that keywords and text be sensible -to humans (that's the point), so don't use abbreviations. Non-printing -symbols are not allowed. See the PNG specification for more details. -There is also no requirement to have text after the keyword. - -Keywords should be limited to 79 Latin-1 characters without leading or -trailing spaces, but non-consecutive spaces are allowed within the -keyword. It is possible to have the same keyword any number of times. -The text_ptr is an array of png_text structures, each holding a -pointer to a language string, a pointer to a keyword and a pointer to -a text string. The text string, language code, and translated -keyword may be empty or NULL pointers. The keyword/text -pairs are put into the array in the order that they are received. -However, some or all of the text chunks may be after the image, so, to -make sure you have read all the text chunks, don't mess with these -until after you read the stuff after the image. This will be -mentioned again below in the discussion that goes with png_read_end(). - -Input transformations - -After you've read the header information, you can set up the library -to handle any special transformations of the image data. The various -ways to transform the data will be described in the order that they -should occur. This is important, as some of these change the color -type and/or bit depth of the data, and some others only work on -certain color types and bit depths. Even though each transformation -checks to see if it has data that it can do something with, you should -make sure to only enable a transformation if it will be valid for the -data. For example, don't swap red and blue on grayscale data. - -The colors used for the background and transparency values should be -supplied in the same format/depth as the current image data. They -are stored in the same format/depth as the image data in a bKGD or tRNS -chunk, so this is what libpng expects for this data. The colors are -transformed to keep in sync with the image data when an application -calls the png_read_update_info() routine (see below). - -Data will be decoded into the supplied row buffers packed into bytes -unless the library has been told to transform it into another format. -For example, 4 bit/pixel paletted or grayscale data will be returned -2 pixels/byte with the leftmost pixel in the high-order bits of the -byte, unless png_set_packing() is called. 8-bit RGB data will be stored -in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha() -is called to insert filler bytes, either before or after each RGB triplet. -16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant -byte of the color value first, unless png_set_strip_16() is called to -transform it to regular RGB RGB triplets, or png_set_filler() or -png_set_add alpha() is called to insert filler bytes, either before or -after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can -be modified with -png_set_filler(), png_set_add_alpha(), or png_set_strip_16(). - -The following code transforms grayscale images of less than 8 to 8 bits, -changes paletted images to RGB, and adds a full alpha channel if there is -transparency information in a tRNS chunk. This is most useful on -grayscale images with bit depths of 2 or 4 or if there is a multiple-image -viewing application that wishes to treat all images in the same way. - - if (color_type == PNG_COLOR_TYPE_PALETTE) - png_set_palette_to_rgb(png_ptr); - - if (color_type == PNG_COLOR_TYPE_GRAY && - bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr); - - if (png_get_valid(png_ptr, info_ptr, - PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr); - -These three functions are actually aliases for png_set_expand(), added -in libpng version 1.0.4, with the function names expanded to improve code -readability. In some future version they may actually do different -things. - -As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was -added. It expands the sample depth without changing tRNS to alpha. - -As of libpng version 1.4.3, not all possible expansions are supported. - -In the following table, the 01 means grayscale with depth<8, 31 means -indexed with depth<8, other numerals represent the color type, "T" means -the tRNS chunk is present, A means an alpha channel is present, and O -means tRNS or alpha is present but all pixels in the image are opaque. - - FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O - TO - 01 - - 31 - - 0 1 - - 0T - - 0O - - 2 GX - - 2T - - 2O - - 3 1 - - 3T - - 3O - - 4A T - - 4O - - 6A GX TX TX - - 6O GX TX - - -Within the matrix, - "-" means the transformation is not supported. - "X" means the transformation is obtained by png_set_expand(). - "1" means the transformation is obtained by - png_set_expand_gray_1_2_4_to_8 - "G" means the transformation is obtained by - png_set_gray_to_rgb(). - "P" means the transformation is obtained by - png_set_expand_palette_to_rgb(). - "T" means the transformation is obtained by - png_set_tRNS_to_alpha(). - -PNG can have files with 16 bits per channel. If you only can handle -8 bits per channel, this will strip the pixels down to 8 bit. - - if (bit_depth == 16) - png_set_strip_16(png_ptr); - -If, for some reason, you don't need the alpha channel on an image, -and you want to remove it rather than combining it with the background -(but the image author certainly had in mind that you *would* combine -it with the background, so that's what you should probably do): - - if (color_type & PNG_COLOR_MASK_ALPHA) - png_set_strip_alpha(png_ptr); - -In PNG files, the alpha channel in an image -is the level of opacity. If you need the alpha channel in an image to -be the level of transparency instead of opacity, you can invert the -alpha channel (or the tRNS chunk data) after it's read, so that 0 is -fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit -images) is fully transparent, with - - png_set_invert_alpha(png_ptr); - -PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as -they can, resulting in, for example, 8 pixels per byte for 1 bit -files. This code expands to 1 pixel per byte without changing the -values of the pixels: - - if (bit_depth < 8) - png_set_packing(png_ptr); - -PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels -stored in a PNG image have been "scaled" or "shifted" up to the next -higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] -to 8 bits/sample in the range [0, 255]). However, it is also possible -to convert the PNG pixel data back to the original bit depth of the -image. This call reduces the pixels back down to the original bit depth: - - png_color_8p sig_bit; - - if (png_get_sBIT(png_ptr, info_ptr, &sig_bit)) - png_set_shift(png_ptr, sig_bit); - -PNG files store 3-color pixels in red, green, blue order. This code -changes the storage of the pixels to blue, green, red: - - if (color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_RGB_ALPHA) - png_set_bgr(png_ptr); - -PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them -into 4 or 8 bytes for windowing systems that need them in this format: - - if (color_type == PNG_COLOR_TYPE_RGB) - png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE); - -where "filler" is the 8 or 16-bit number to fill with, and the location is -either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether -you want the filler before the RGB or after. This transformation -does not affect images that already have full alpha channels. To add an -opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which -will generate RGBA pixels. - -Note that png_set_filler() does not change the color type. If you want -to do that, you can add a true alpha channel with - - if (color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_GRAY) - png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER); - -where "filler" contains the alpha value to assign to each pixel. -This function was added in libpng-1.2.7. - -If you are reading an image with an alpha channel, and you need the -data as ARGB instead of the normal PNG format RGBA: - - if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) - png_set_swap_alpha(png_ptr); - -For some uses, you may want a grayscale image to be represented as -RGB. This code will do that conversion: - - if (color_type == PNG_COLOR_TYPE_GRAY || - color_type == PNG_COLOR_TYPE_GRAY_ALPHA) - png_set_gray_to_rgb(png_ptr); - -Conversely, you can convert an RGB or RGBA image to grayscale or grayscale -with alpha. - - if (color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_RGB_ALPHA) - png_set_rgb_to_gray_fixed(png_ptr, error_action, - int red_weight, int green_weight); - - error_action = 1: silently do the conversion - error_action = 2: issue a warning if the original - image has any pixel where - red != green or red != blue - error_action = 3: issue an error and abort the - conversion if the original - image has any pixel where - red != green or red != blue - - red_weight: weight of red component times 100000 - green_weight: weight of green component times 100000 - If either weight is negative, default - weights (21268, 71514) are used. - -If you have set error_action = 1 or 2, you can -later check whether the image really was gray, after processing -the image rows, with the png_get_rgb_to_gray_status(png_ptr) function. -It will return a png_byte that is zero if the image was gray or -1 if there were any non-gray pixels. bKGD and sBIT data -will be silently converted to grayscale, using the green channel -data, regardless of the error_action setting. - -With red_weight+green_weight<=100000, -the normalized graylevel is computed: - - int rw = red_weight * 65536; - int gw = green_weight * 65536; - int bw = 65536 - (rw + gw); - gray = (rw*red + gw*green + bw*blue)/65536; - -The default values approximate those recommended in the Charles -Poynton's Color FAQ, -Copyright (c) 1998-01-04 Charles Poynton - - Y = 0.212671 * R + 0.715160 * G + 0.072169 * B - -Libpng approximates this with - - Y = 0.21268 * R + 0.7151 * G + 0.07217 * B - -which can be expressed with integers as - - Y = (6969 * R + 23434 * G + 2365 * B)/32768 - -The calculation is done in a linear colorspace, if the image gamma -is known. - -If you have a grayscale and you are using png_set_expand_depth(), -png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to -a higher bit-depth, you must either supply the background color as a gray -value at the original file bit-depth (need_expand = 1) or else supply the -background color as an RGB triplet at the final, expanded bit depth -(need_expand = 0). Similarly, if you are reading a paletted image, you -must either supply the background color as a palette index (need_expand = 1) -or as an RGB triplet that may or may not be in the palette (need_expand = 0). - - png_color_16 my_background; - png_color_16p image_background; - - if (png_get_bKGD(png_ptr, info_ptr, &image_background)) - png_set_background(png_ptr, image_background, - PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); - else - png_set_background(png_ptr, &my_background, - PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); - -The png_set_background() function tells libpng to composite images -with alpha or simple transparency against the supplied background -color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid), -you may use this color, or supply another color more suitable for -the current display (e.g., the background color from a web page). You -need to tell libpng whether the color is in the gamma space of the -display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file -(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one -that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't -know why anyone would use this, but it's here). - -To properly display PNG images on any kind of system, the application needs -to know what the display gamma is. Ideally, the user will know this, and -the application will allow them to set it. One method of allowing the user -to set the display gamma separately for each system is to check for a -SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be -correctly set. - -Note that display_gamma is the overall gamma correction required to produce -pleasing results, which depends on the lighting conditions in the surrounding -environment. In a dim or brightly lit room, no compensation other than -the physical gamma exponent of the monitor is needed, while in a dark room -a slightly smaller exponent is better. - - double gamma, screen_gamma; - - if (/* We have a user-defined screen - gamma value */) - { - screen_gamma = user_defined_screen_gamma; - } - /* One way that applications can share the same - screen gamma value */ - else if ((gamma_str = getenv("SCREEN_GAMMA")) - != NULL) - { - screen_gamma = (double)atof(gamma_str); - } - /* If we don't have another value */ - else - { - screen_gamma = 2.2; /* A good guess for a - PC monitor in a bright office or a dim room */ - screen_gamma = 2.0; /* A good guess for a - PC monitor in a dark room */ - screen_gamma = 1.7 or 1.0; /* A good - guess for Mac systems */ - } - -The png_set_gamma() function handles gamma transformations of the data. -Pass both the file gamma and the current screen_gamma. If the file does -not have a gamma value, you can pass one anyway if you have an idea what -it is (usually 0.45455 is a good guess for GIF images on PCs). Note -that file gammas are inverted from screen gammas. See the discussions -on gamma in the PNG specification for an excellent description of what -gamma is, and why all applications should support it. It is strongly -recommended that PNG viewers support gamma correction. - - if (png_get_gAMA(png_ptr, info_ptr, &gamma)) - png_set_gamma(png_ptr, screen_gamma, gamma); - else - png_set_gamma(png_ptr, screen_gamma, 0.45455); - -If you need to reduce an RGB file to a paletted file, or if a paletted -file has more entries then will fit on your screen, png_set_quantize() -will do that. Note that this is a simple match dither that merely -finds the closest color available. This should work fairly well with -optimized palettes, and fairly badly with linear color cubes. If you -pass a palette that is larger then maximum_colors, the file will -reduce the number of colors in the palette so it will fit into -maximum_colors. If there is a histogram, it will use it to make -more intelligent choices when reducing the palette. If there is no -histogram, it may not do as good a job. - - if (color_type & PNG_COLOR_MASK_COLOR) - { - if (png_get_valid(png_ptr, info_ptr, - PNG_INFO_PLTE)) - { - png_uint_16p histogram = NULL; - - png_get_hIST(png_ptr, info_ptr, - &histogram); - png_set_quantize(png_ptr, palette, num_palette, - max_screen_colors, histogram, 1); - } - else - { - png_color std_color_cube[MAX_SCREEN_COLORS] = - { ... colors ... }; - - png_set_quantize(png_ptr, std_color_cube, - MAX_SCREEN_COLORS, MAX_SCREEN_COLORS, - NULL,0); - } - } - -PNG files describe monochrome as black being zero and white being one. -The following code will reverse this (make black be one and white be -zero): - - if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY) - png_set_invert_mono(png_ptr); - -This function can also be used to invert grayscale and gray-alpha images: - - if (color_type == PNG_COLOR_TYPE_GRAY || - color_type == PNG_COLOR_TYPE_GRAY_ALPHA) - png_set_invert_mono(png_ptr); - -PNG files store 16 bit pixels in network byte order (big-endian, -ie. most significant bits first). This code changes the storage to the -other way (little-endian, i.e. least significant bits first, the -way PCs store them): - - if (bit_depth == 16) - png_set_swap(png_ptr); - -If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you -need to change the order the pixels are packed into bytes, you can use: - - if (bit_depth < 8) - png_set_packswap(png_ptr); - -Finally, you can write your own transformation function if none of -the existing ones meets your needs. This is done by setting a callback -with - - png_set_read_user_transform_fn(png_ptr, - read_transform_fn); - -You must supply the function - - void read_transform_fn(png_ptr ptr, row_info_ptr - row_info, png_bytep data) - -See pngtest.c for a working example. Your function will be called -after all of the other transformations have been processed. - -You can also set up a pointer to a user structure for use by your -callback function, and you can inform libpng that your transform -function will change the number of channels or bit depth with the -function - - png_set_user_transform_info(png_ptr, user_ptr, - user_depth, user_channels); - -The user's application, not libpng, is responsible for allocating and -freeing any memory required for the user structure. - -You can retrieve the pointer via the function -png_get_user_transform_ptr(). For example: - - voidp read_user_transform_ptr = - png_get_user_transform_ptr(png_ptr); - -The last thing to handle is interlacing; this is covered in detail below, -but you must call the function here if you want libpng to handle expansion -of the interlaced image. - - number_of_passes = png_set_interlace_handling(png_ptr); - -After setting the transformations, libpng can update your png_info -structure to reflect any transformations you've requested with this -call. This is most useful to update the info structure's rowbytes -field so you can use it to allocate your image memory. This function -will also update your palette with the correct screen_gamma and -background if these have been given with the calls above. - - png_read_update_info(png_ptr, info_ptr); - -After you call png_read_update_info(), you can allocate any -memory you need to hold the image. The row data is simply -raw byte data for all forms of images. As the actual allocation -varies among applications, no example will be given. If you -are allocating one large chunk, you will need to build an -array of pointers to each row, as it will be needed for some -of the functions below. - -Reading image data - -After you've allocated memory, you can read the image data. -The simplest way to do this is in one function call. If you are -allocating enough memory to hold the whole image, you can just -call png_read_image() and libpng will read in all the image data -and put it in the memory area supplied. You will need to pass in -an array of pointers to each row. - -This function automatically handles interlacing, so you don't need -to call png_set_interlace_handling() or call this function multiple -times, or any of that other stuff necessary with png_read_rows(). - - png_read_image(png_ptr, row_pointers); - -where row_pointers is: - - png_bytep row_pointers[height]; - -You can point to void or char or whatever you use for pixels. - -If you don't want to read in the whole image at once, you can -use png_read_rows() instead. If there is no interlacing (check -interlace_type == PNG_INTERLACE_NONE), this is simple: - - png_read_rows(png_ptr, row_pointers, NULL, - number_of_rows); - -where row_pointers is the same as in the png_read_image() call. - -If you are doing this just one row at a time, you can do this with -a single row_pointer instead of an array of row_pointers: - - png_bytep row_pointer = row; - png_read_row(png_ptr, row_pointer, NULL); - -If the file is interlaced (interlace_type != 0 in the IHDR chunk), things -get somewhat harder. The only current (PNG Specification version 1.2) -interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7) -is a somewhat complicated 2D interlace scheme, known as Adam7, that -breaks down an image into seven smaller images of varying size, based -on an 8x8 grid. - -libpng can fill out those images or it can give them to you "as is". -If you want them filled out, there are two ways to do that. The one -mentioned in the PNG specification is to expand each pixel to cover -those pixels that have not been read yet (the "rectangle" method). -This results in a blocky image for the first pass, which gradually -smooths out as more pixels are read. The other method is the "sparkle" -method, where pixels are drawn only in their final locations, with the -rest of the image remaining whatever colors they were initialized to -before the start of the read. The first method usually looks better, -but tends to be slower, as there are more pixels to put in the rows. - -If you don't want libpng to handle the interlacing details, just call -png_read_rows() seven times to read in all seven images. Each of the -images is a valid image by itself, or they can all be combined on an -8x8 grid to form a single image (although if you intend to combine them -you would be far better off using the libpng interlace handling). - -The first pass will return an image 1/8 as wide as the entire image -(every 8th column starting in column 0) and 1/8 as high as the original -(every 8th row starting in row 0), the second will be 1/8 as wide -(starting in column 4) and 1/8 as high (also starting in row 0). The -third pass will be 1/4 as wide (every 4th pixel starting in column 0) and -1/8 as high (every 8th row starting in row 4), and the fourth pass will -be 1/4 as wide and 1/4 as high (every 4th column starting in column 2, -and every 4th row starting in row 0). The fifth pass will return an -image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2), -while the sixth pass will be 1/2 as wide and 1/2 as high as the original -(starting in column 1 and row 0). The seventh and final pass will be as -wide as the original, and 1/2 as high, containing all of the odd -numbered scanlines. Phew! - -If you want libpng to expand the images, call this before calling -png_start_read_image() or png_read_update_info(): - - if (interlace_type == PNG_INTERLACE_ADAM7) - number_of_passes - = png_set_interlace_handling(png_ptr); - -This will return the number of passes needed. Currently, this -is seven, but may change if another interlace type is added. -This function can be called even if the file is not interlaced, -where it will return one pass. - -If you are not going to display the image after each pass, but are -going to wait until the entire image is read in, use the sparkle -effect. This effect is faster and the end result of either method -is exactly the same. If you are planning on displaying the image -after each pass, the "rectangle" effect is generally considered the -better looking one. - -If you only want the "sparkle" effect, just call png_read_rows() as -normal, with the third parameter NULL. Make sure you make pass over -the image number_of_passes times, and you don't change the data in the -rows between calls. You can change the locations of the data, just -not the data. Each pass only writes the pixels appropriate for that -pass, and assumes the data from previous passes is still valid. - - png_read_rows(png_ptr, row_pointers, NULL, - number_of_rows); - -If you only want the first effect (the rectangles), do the same as -before except pass the row buffer in the third parameter, and leave -the second parameter NULL. - - png_read_rows(png_ptr, NULL, row_pointers, - number_of_rows); - -Finishing a sequential read - -After you are finished reading the image through the -low-level interface, you can finish reading the file. If you are -interested in comments or time, which may be stored either before or -after the image data, you should pass the separate png_info struct if -you want to keep the comments from before and after the image -separate. If you are not interested, you can pass NULL. - - png_read_end(png_ptr, end_info); - -When you are done, you can free all memory allocated by libpng like this: - - png_destroy_read_struct(&png_ptr, &info_ptr, - &end_info); - -It is also possible to individually free the info_ptr members that -point to libpng-allocated storage with the following function: - - png_free_data(png_ptr, info_ptr, mask, seq) - mask - identifies data to be freed, a mask - containing the bitwise OR of one or - more of - PNG_FREE_PLTE, PNG_FREE_TRNS, - PNG_FREE_HIST, PNG_FREE_ICCP, - PNG_FREE_PCAL, PNG_FREE_ROWS, - PNG_FREE_SCAL, PNG_FREE_SPLT, - PNG_FREE_TEXT, PNG_FREE_UNKN, - or simply PNG_FREE_ALL - seq - sequence number of item to be freed - (-1 for all items) - -This function may be safely called when the relevant storage has -already been freed, or has not yet been allocated, or was allocated -by the user and not by libpng, and will in those cases do nothing. -The "seq" parameter is ignored if only one item of the selected data -type, such as PLTE, is allowed. If "seq" is not -1, and multiple items -are allowed for the data type identified in the mask, such as text or -sPLT, only the n'th item in the structure is freed, where n is "seq". - -The default behavior is only to free data that was allocated internally -by libpng. This can be changed, so that libpng will not free the data, -or so that it will free data that was allocated by the user with png_malloc() -or png_zalloc() and passed in via a png_set_*() function, with - - png_data_freer(png_ptr, info_ptr, freer, mask) - mask - which data elements are affected - same choices as in png_free_data() - freer - one of - PNG_DESTROY_WILL_FREE_DATA - PNG_SET_WILL_FREE_DATA - PNG_USER_WILL_FREE_DATA - -This function only affects data that has already been allocated. -You can call this function after reading the PNG data but before calling -any png_set_*() functions, to control whether the user or the png_set_*() -function is responsible for freeing any existing data that might be present, -and again after the png_set_*() functions to control whether the user -or png_destroy_*() is supposed to free the data. When the user assumes -responsibility for libpng-allocated data, the application must use -png_free() to free it, and when the user transfers responsibility to libpng -for data that the user has allocated, the user must have used png_malloc() -or png_zalloc() to allocate it. - -If you allocated your row_pointers in a single block, as suggested above in -the description of the high level read interface, you must not transfer -responsibility for freeing it to the png_set_rows or png_read_destroy function, -because they would also try to free the individual row_pointers[i]. - -If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword -separately, do not transfer responsibility for freeing text_ptr to libpng, -because when libpng fills a png_text structure it combines these members with -the key member, and png_free_data() will free only text_ptr.key. Similarly, -if you transfer responsibility for free'ing text_ptr from libpng to your -application, your application must not separately free those members. - -The png_free_data() function will turn off the "valid" flag for anything -it frees. If you need to turn the flag off for a chunk that was freed by -your application instead of by libpng, you can use - - png_set_invalid(png_ptr, info_ptr, mask); - mask - identifies the chunks to be made invalid, - containing the bitwise OR of one or - more of - PNG_INFO_gAMA, PNG_INFO_sBIT, - PNG_INFO_cHRM, PNG_INFO_PLTE, - PNG_INFO_tRNS, PNG_INFO_bKGD, - PNG_INFO_hIST, PNG_INFO_pHYs, - PNG_INFO_oFFs, PNG_INFO_tIME, - PNG_INFO_pCAL, PNG_INFO_sRGB, - PNG_INFO_iCCP, PNG_INFO_sPLT, - PNG_INFO_sCAL, PNG_INFO_IDAT - -For a more compact example of reading a PNG image, see the file example.c. - -Reading PNG files progressively - -The progressive reader is slightly different then the non-progressive -reader. Instead of calling png_read_info(), png_read_rows(), and -png_read_end(), you make one call to png_process_data(), which calls -callbacks when it has the info, a row, or the end of the image. You -set up these callbacks with png_set_progressive_read_fn(). You don't -have to worry about the input/output functions of libpng, as you are -giving the library the data directly in png_process_data(). I will -assume that you have read the section on reading PNG files above, -so I will only highlight the differences (although I will show -all of the code). - -png_structp png_ptr; -png_infop info_ptr; - - /* An example code fragment of how you would - initialize the progressive reader in your - application. */ - int - initialize_png_reader() - { - png_ptr = png_create_read_struct - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, - user_error_fn, user_warning_fn); - if (!png_ptr) - return (ERROR); - info_ptr = png_create_info_struct(png_ptr); - if (!info_ptr) - { - png_destroy_read_struct(&png_ptr, (png_infopp)NULL, - (png_infopp)NULL); - return (ERROR); - } - - if (setjmp(png_jmpbuf(png_ptr))) - { - png_destroy_read_struct(&png_ptr, &info_ptr, - (png_infopp)NULL); - return (ERROR); - } - - /* This one's new. You can provide functions - to be called when the header info is valid, - when each row is completed, and when the image - is finished. If you aren't using all functions, - you can specify NULL parameters. Even when all - three functions are NULL, you need to call - png_set_progressive_read_fn(). You can use - any struct as the user_ptr (cast to a void pointer - for the function call), and retrieve the pointer - from inside the callbacks using the function - - png_get_progressive_ptr(png_ptr); - - which will return a void pointer, which you have - to cast appropriately. - */ - png_set_progressive_read_fn(png_ptr, (void *)user_ptr, - info_callback, row_callback, end_callback); - - return 0; - } - - /* A code fragment that you call as you receive blocks - of data */ - int - process_data(png_bytep buffer, png_uint_32 length) - { - if (setjmp(png_jmpbuf(png_ptr))) - { - png_destroy_read_struct(&png_ptr, &info_ptr, - (png_infopp)NULL); - return (ERROR); - } - - /* This one's new also. Simply give it a chunk - of data from the file stream (in order, of - course). On machines with segmented memory - models machines, don't give it any more than - 64K. The library seems to run fine with sizes - of 4K. Although you can give it much less if - necessary (I assume you can give it chunks of - 1 byte, I haven't tried less then 256 bytes - yet). When this function returns, you may - want to display any rows that were generated - in the row callback if you don't already do - so there. - */ - png_process_data(png_ptr, info_ptr, buffer, length); - return 0; - } - - /* This function is called (as set by - png_set_progressive_read_fn() above) when enough data - has been supplied so all of the header has been - read. - */ - void - info_callback(png_structp png_ptr, png_infop info) - { - /* Do any setup here, including setting any of - the transformations mentioned in the Reading - PNG files section. For now, you _must_ call - either png_start_read_image() or - png_read_update_info() after all the - transformations are set (even if you don't set - any). You may start getting rows before - png_process_data() returns, so this is your - last chance to prepare for that. - */ - } - - /* This function is called when each row of image - data is complete */ - void - row_callback(png_structp png_ptr, png_bytep new_row, - png_uint_32 row_num, int pass) - { - /* If the image is interlaced, and you turned - on the interlace handler, this function will - be called for every row in every pass. Some - of these rows will not be changed from the - previous pass. When the row is not changed, - the new_row variable will be NULL. The rows - and passes are called in order, so you don't - really need the row_num and pass, but I'm - supplying them because it may make your life - easier. - - For the non-NULL rows of interlaced images, - you must call png_progressive_combine_row() - passing in the row and the old row. You can - call this function for NULL rows (it will just - return) and for non-interlaced images (it just - does the memcpy for you) if it will make the - code easier. Thus, you can just do this for - all cases: - */ - - png_progressive_combine_row(png_ptr, old_row, - new_row); - - /* where old_row is what was displayed for - previously for the row. Note that the first - pass (pass == 0, really) will completely cover - the old row, so the rows do not have to be - initialized. After the first pass (and only - for interlaced images), you will have to pass - the current row, and the function will combine - the old row and the new row. - */ - } - - void - end_callback(png_structp png_ptr, png_infop info) - { - /* This function is called after the whole image - has been read, including any chunks after the - image (up to and including the IEND). You - will usually have the same info chunk as you - had in the header, although some data may have - been added to the comments and time fields. - - Most people won't do much here, perhaps setting - a flag that marks the image as finished. - */ - } - - - -IV. Writing - -Much of this is very similar to reading. However, everything of -importance is repeated here, so you won't have to constantly look -back up in the reading section to understand writing. - -Setup - -You will want to do the I/O initialization before you get into libpng, -so if it doesn't work, you don't have anything to undo. If you are not -using the standard I/O functions, you will need to replace them with -custom writing functions. See the discussion under Customizing libpng. - - FILE *fp = fopen(file_name, "wb"); - if (!fp) - { - return (ERROR); - } - -Next, png_struct and png_info need to be allocated and initialized. -As these can be both relatively large, you may not want to store these -on the stack, unless you have stack space to spare. Of course, you -will want to check if they return NULL. If you are also reading, -you won't want to name your read structure and your write structure -both "png_ptr"; you can call them anything you like, such as -"read_ptr" and "write_ptr". Look at pngtest.c, for example. - - png_structp png_ptr = png_create_write_struct - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, - user_error_fn, user_warning_fn); - if (!png_ptr) - return (ERROR); - - png_infop info_ptr = png_create_info_struct(png_ptr); - if (!info_ptr) - { - png_destroy_write_struct(&png_ptr, - (png_infopp)NULL); - return (ERROR); - } - -If you want to use your own memory allocation routines, -define PNG_USER_MEM_SUPPORTED and use -png_create_write_struct_2() instead of png_create_write_struct(): - - png_structp png_ptr = png_create_write_struct_2 - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, - user_error_fn, user_warning_fn, (png_voidp) - user_mem_ptr, user_malloc_fn, user_free_fn); - -After you have these structures, you will need to set up the -error handling. When libpng encounters an error, it expects to -longjmp() back to your routine. Therefore, you will need to call -setjmp() and pass the png_jmpbuf(png_ptr). If you -write the file from different routines, you will need to update -the png_jmpbuf(png_ptr) every time you enter a new routine that will -call a png_*() function. See your documentation of setjmp/longjmp -for your compiler for more information on setjmp/longjmp. See -the discussion on libpng error handling in the Customizing Libpng -section below for more information on the libpng error handling. - - if (setjmp(png_jmpbuf(png_ptr))) - { - png_destroy_write_struct(&png_ptr, &info_ptr); - fclose(fp); - return (ERROR); - } - ... - return; - -If you would rather avoid the complexity of setjmp/longjmp issues, -you can compile libpng with PNG_NO_SETJMP, in which case -errors will result in a call to PNG_ABORT() which defaults to abort(). - -You can #define PNG_ABORT() to a function that does something -more useful than abort(), as long as your function does not -return. - -Now you need to set up the output code. The default for libpng is to -use the C function fwrite(). If you use this, you will need to pass a -valid FILE * in the function png_init_io(). Be sure that the file is -opened in binary mode. Again, if you wish to handle writing data in -another way, see the discussion on libpng I/O handling in the Customizing -Libpng section below. - - png_init_io(png_ptr, fp); - -If you are embedding your PNG into a datastream such as MNG, and don't -want libpng to write the 8-byte signature, or if you have already -written the signature in your application, use - - png_set_sig_bytes(png_ptr, 8); - -to inform libpng that it should not write a signature. - -Write callbacks - -At this point, you can set up a callback function that will be -called after each row has been written, which you can use to control -a progress meter or the like. It's demonstrated in pngtest.c. -You must supply a function - - void write_row_callback(png_ptr, png_uint_32 row, - int pass); - { - /* put your code here */ - } - -(You can give it another name that you like instead of "write_row_callback") - -To inform libpng about your function, use - - png_set_write_status_fn(png_ptr, write_row_callback); - -You now have the option of modifying how the compression library will -run. The following functions are mainly for testing, but may be useful -in some cases, like if you need to write PNG files extremely fast and -are willing to give up some compression, or if you want to get the -maximum possible compression at the expense of slower writing. If you -have no special needs in this area, let the library do what it wants by -not calling this function at all, as it has been tuned to deliver a good -speed/compression ratio. The second parameter to png_set_filter() is -the filter method, for which the only valid values are 0 (as of the -July 1999 PNG specification, version 1.2) or 64 (if you are writing -a PNG datastream that is to be embedded in a MNG datastream). The third -parameter is a flag that indicates which filter type(s) are to be tested -for each scanline. See the PNG specification for details on the specific -filter types. - - - /* turn on or off filtering, and/or choose - specific filters. You can use either a single - PNG_FILTER_VALUE_NAME or the bitwise OR of one - or more PNG_FILTER_NAME masks. */ - png_set_filter(png_ptr, 0, - PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE | - PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB | - PNG_FILTER_UP | PNG_FILTER_VALUE_UP | - PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG | - PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH| - PNG_ALL_FILTERS); - -If an application -wants to start and stop using particular filters during compression, -it should start out with all of the filters (to ensure that the previous -row of pixels will be stored in case it's needed later), and then add -and remove them after the start of compression. - -If you are writing a PNG datastream that is to be embedded in a MNG -datastream, the second parameter can be either 0 or 64. - -The png_set_compression_*() functions interface to the zlib compression -library, and should mostly be ignored unless you really know what you are -doing. The only generally useful call is png_set_compression_level() -which changes how much time zlib spends on trying to compress the image -data. See the Compression Library (zlib.h and algorithm.txt, distributed -with zlib) for details on the compression levels. - - /* set the zlib compression level */ - png_set_compression_level(png_ptr, - Z_BEST_COMPRESSION); - - /* set other zlib parameters */ - png_set_compression_mem_level(png_ptr, 8); - png_set_compression_strategy(png_ptr, - Z_DEFAULT_STRATEGY); - png_set_compression_window_bits(png_ptr, 15); - png_set_compression_method(png_ptr, 8); - png_set_compression_buffer_size(png_ptr, 8192) - -extern PNG_EXPORT(void,png_set_zbuf_size) - -Setting the contents of info for output - -You now need to fill in the png_info structure with all the data you -wish to write before the actual image. Note that the only thing you -are allowed to write after the image is the text chunks and the time -chunk (as of PNG Specification 1.2, anyway). See png_write_end() and -the latest PNG specification for more information on that. If you -wish to write them before the image, fill them in now, and flag that -data as being valid. If you want to wait until after the data, don't -fill them until png_write_end(). For all the fields in png_info and -their data types, see png.h. For explanations of what the fields -contain, see the PNG specification. - -Some of the more important parts of the png_info are: - - png_set_IHDR(png_ptr, info_ptr, width, height, - bit_depth, color_type, interlace_type, - compression_type, filter_method) - width - holds the width of the image - in pixels (up to 2^31). - height - holds the height of the image - in pixels (up to 2^31). - bit_depth - holds the bit depth of one of the - image channels. - (valid values are 1, 2, 4, 8, 16 - and depend also on the - color_type. See also significant - bits (sBIT) below). - color_type - describes which color/alpha - channels are present. - PNG_COLOR_TYPE_GRAY - (bit depths 1, 2, 4, 8, 16) - PNG_COLOR_TYPE_GRAY_ALPHA - (bit depths 8, 16) - PNG_COLOR_TYPE_PALETTE - (bit depths 1, 2, 4, 8) - PNG_COLOR_TYPE_RGB - (bit_depths 8, 16) - PNG_COLOR_TYPE_RGB_ALPHA - (bit_depths 8, 16) - - PNG_COLOR_MASK_PALETTE - PNG_COLOR_MASK_COLOR - PNG_COLOR_MASK_ALPHA - - interlace_type - PNG_INTERLACE_NONE or - PNG_INTERLACE_ADAM7 - compression_type - (must be - PNG_COMPRESSION_TYPE_DEFAULT) - filter_method - (must be PNG_FILTER_TYPE_DEFAULT - or, if you are writing a PNG to - be embedded in a MNG datastream, - can also be - PNG_INTRAPIXEL_DIFFERENCING) - -If you call png_set_IHDR(), the call must appear before any of the -other png_set_*() functions, because they might require access to some of -the IHDR settings. The remaining png_set_*() functions can be called -in any order. - -If you wish, you can reset the compression_type, interlace_type, or -filter_method later by calling png_set_IHDR() again; if you do this, the -width, height, bit_depth, and color_type must be the same in each call. - - png_set_PLTE(png_ptr, info_ptr, palette, - num_palette); - palette - the palette for the file - (array of png_color) - num_palette - number of entries in the palette - - png_set_gAMA(png_ptr, info_ptr, gamma); - gamma - the gamma the image was created - at (PNG_INFO_gAMA) - - png_set_sRGB(png_ptr, info_ptr, srgb_intent); - srgb_intent - the rendering intent - (PNG_INFO_sRGB) The presence of - the sRGB chunk means that the pixel - data is in the sRGB color space. - This chunk also implies specific - values of gAMA and cHRM. Rendering - intent is the CSS-1 property that - has been defined by the International - Color Consortium - (http://www.color.org). - It can be one of - PNG_sRGB_INTENT_SATURATION, - PNG_sRGB_INTENT_PERCEPTUAL, - PNG_sRGB_INTENT_ABSOLUTE, or - PNG_sRGB_INTENT_RELATIVE. - - - png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, - srgb_intent); - srgb_intent - the rendering intent - (PNG_INFO_sRGB) The presence of the - sRGB chunk means that the pixel - data is in the sRGB color space. - This function also causes gAMA and - cHRM chunks with the specific values - that are consistent with sRGB to be - written. - - png_set_iCCP(png_ptr, info_ptr, name, compression_type, - profile, proflen); - name - The profile name. - compression - The compression type; always - PNG_COMPRESSION_TYPE_BASE for PNG 1.0. - You may give NULL to this argument to - ignore it. - profile - International Color Consortium color - profile data. May contain NULs. - proflen - length of profile data in bytes. - - png_set_sBIT(png_ptr, info_ptr, sig_bit); - sig_bit - the number of significant bits for - (PNG_INFO_sBIT) each of the gray, red, - green, and blue channels, whichever are - appropriate for the given color type - (png_color_16) - - png_set_tRNS(png_ptr, info_ptr, trans_alpha, - num_trans, trans_color); - trans_alpha - array of alpha (transparency) - entries for palette (PNG_INFO_tRNS) - trans_color - graylevel or color sample values - (in order red, green, blue) of the - single transparent color for - non-paletted images (PNG_INFO_tRNS) - num_trans - number of transparent entries - (PNG_INFO_tRNS) - - png_set_hIST(png_ptr, info_ptr, hist); - (PNG_INFO_hIST) - hist - histogram of palette (array of - png_uint_16) - - png_set_tIME(png_ptr, info_ptr, mod_time); - mod_time - time image was last modified - (PNG_VALID_tIME) - - png_set_bKGD(png_ptr, info_ptr, background); - background - background color (PNG_VALID_bKGD) - - png_set_text(png_ptr, info_ptr, text_ptr, num_text); - text_ptr - array of png_text holding image - comments - text_ptr[i].compression - type of compression used - on "text" PNG_TEXT_COMPRESSION_NONE - PNG_TEXT_COMPRESSION_zTXt - PNG_ITXT_COMPRESSION_NONE - PNG_ITXT_COMPRESSION_zTXt - text_ptr[i].key - keyword for comment. Must contain - 1-79 characters. - text_ptr[i].text - text comments for current - keyword. Can be NULL or empty. - text_ptr[i].text_length - length of text string, - after decompression, 0 for iTXt - text_ptr[i].itxt_length - length of itxt string, - after decompression, 0 for tEXt/zTXt - text_ptr[i].lang - language of comment (NULL or - empty for unknown). - text_ptr[i].translated_keyword - keyword in UTF-8 (NULL - or empty for unknown). - Note that the itxt_length, lang, and lang_key - members of the text_ptr structure only exist - when the library is built with iTXt chunk support. - - num_text - number of comments - - png_set_sPLT(png_ptr, info_ptr, &palette_ptr, - num_spalettes); - palette_ptr - array of png_sPLT_struct structures - to be added to the list of palettes - in the info structure. - num_spalettes - number of palette structures to be - added. - - png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, - unit_type); - offset_x - positive offset from the left - edge of the screen - offset_y - positive offset from the top - edge of the screen - unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER - - png_set_pHYs(png_ptr, info_ptr, res_x, res_y, - unit_type); - res_x - pixels/unit physical resolution - in x direction - res_y - pixels/unit physical resolution - in y direction - unit_type - PNG_RESOLUTION_UNKNOWN, - PNG_RESOLUTION_METER - - png_set_sCAL(png_ptr, info_ptr, unit, width, height) - unit - physical scale units (an integer) - width - width of a pixel in physical scale units - height - height of a pixel in physical scale units - (width and height are doubles) - - png_set_sCAL_s(png_ptr, info_ptr, unit, width, height) - unit - physical scale units (an integer) - width - width of a pixel in physical scale units - height - height of a pixel in physical scale units - (width and height are strings like "2.54") - - png_set_unknown_chunks(png_ptr, info_ptr, &unknowns, - num_unknowns) - unknowns - array of png_unknown_chunk - structures holding unknown chunks - unknowns[i].name - name of unknown chunk - unknowns[i].data - data of unknown chunk - unknowns[i].size - size of unknown chunk's data - unknowns[i].location - position to write chunk in file - 0: do not write chunk - PNG_HAVE_IHDR: before PLTE - PNG_HAVE_PLTE: before IDAT - PNG_AFTER_IDAT: after IDAT - -The "location" member is set automatically according to -what part of the output file has already been written. -You can change its value after calling png_set_unknown_chunks() -as demonstrated in pngtest.c. Within each of the "locations", -the chunks are sequenced according to their position in the -structure (that is, the value of "i", which is the order in which -the chunk was either read from the input file or defined with -png_set_unknown_chunks). - -A quick word about text and num_text. text is an array of png_text -structures. num_text is the number of valid structures in the array. -Each png_text structure holds a language code, a keyword, a text value, -and a compression type. - -The compression types have the same valid numbers as the compression -types of the image data. Currently, the only valid number is zero. -However, you can store text either compressed or uncompressed, unlike -images, which always have to be compressed. So if you don't want the -text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE. -Because tEXt and zTXt chunks don't have a language field, if you -specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt -any language code or translated keyword will not be written out. - -Until text gets around 1000 bytes, it is not worth compressing it. -After the text has been written out to the file, the compression type -is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR, -so that it isn't written out again at the end (in case you are calling -png_write_end() with the same struct. - -The keywords that are given in the PNG Specification are: - - Title Short (one line) title or - caption for image - Author Name of image's creator - Description Description of image (possibly long) - Copyright Copyright notice - Creation Time Time of original image creation - (usually RFC 1123 format, see below) - Software Software used to create the image - Disclaimer Legal disclaimer - Warning Warning of nature of content - Source Device used to create the image - Comment Miscellaneous comment; conversion - from other image format - -The keyword-text pairs work like this. Keywords should be short -simple descriptions of what the comment is about. Some typical -keywords are found in the PNG specification, as is some recommendations -on keywords. You can repeat keywords in a file. You can even write -some text before the image and some after. For example, you may want -to put a description of the image before the image, but leave the -disclaimer until after, so viewers working over modem connections -don't have to wait for the disclaimer to go over the modem before -they start seeing the image. Finally, keywords should be full -words, not abbreviations. Keywords and text are in the ISO 8859-1 -(Latin-1) character set (a superset of regular ASCII) and can not -contain NUL characters, and should not contain control or other -unprintable characters. To make the comments widely readable, stick -with basic ASCII, and avoid machine specific character set extensions -like the IBM-PC character set. The keyword must be present, but -you can leave off the text string on non-compressed pairs. -Compressed pairs must have a text string, as only the text string -is compressed anyway, so the compression would be meaningless. - -PNG supports modification time via the png_time structure. Two -conversion routines are provided, png_convert_from_time_t() for -time_t and png_convert_from_struct_tm() for struct tm. The -time_t routine uses gmtime(). You don't have to use either of -these, but if you wish to fill in the png_time structure directly, -you should provide the time in universal time (GMT) if possible -instead of your local time. Note that the year number is the full -year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and -that months start with 1. - -If you want to store the time of the original image creation, you should -use a plain tEXt chunk with the "Creation Time" keyword. This is -necessary because the "creation time" of a PNG image is somewhat vague, -depending on whether you mean the PNG file, the time the image was -created in a non-PNG format, a still photo from which the image was -scanned, or possibly the subject matter itself. In order to facilitate -machine-readable dates, it is recommended that the "Creation Time" -tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"), -although this isn't a requirement. Unlike the tIME chunk, the -"Creation Time" tEXt chunk is not expected to be automatically changed -by the software. To facilitate the use of RFC 1123 dates, a function -png_convert_to_rfc1123(png_timep) is provided to convert from PNG -time to an RFC 1123 format string. - -Writing unknown chunks - -You can use the png_set_unknown_chunks function to queue up chunks -for writing. You give it a chunk name, raw data, and a size; that's -all there is to it. The chunks will be written by the next following -png_write_info_before_PLTE, png_write_info, or png_write_end function. -Any chunks previously read into the info structure's unknown-chunk -list will also be written out in a sequence that satisfies the PNG -specification's ordering rules. - -The high-level write interface - -At this point there are two ways to proceed; through the high-level -write interface, or through a sequence of low-level write operations. -You can use the high-level interface if your image data is present -in the info structure. All defined output -transformations are permitted, enabled by the following masks. - - PNG_TRANSFORM_IDENTITY No transformation - PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples - PNG_TRANSFORM_PACKSWAP Change order of packed - pixels to LSB first - PNG_TRANSFORM_INVERT_MONO Invert monochrome images - PNG_TRANSFORM_SHIFT Normalize pixels to the - sBIT depth - PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA - to BGRA - PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA - to AG - PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity - to transparency - PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples - PNG_TRANSFORM_STRIP_FILLER Strip out filler - bytes (deprecated). - PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading - filler bytes - PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing - filler bytes - -If you have valid image data in the info structure (you can use -png_set_rows() to put image data in the info structure), simply do this: - - png_write_png(png_ptr, info_ptr, png_transforms, NULL) - -where png_transforms is an integer containing the bitwise OR of some set of -transformation flags. This call is equivalent to png_write_info(), -followed the set of transformations indicated by the transform mask, -then png_write_image(), and finally png_write_end(). - -(The final parameter of this call is not yet used. Someday it might point -to transformation parameters required by some future output transform.) - -You must use png_transforms and not call any png_set_transform() functions -when you use png_write_png(). - -The low-level write interface - -If you are going the low-level route instead, you are now ready to -write all the file information up to the actual image data. You do -this with a call to png_write_info(). - - png_write_info(png_ptr, info_ptr); - -Note that there is one transformation you may need to do before -png_write_info(). In PNG files, the alpha channel in an image is the -level of opacity. If your data is supplied as a level of transparency, -you can invert the alpha channel before you write it, so that 0 is -fully transparent and 255 (in 8-bit or paletted images) or 65535 -(in 16-bit images) is fully opaque, with - - png_set_invert_alpha(png_ptr); - -This must appear before png_write_info() instead of later with the -other transformations because in the case of paletted images the tRNS -chunk data has to be inverted before the tRNS chunk is written. If -your image is not a paletted image, the tRNS data (which in such cases -represents a single color to be rendered as transparent) won't need to -be changed, and you can safely do this transformation after your -png_write_info() call. - -If you need to write a private chunk that you want to appear before -the PLTE chunk when PLTE is present, you can write the PNG info in -two steps, and insert code to write your own chunk between them: - - png_write_info_before_PLTE(png_ptr, info_ptr); - png_set_unknown_chunks(png_ptr, info_ptr, ...); - png_write_info(png_ptr, info_ptr); - -After you've written the file information, you can set up the library -to handle any special transformations of the image data. The various -ways to transform the data will be described in the order that they -should occur. This is important, as some of these change the color -type and/or bit depth of the data, and some others only work on -certain color types and bit depths. Even though each transformation -checks to see if it has data that it can do something with, you should -make sure to only enable a transformation if it will be valid for the -data. For example, don't swap red and blue on grayscale data. - -PNG files store RGB pixels packed into 3 or 6 bytes. This code tells -the library to strip input data that has 4 or 8 bytes per pixel down -to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2 -bytes per pixel). - - png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); - -where the 0 is unused, and the location is either PNG_FILLER_BEFORE or -PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel -is stored XRGB or RGBX. - -PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as -they can, resulting in, for example, 8 pixels per byte for 1 bit files. -If the data is supplied at 1 pixel per byte, use this code, which will -correctly pack the pixels into a single byte: - - png_set_packing(png_ptr); - -PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your -data is of another bit depth, you can write an sBIT chunk into the -file so that decoders can recover the original data if desired. - - /* Set the true bit depth of the image data */ - if (color_type & PNG_COLOR_MASK_COLOR) - { - sig_bit.red = true_bit_depth; - sig_bit.green = true_bit_depth; - sig_bit.blue = true_bit_depth; - } - else - { - sig_bit.gray = true_bit_depth; - } - if (color_type & PNG_COLOR_MASK_ALPHA) - { - sig_bit.alpha = true_bit_depth; - } - - png_set_sBIT(png_ptr, info_ptr, &sig_bit); - -If the data is stored in the row buffer in a bit depth other than -one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG), -this will scale the values to appear to be the correct bit depth as -is required by PNG. - - png_set_shift(png_ptr, &sig_bit); - -PNG files store 16 bit pixels in network byte order (big-endian, -ie. most significant bits first). This code would be used if they are -supplied the other way (little-endian, i.e. least significant bits -first, the way PCs store them): - - if (bit_depth > 8) - png_set_swap(png_ptr); - -If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you -need to change the order the pixels are packed into bytes, you can use: - - if (bit_depth < 8) - png_set_packswap(png_ptr); - -PNG files store 3 color pixels in red, green, blue order. This code -would be used if they are supplied as blue, green, red: - - png_set_bgr(png_ptr); - -PNG files describe monochrome as black being zero and white being -one. This code would be used if the pixels are supplied with this reversed -(black being one and white being zero): - - png_set_invert_mono(png_ptr); - -Finally, you can write your own transformation function if none of -the existing ones meets your needs. This is done by setting a callback -with - - png_set_write_user_transform_fn(png_ptr, - write_transform_fn); - -You must supply the function - - void write_transform_fn(png_ptr ptr, row_info_ptr - row_info, png_bytep data) - -See pngtest.c for a working example. Your function will be called -before any of the other transformations are processed. - -You can also set up a pointer to a user structure for use by your -callback function. - - png_set_user_transform_info(png_ptr, user_ptr, 0, 0); - -The user_channels and user_depth parameters of this function are ignored -when writing; you can set them to zero as shown. - -You can retrieve the pointer via the function png_get_user_transform_ptr(). -For example: - - voidp write_user_transform_ptr = - png_get_user_transform_ptr(png_ptr); - -It is possible to have libpng flush any pending output, either manually, -or automatically after a certain number of lines have been written. To -flush the output stream a single time call: - - png_write_flush(png_ptr); - -and to have libpng flush the output stream periodically after a certain -number of scanlines have been written, call: - - png_set_flush(png_ptr, nrows); - -Note that the distance between rows is from the last time png_write_flush() -was called, or the first row of the image if it has never been called. -So if you write 50 lines, and then png_set_flush 25, it will flush the -output on the next scanline, and every 25 lines thereafter, unless -png_write_flush() is called before 25 more lines have been written. -If nrows is too small (less than about 10 lines for a 640 pixel wide -RGB image) the image compression may decrease noticeably (although this -may be acceptable for real-time applications). Infrequent flushing will -only degrade the compression performance by a few percent over images -that do not use flushing. - -Writing the image data - -That's it for the transformations. Now you can write the image data. -The simplest way to do this is in one function call. If you have the -whole image in memory, you can just call png_write_image() and libpng -will write the image. You will need to pass in an array of pointers to -each row. This function automatically handles interlacing, so you don't -need to call png_set_interlace_handling() or call this function multiple -times, or any of that other stuff necessary with png_write_rows(). - - png_write_image(png_ptr, row_pointers); - -where row_pointers is: - - png_byte *row_pointers[height]; - -You can point to void or char or whatever you use for pixels. - -If you don't want to write the whole image at once, you can -use png_write_rows() instead. If the file is not interlaced, -this is simple: - - png_write_rows(png_ptr, row_pointers, - number_of_rows); - -row_pointers is the same as in the png_write_image() call. - -If you are just writing one row at a time, you can do this with -a single row_pointer instead of an array of row_pointers: - - png_bytep row_pointer = row; - - png_write_row(png_ptr, row_pointer); - -When the file is interlaced, things can get a good deal more complicated. -The only currently (as of the PNG Specification version 1.2, dated July -1999) defined interlacing scheme for PNG files is the "Adam7" interlace -scheme, that breaks down an image into seven smaller images of varying -size. libpng will build these images for you, or you can do them -yourself. If you want to build them yourself, see the PNG specification -for details of which pixels to write when. - -If you don't want libpng to handle the interlacing details, just -use png_set_interlace_handling() and call png_write_rows() the -correct number of times to write all seven sub-images. - -If you want libpng to build the sub-images, call this before you start -writing any rows: - - number_of_passes = - png_set_interlace_handling(png_ptr); - -This will return the number of passes needed. Currently, this is seven, -but may change if another interlace type is added. - -Then write the complete image number_of_passes times. - - png_write_rows(png_ptr, row_pointers, - number_of_rows); - -As some of these rows are not used, and thus return immediately, you may -want to read about interlacing in the PNG specification, and only update -the rows that are actually used. - -Finishing a sequential write - -After you are finished writing the image, you should finish writing -the file. If you are interested in writing comments or time, you should -pass an appropriately filled png_info pointer. If you are not interested, -you can pass NULL. - - png_write_end(png_ptr, info_ptr); - -When you are done, you can free all memory used by libpng like this: - - png_destroy_write_struct(&png_ptr, &info_ptr); - -It is also possible to individually free the info_ptr members that -point to libpng-allocated storage with the following function: - - png_free_data(png_ptr, info_ptr, mask, seq) - mask - identifies data to be freed, a mask - containing the bitwise OR of one or - more of - PNG_FREE_PLTE, PNG_FREE_TRNS, - PNG_FREE_HIST, PNG_FREE_ICCP, - PNG_FREE_PCAL, PNG_FREE_ROWS, - PNG_FREE_SCAL, PNG_FREE_SPLT, - PNG_FREE_TEXT, PNG_FREE_UNKN, - or simply PNG_FREE_ALL - seq - sequence number of item to be freed - (-1 for all items) - -This function may be safely called when the relevant storage has -already been freed, or has not yet been allocated, or was allocated -by the user and not by libpng, and will in those cases do nothing. -The "seq" parameter is ignored if only one item of the selected data -type, such as PLTE, is allowed. If "seq" is not -1, and multiple items -are allowed for the data type identified in the mask, such as text or -sPLT, only the n'th item in the structure is freed, where n is "seq". - -If you allocated data such as a palette that you passed in to libpng -with png_set_*, you must not free it until just before the call to -png_destroy_write_struct(). - -The default behavior is only to free data that was allocated internally -by libpng. This can be changed, so that libpng will not free the data, -or so that it will free data that was allocated by the user with png_malloc() -or png_zalloc() and passed in via a png_set_*() function, with - - png_data_freer(png_ptr, info_ptr, freer, mask) - mask - which data elements are affected - same choices as in png_free_data() - freer - one of - PNG_DESTROY_WILL_FREE_DATA - PNG_SET_WILL_FREE_DATA - PNG_USER_WILL_FREE_DATA - -For example, to transfer responsibility for some data from a read structure -to a write structure, you could use - - png_data_freer(read_ptr, read_info_ptr, - PNG_USER_WILL_FREE_DATA, - PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) - png_data_freer(write_ptr, write_info_ptr, - PNG_DESTROY_WILL_FREE_DATA, - PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) - -thereby briefly reassigning responsibility for freeing to the user but -immediately afterwards reassigning it once more to the write_destroy -function. Having done this, it would then be safe to destroy the read -structure and continue to use the PLTE, tRNS, and hIST data in the write -structure. - -This function only affects data that has already been allocated. -You can call this function before calling after the png_set_*() functions -to control whether the user or png_destroy_*() is supposed to free the data. -When the user assumes responsibility for libpng-allocated data, the -application must use -png_free() to free it, and when the user transfers responsibility to libpng -for data that the user has allocated, the user must have used png_malloc() -or png_zalloc() to allocate it. - -If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword -separately, do not transfer responsibility for freeing text_ptr to libpng, -because when libpng fills a png_text structure it combines these members with -the key member, and png_free_data() will free only text_ptr.key. Similarly, -if you transfer responsibility for free'ing text_ptr from libpng to your -application, your application must not separately free those members. -For a more compact example of writing a PNG image, see the file example.c. - -V. Modifying/Customizing libpng: - -There are two issues here. The first is changing how libpng does -standard things like memory allocation, input/output, and error handling. -The second deals with more complicated things like adding new chunks, -adding new transformations, and generally changing how libpng works. -Both of those are compile-time issues; that is, they are generally -determined at the time the code is written, and there is rarely a need -to provide the user with a means of changing them. - -Memory allocation, input/output, and error handling - -All of the memory allocation, input/output, and error handling in libpng -goes through callbacks that are user-settable. The default routines are -in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change -these functions, call the appropriate png_set_*_fn() function. - -Memory allocation is done through the functions png_malloc(), png_calloc(), -and png_free(). These currently just call the standard C functions. -png_calloc() calls png_malloc() and then png_memset() to clear the newly -allocated memory to zero. If your pointers can't access more then 64K -at a time, you will want to set MAXSEG_64K in zlib.h. Since it is -unlikely that the method of handling memory allocation on a platform -will change between applications, these functions must be modified in -the library at compile time. If you prefer to use a different method -of allocating and freeing data, you can use png_create_read_struct_2() or -png_create_write_struct_2() to register your own functions as described -above. These functions also provide a void pointer that can be retrieved -via - - mem_ptr=png_get_mem_ptr(png_ptr); - -Your replacement memory functions must have prototypes as follows: - - png_voidp malloc_fn(png_structp png_ptr, - png_alloc_size_t size); - void free_fn(png_structp png_ptr, png_voidp ptr); - -Your malloc_fn() must return NULL in case of failure. The png_malloc() -function will normally call png_error() if it receives a NULL from the -system memory allocator or from your replacement malloc_fn(). - -Your free_fn() will never be called with a NULL ptr, since libpng's -png_free() checks for NULL before calling free_fn(). - -Input/Output in libpng is done through png_read() and png_write(), -which currently just call fread() and fwrite(). The FILE * is stored in -png_struct and is initialized via png_init_io(). If you wish to change -the method of I/O, the library supplies callbacks that you can set -through the function png_set_read_fn() and png_set_write_fn() at run -time, instead of calling the png_init_io() function. These functions -also provide a void pointer that can be retrieved via the function -png_get_io_ptr(). For example: - - png_set_read_fn(png_structp read_ptr, - voidp read_io_ptr, png_rw_ptr read_data_fn) - - png_set_write_fn(png_structp write_ptr, - voidp write_io_ptr, png_rw_ptr write_data_fn, - png_flush_ptr output_flush_fn); - - voidp read_io_ptr = png_get_io_ptr(read_ptr); - voidp write_io_ptr = png_get_io_ptr(write_ptr); - -The replacement I/O functions must have prototypes as follows: - - void user_read_data(png_structp png_ptr, - png_bytep data, png_size_t length); - void user_write_data(png_structp png_ptr, - png_bytep data, png_size_t length); - void user_flush_data(png_structp png_ptr); - -The user_read_data() function is responsible for detecting and -handling end-of-data errors. - -Supplying NULL for the read, write, or flush functions sets them back -to using the default C stream functions, which expect the io_ptr to -point to a standard *FILE structure. It is probably a mistake -to use NULL for one of write_data_fn and output_flush_fn but not both -of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined. -It is an error to read from a write stream, and vice versa. - -Error handling in libpng is done through png_error() and png_warning(). -Errors handled through png_error() are fatal, meaning that png_error() -should never return to its caller. Currently, this is handled via -setjmp() and longjmp() (unless you have compiled libpng with -PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()), -but you could change this to do things like exit() if you should wish, -as long as your function does not return. - -On non-fatal errors, png_warning() is called -to print a warning message, and then control returns to the calling code. -By default png_error() and png_warning() print a message on stderr via -fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined -(because you don't want the messages) or PNG_NO_STDIO defined (because -fprintf() isn't available). If you wish to change the behavior of the error -functions, you will need to set up your own message callbacks. These -functions are normally supplied at the time that the png_struct is created. -It is also possible to redirect errors and warnings to your own replacement -functions after png_create_*_struct() has been called by calling: - - png_set_error_fn(png_structp png_ptr, - png_voidp error_ptr, png_error_ptr error_fn, - png_error_ptr warning_fn); - - png_voidp error_ptr = png_get_error_ptr(png_ptr); - -If NULL is supplied for either error_fn or warning_fn, then the libpng -default function will be used, calling fprintf() and/or longjmp() if a -problem is encountered. The replacement error functions should have -parameters as follows: - - void user_error_fn(png_structp png_ptr, - png_const_charp error_msg); - void user_warning_fn(png_structp png_ptr, - png_const_charp warning_msg); - -The motivation behind using setjmp() and longjmp() is the C++ throw and -catch exception handling methods. This makes the code much easier to write, -as there is no need to check every return code of every function call. -However, there are some uncertainties about the status of local variables -after a longjmp, so the user may want to be careful about doing anything -after setjmp returns non-zero besides returning itself. Consult your -compiler documentation for more details. For an alternative approach, you -may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net). - -Custom chunks - -If you need to read or write custom chunks, you may need to get deeper -into the libpng code. The library now has mechanisms for storing -and writing chunks of unknown type; you can even declare callbacks -for custom chunks. However, this may not be good enough if the -library code itself needs to know about interactions between your -chunk and existing `intrinsic' chunks. - -If you need to write a new intrinsic chunk, first read the PNG -specification. Acquire a first level of understanding of how it works. -Pay particular attention to the sections that describe chunk names, -and look at how other chunks were designed, so you can do things -similarly. Second, check out the sections of libpng that read and -write chunks. Try to find a chunk that is similar to yours and use -it as a template. More details can be found in the comments inside -the code. It is best to handle unknown chunks in a generic method, -via callback functions, instead of by modifying libpng functions. - -If you wish to write your own transformation for the data, look through -the part of the code that does the transformations, and check out some of -the simpler ones to get an idea of how they work. Try to find a similar -transformation to the one you want to add and copy off of it. More details -can be found in the comments inside the code itself. - -Configuring for 16 bit platforms - -You will want to look into zconf.h to tell zlib (and thus libpng) that -it cannot allocate more then 64K at a time. Even if you can, the memory -won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K. - -Configuring for DOS - -For DOS users who only have access to the lower 640K, you will -have to limit zlib's memory usage via a png_set_compression_mem_level() -call. See zlib.h or zconf.h in the zlib library for more information. - -Configuring for Medium Model - -Libpng's support for medium model has been tested on most of the popular -compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets -defined, and FAR gets defined to far in pngconf.h, and you should be -all set. Everything in the library (except for zlib's structure) is -expecting far data. You must use the typedefs with the p or pp on -the end for pointers (or at least look at them and be careful). Make -note that the rows of data are defined as png_bytepp, which is an -unsigned char far * far *. - -Configuring for gui/windowing platforms: - -You will need to write new error and warning functions that use the GUI -interface, as described previously, and set them to be the error and -warning functions at the time that png_create_*_struct() is called, -in order to have them available during the structure initialization. -They can be changed later via png_set_error_fn(). On some compilers, -you may also have to change the memory allocators (png_malloc, etc.). - -Configuring for compiler xxx: - -All includes for libpng are in pngconf.h. If you need to add, change -or delete an include, this is the place to do it. -The includes that are not needed outside libpng are placed in pngpriv.h, -which is only used by the routines inside libpng itself. -The files in libpng proper only include pngpriv.h and png.h, which -in turn includes pngconf.h. - -Configuring zlib: - -There are special functions to configure the compression. Perhaps the -most useful one changes the compression level, which currently uses -input compression values in the range 0 - 9. The library normally -uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests -have shown that for a large majority of images, compression values in -the range 3-6 compress nearly as well as higher levels, and do so much -faster. For online applications it may be desirable to have maximum speed -(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also -specify no compression (Z_NO_COMPRESSION = 0), but this would create -files larger than just storing the raw bitmap. You can specify the -compression level by calling: - - png_set_compression_level(png_ptr, level); - -Another useful one is to reduce the memory level used by the library. -The memory level defaults to 8, but it can be lowered if you are -short on memory (running DOS, for example, where you only have 640K). -Note that the memory level does have an effect on compression; among -other things, lower levels will result in sections of incompressible -data being emitted in smaller stored blocks, with a correspondingly -larger relative overhead of up to 15% in the worst case. - - png_set_compression_mem_level(png_ptr, level); - -The other functions are for configuring zlib. They are not recommended -for normal use and may result in writing an invalid PNG file. See -zlib.h for more information on what these mean. - - png_set_compression_strategy(png_ptr, - strategy); - png_set_compression_window_bits(png_ptr, - window_bits); - png_set_compression_method(png_ptr, method); - png_set_compression_buffer_size(png_ptr, size); - -Controlling row filtering - -If you want to control whether libpng uses filtering or not, which -filters are used, and how it goes about picking row filters, you -can call one of these functions. The selection and configuration -of row filters can have a significant impact on the size and -encoding speed and a somewhat lesser impact on the decoding speed -of an image. Filtering is enabled by default for RGB and grayscale -images (with and without alpha), but not for paletted images nor -for any images with bit depths less than 8 bits/pixel. - -The 'method' parameter sets the main filtering method, which is -currently only '0' in the PNG 1.2 specification. The 'filters' -parameter sets which filter(s), if any, should be used for each -scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS -to turn filtering on and off, respectively. - -Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB, -PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise -ORed together with '|' to specify one or more filters to use. -These filters are described in more detail in the PNG specification. -If you intend to change the filter type during the course of writing -the image, you should start with flags set for all of the filters -you intend to use so that libpng can initialize its internal -structures appropriately for all of the filter types. (Note that this -means the first row must always be adaptively filtered, because libpng -currently does not allocate the filter buffers until png_write_row() -is called for the first time.) - - filters = PNG_FILTER_NONE | PNG_FILTER_SUB - PNG_FILTER_UP | PNG_FILTER_AVG | - PNG_FILTER_PAETH | PNG_ALL_FILTERS; - - png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, - filters); - The second parameter can also be - PNG_INTRAPIXEL_DIFFERENCING if you are - writing a PNG to be embedded in a MNG - datastream. This parameter must be the - same as the value of filter_method used - in png_set_IHDR(). - -It is also possible to influence how libpng chooses from among the -available filters. This is done in one or both of two ways - by -telling it how important it is to keep the same filter for successive -rows, and by telling it the relative computational costs of the filters. - - double weights[3] = {1.5, 1.3, 1.1}, - costs[PNG_FILTER_VALUE_LAST] = - {1.0, 1.3, 1.3, 1.5, 1.7}; - - png_set_filter_heuristics(png_ptr, - PNG_FILTER_HEURISTIC_WEIGHTED, 3, - weights, costs); - -The weights are multiplying factors that indicate to libpng that the -row filter should be the same for successive rows unless another row filter -is that many times better than the previous filter. In the above example, -if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a -"sum of absolute differences" 1.5 x 1.3 times higher than other filters -and still be chosen, while the NONE filter could have a sum 1.1 times -higher than other filters and still be chosen. Unspecified weights are -taken to be 1.0, and the specified weights should probably be declining -like those above in order to emphasize recent filters over older filters. - -The filter costs specify for each filter type a relative decoding cost -to be considered when selecting row filters. This means that filters -with higher costs are less likely to be chosen over filters with lower -costs, unless their "sum of absolute differences" is that much smaller. -The costs do not necessarily reflect the exact computational speeds of -the various filters, since this would unduly influence the final image -size. - -Note that the numbers above were invented purely for this example and -are given only to help explain the function usage. Little testing has -been done to find optimum values for either the costs or the weights. - -Removing unwanted object code - -There are a bunch of #define's in pngconf.h that control what parts of -libpng are compiled. All the defines end in _SUPPORTED. If you are -never going to use a capability, you can change the #define to #undef -before recompiling libpng and save yourself code and data space, or -you can turn off individual capabilities with defines that begin with -PNG_NO_. - -You can also turn all of the transforms and ancillary chunk capabilities -off en masse with compiler directives that define -PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS, -or all four, -along with directives to turn on any of the capabilities that you do -want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra -transformations but still leave the library fully capable of reading -and writing PNG files with all known public chunks. Use of the -PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library -that is incapable of reading or writing ancillary chunks. If you are -not using the progressive reading capability, you can turn that off -with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING -capability, which you'll still have). - -All the reading and writing specific code are in separate files, so the -linker should only grab the files it needs. However, if you want to -make sure, or if you are building a stand alone library, all the -reading files start with pngr and all the writing files start with -pngw. The files that don't match either (like png.c, pngtrans.c, etc.) -are used for both reading and writing, and always need to be included. -The progressive reader is in pngpread.c - -If you are creating or distributing a dynamically linked library (a .so -or DLL file), you should not remove or disable any parts of the library, -as this will cause applications linked with different versions of the -library to fail if they call functions not available in your library. -The size of the library itself should not be an issue, because only -those sections that are actually used will be loaded into memory. - -Requesting debug printout - -The macro definition PNG_DEBUG can be used to request debugging -printout. Set it to an integer value in the range 0 to 3. Higher -numbers result in increasing amounts of debugging information. The -information is printed to the "stderr" file, unless another file -name is specified in the PNG_DEBUG_FILE macro definition. - -When PNG_DEBUG > 0, the following functions (macros) become available: - - png_debug(level, message) - png_debug1(level, message, p1) - png_debug2(level, message, p1, p2) - -in which "level" is compared to PNG_DEBUG to decide whether to print -the message, "message" is the formatted string to be printed, -and p1 and p2 are parameters that are to be embedded in the string -according to printf-style formatting directives. For example, - - png_debug1(2, "foo=%d\n", foo); - -is expanded to - - if(PNG_DEBUG > 2) - fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo); - -When PNG_DEBUG is defined but is zero, the macros aren't defined, but you -can still use PNG_DEBUG to control your own debugging: - - #ifdef PNG_DEBUG - fprintf(stderr, ... - #endif - -When PNG_DEBUG = 1, the macros are defined, but only png_debug statements -having level = 0 will be printed. There aren't any such statements in -this version of libpng, but if you insert some they will be printed. - -VI. MNG support - -The MNG specification (available at http://www.libpng.org/pub/mng) allows -certain extensions to PNG for PNG images that are embedded in MNG datastreams. -Libpng can support some of these extensions. To enable them, use the -png_permit_mng_features() function: - - feature_set = png_permit_mng_features(png_ptr, mask) - mask is a png_uint_32 containing the bitwise OR of the - features you want to enable. These include - PNG_FLAG_MNG_EMPTY_PLTE - PNG_FLAG_MNG_FILTER_64 - PNG_ALL_MNG_FEATURES - feature_set is a png_uint_32 that is the bitwise AND of - your mask with the set of MNG features that is - supported by the version of libpng that you are using. - -It is an error to use this function when reading or writing a standalone -PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped -in a MNG datastream. As a minimum, it must have the MNG 8-byte signature -and the MHDR and MEND chunks. Libpng does not provide support for these -or any other MNG chunks; your application must provide its own support for -them. You may wish to consider using libmng (available at -http://www.libmng.com) instead. - -VII. Changes to Libpng from version 0.88 - -It should be noted that versions of libpng later than 0.96 are not -distributed by the original libpng author, Guy Schalnat, nor by -Andreas Dilger, who had taken over from Guy during 1996 and 1997, and -distributed versions 0.89 through 0.96, but rather by another member -of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are -still alive and well, but they have moved on to other things. - -The old libpng functions png_read_init(), png_write_init(), -png_info_init(), png_read_destroy(), and png_write_destroy() have been -moved to PNG_INTERNAL in version 0.95 to discourage their use. These -functions will be removed from libpng version 2.0.0. - -The preferred method of creating and initializing the libpng structures is -via the png_create_read_struct(), png_create_write_struct(), and -png_create_info_struct() because they isolate the size of the structures -from the application, allow version error checking, and also allow the -use of custom error handling routines during the initialization, which -the old functions do not. The functions png_read_destroy() and -png_write_destroy() do not actually free the memory that libpng -allocated for these structs, but just reset the data structures, so they -can be used instead of png_destroy_read_struct() and -png_destroy_write_struct() if you feel there is too much system overhead -allocating and freeing the png_struct for each image read. - -Setting the error callbacks via png_set_message_fn() before -png_read_init() as was suggested in libpng-0.88 is no longer supported -because this caused applications that do not use custom error functions -to fail if the png_ptr was not initialized to zero. It is still possible -to set the error callbacks AFTER png_read_init(), or to change them with -png_set_error_fn(), which is essentially the same function, but with a new -name to force compilation errors with applications that try to use the old -method. - -Starting with version 1.0.7, you can find out which version of the library -you are using at run-time: - - png_uint_32 libpng_vn = png_access_version_number(); - -The number libpng_vn is constructed from the major version, minor -version with leading zero, and release number with leading zero, -(e.g., libpng_vn for version 1.0.7 is 10007). - -You can also check which version of png.h you used when compiling your -application: - - png_uint_32 application_vn = PNG_LIBPNG_VER; - -VIII. Changes to Libpng from version 1.0.x to 1.2.x - -Support for user memory management was enabled by default. To -accomplish this, the functions png_create_read_struct_2(), -png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(), -png_malloc_default(), and png_free_default() were added. - -Support for the iTXt chunk has been enabled by default as of -version 1.2.41. - -Support for certain MNG features was enabled. - -Support for numbered error messages was added. However, we never got -around to actually numbering the error messages. The function -png_set_strip_error_numbers() was added (Note: the prototype for this -function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE -builds of libpng-1.2.15. It was restored in libpng-1.2.36). - -The png_malloc_warn() function was added at libpng-1.2.3. This issues -a png_warning and returns NULL instead of aborting when it fails to -acquire the requested memory allocation. - -Support for setting user limits on image width and height was enabled -by default. The functions png_set_user_limits(), png_get_user_width_max(), -and png_get_user_height_max() were added at libpng-1.2.6. - -The png_set_add_alpha() function was added at libpng-1.2.7. - -The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9. -Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the -tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is -deprecated. - -A number of macro definitions in support of runtime selection of -assembler code features (especially Intel MMX code support) were -added at libpng-1.2.0: - - PNG_ASM_FLAG_MMX_SUPPORT_COMPILED - PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU - PNG_ASM_FLAG_MMX_READ_COMBINE_ROW - PNG_ASM_FLAG_MMX_READ_INTERLACE - PNG_ASM_FLAG_MMX_READ_FILTER_SUB - PNG_ASM_FLAG_MMX_READ_FILTER_UP - PNG_ASM_FLAG_MMX_READ_FILTER_AVG - PNG_ASM_FLAG_MMX_READ_FILTER_PAETH - PNG_ASM_FLAGS_INITIALIZED - PNG_MMX_READ_FLAGS - PNG_MMX_FLAGS - PNG_MMX_WRITE_FLAGS - PNG_MMX_FLAGS - -We added the following functions in support of runtime -selection of assembler code features: - - png_get_mmx_flagmask() - png_set_mmx_thresholds() - png_get_asm_flags() - png_get_mmx_bitdepth_threshold() - png_get_mmx_rowbytes_threshold() - png_set_asm_flags() - -We replaced all of these functions with simple stubs in libpng-1.2.20, -when the Intel assembler code was removed due to a licensing issue. - -These macros are deprecated: - - PNG_READ_TRANSFORMS_NOT_SUPPORTED - PNG_PROGRESSIVE_READ_NOT_SUPPORTED - PNG_NO_SEQUENTIAL_READ_SUPPORTED - PNG_WRITE_TRANSFORMS_NOT_SUPPORTED - PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED - PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED - -They have been replaced, respectively, by: - - PNG_NO_READ_TRANSFORMS - PNG_NO_PROGRESSIVE_READ - PNG_NO_SEQUENTIAL_READ - PNG_NO_WRITE_TRANSFORMS - PNG_NO_READ_ANCILLARY_CHUNKS - PNG_NO_WRITE_ANCILLARY_CHUNKS - -PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been -deprecated since libpng-1.0.16 and libpng-1.2.6. - -The function - png_check_sig(sig, num) -was replaced with - !png_sig_cmp(sig, 0, num) -It has been deprecated since libpng-0.90. - -The function - png_set_gray_1_2_4_to_8() -which also expands tRNS to alpha was replaced with - png_set_expand_gray_1_2_4_to_8() -which does not. It has been deprecated since libpng-1.0.18 and 1.2.9. - -IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x - -Private libpng prototypes and macro definitions were moved from -png.h and pngconf.h into a new pngpriv.h header file. - -Functions png_set_benign_errors(), png_benign_error(), and -png_chunk_benign_error() were added. - -Support for setting the maximum amount of memory that the application -will allocate for reading chunks was added, as a security measure. -The functions png_set_chunk_cache_max() and png_get_chunk_cache_max() -were added to the library. - -We implemented support for I/O states by adding png_ptr member io_state -and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c - -We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level -input transforms. - -Checking for and reporting of errors in the IHDR chunk is more thorough. - -Support for global arrays was removed, to improve thread safety. - -Some obsolete/deprecated macros and functions have been removed. - -Typecasted NULL definitions such as - #define png_voidp_NULL (png_voidp)NULL -were eliminated. If you used these in your application, just use -NULL instead. - -The png_struct and info_struct members "trans" and "trans_values" were -changed to "trans_alpha" and "trans_color", respectively. - -The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles -were removed. - -The PNG_1_0_X and PNG_1_2_X macros were eliminated. - -The PNG_LEGACY_SUPPORTED macro was eliminated. - -Many WIN32_WCE #ifdefs were removed. - -The functions png_read_init(info_ptr), png_write_init(info_ptr), -png_info_init(info_ptr), png_read_destroy(), and png_write_destroy() -have been removed. They have been deprecated since libpng-0.95. - -The png_permit_empty_plte() was removed. It has been deprecated -since libpng-1.0.9. Use png_permit_mng_features() instead. - -We removed the obsolete stub functions png_get_mmx_flagmask(), -png_set_mmx_thresholds(), png_get_asm_flags(), -png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(), -png_set_asm_flags(), and png_mmx_supported() - -We removed the obsolete png_check_sig(), png_memcpy_check(), and -png_memset_check() functions. Instead use !png_sig_cmp(), png_memcpy(), -and png_memset(), respectively. - -The function png_set_gray_1_2_4_to_8() was removed. It has been -deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with -png_set_expand_gray_1_2_4_to_8() because the former function also -expanded palette images. - -We changed the prototype for png_malloc() from - png_malloc(png_structp png_ptr, png_uint_32 size) -to - png_malloc(png_structp png_ptr, png_alloc_size_t size) - -This also applies to the prototype for the user replacement malloc_fn(). - -The png_calloc() function was added and is used in place of -of "png_malloc(); png_memset();" except in the case in png_read_png() -where the array consists of pointers; in this case a "for" loop is used -after the png_malloc() to set the pointers to NULL, to give robust. -behavior in case the application runs out of memory part-way through -the process. - -We changed the prototypes of png_get_compression_buffer_size() and -png_set_compression_buffer_size() to work with png_size_t instead of -png_uint_32. - -Support for numbered error messages was removed by default, since we -never got around to actually numbering the error messages. The function -png_set_strip_error_numbers() was removed from the library by default. - -The png_zalloc() and png_zfree() functions are no longer exported. -The png_zalloc() function no longer zeroes out the memory that it -allocates. - -Support for dithering was disabled by default in libpng-1.4.0, because -been well tested and doesn't actually "dither". The code was not -removed, however, and could be enabled by building libpng with -PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support -was reenabled, but the function was renamed png_set_quantize() to -reflect more accurately what it actually does. At the same time, -the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to -PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS. - -We removed the trailing '.' from the warning and error messages. - -X. Detecting libpng - -The png_get_io_ptr() function has been present since libpng-0.88, has never -changed, and is unaffected by conditional compilation macros. It is the -best choice for use in configure scripts for detecting the presence of any -libpng version since 0.88. In an autoconf "configure.in" you could use - - AC_CHECK_LIB(png, png_get_io_ptr, ... - -XI. Source code repository - -Since about February 2009, version 1.2.34, libpng has been under "git" source -control. The git repository was built from old libpng-x.y.z.tar.gz files -going back to version 0.70. You can access the git repository (read only) -at - - git://libpng.git.sourceforge.net/gitroot/libpng - -or you can browse it via "gitweb" at - - http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng - -Patches can be sent to glennrp at users.sourceforge.net or to -png-mng-implement at lists.sourceforge.net or you can upload them to -the libpng bug tracker at - - http://libpng.sourceforge.net - -XII. Coding style - -Our coding style is similar to the "Allman" style, with curly -braces on separate lines: - - if (condition) - { - action; - } - - else if (another condition) - { - another action; - } - -The braces can be omitted from simple one-line actions: - - if (condition) - return (0); - -We use 3-space indentation, except for continued statements which -are usually indented the same as the first line of the statement -plus four more spaces. - -For macro definitions we use 2-space indentation, always leaving the "#" -in the first column. - - #ifndef PNG_NO_FEATURE - # ifndef PNG_FEATURE_SUPPORTED - # define PNG_FEATURE_SUPPORTED - # endif - #endif - -Comments appear with the leading "/*" at the same indentation as -the statement that follows the comment: - - /* Single-line comment */ - statement; - - /* This is a multiple-line - * comment. - */ - statement; - -Very short comments can be placed after the end of the statement -to which they pertain: - - statement; /* comment */ - -We don't use C++ style ("//") comments. We have, however, -used them in the past in some now-abandoned MMX assembler -code. - -Functions and their curly braces are not indented, and -exported functions are marked with PNGAPI: - - /* This is a public function that is visible to - * application programers. It does thus-and-so. - */ - void PNGAPI - png_exported_function(png_ptr, png_info, foo) - { - body; - } - -The prototypes for all exported functions appear in png.h, -above the comment that says - - /* Maintainer: Put new public prototypes here ... */ - -We mark all non-exported functions with "/* PRIVATE */"": - - void /* PRIVATE */ - png_non_exported_function(png_ptr, png_info, foo) - { - body; - } - -The prototypes for non-exported functions (except for those in -pngtest) appear in -pngpriv.h -above the comment that says - - /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */ - -The names of all exported functions and variables begin -with "png_", and all publicly visible C preprocessor -macros begin with "PNG_". - -We put a space after each comma and after each semicolon -in "for" statments, and we put spaces before and after each -C binary operator and after "for" or "while", and before -"?". We don't put a space between a typecast and the expression -being cast, nor do we put one between a function name and the -left parenthesis that follows it: - - for (i = 2; i > 0; --i) - y[i] = a(x) + (int)b; - -We prefer #ifdef and #ifndef to #if defined() and if !defined() -when there is only one macro being tested. - -We do not use the TAB character for indentation in the C sources. - -Lines do not exceed 80 characters. - -Other rules can be inferred by inspecting the libpng source. - -XIII. Y2K Compliance in libpng - -June 26, 2010 - -Since the PNG Development group is an ad-hoc body, we can't make -an official declaration. - -This is your unofficial assurance that libpng from version 0.71 and -upward through 1.4.3 are Y2K compliant. It is my belief that earlier -versions were also Y2K compliant. - -Libpng only has three year fields. One is a 2-byte unsigned integer that -will hold years up to 65535. The other two hold the date in text -format, and will hold years up to 9999. - -The integer is - "png_uint_16 year" in png_time_struct. - -The strings are - "png_charp time_buffer" in png_struct and - "near_time_buffer", which is a local character string in png.c. - -There are seven time-related functions: - - png_convert_to_rfc_1123() in png.c - (formerly png_convert_to_rfc_1152() in error) - png_convert_from_struct_tm() in pngwrite.c, called - in pngwrite.c - png_convert_from_time_t() in pngwrite.c - png_get_tIME() in pngget.c - png_handle_tIME() in pngrutil.c, called in pngread.c - png_set_tIME() in pngset.c - png_write_tIME() in pngwutil.c, called in pngwrite.c - -All appear to handle dates properly in a Y2K environment. The -png_convert_from_time_t() function calls gmtime() to convert from system -clock time, which returns (year - 1900), which we properly convert to -the full 4-digit year. There is a possibility that applications using -libpng are not passing 4-digit years into the png_convert_to_rfc_1123() -function, or that they are incorrectly passing only a 2-digit year -instead of "year - 1900" into the png_convert_from_struct_tm() function, -but this is not under our control. The libpng documentation has always -stated that it works with 4-digit years, and the APIs have been -documented as such. - -The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned -integer to hold the year, and can hold years as large as 65535. - -zlib, upon which libpng depends, is also Y2K compliant. It contains -no date-related code. - - - Glenn Randers-Pehrson - libpng maintainer - PNG Development Group Index: dll/3rdparty/libpng/docs/libpng-manual.txt =================================================================== --- dll/3rdparty/libpng/docs/libpng-manual.txt (revision 56925) +++ dll/3rdparty/libpng/docs/libpng-manual.txt (working copy) @@ -1,6 +1,6 @@ -libpng-manual.txt - A description on how to use and modify libpng +Libpng-manual.txt - A description on how to use and modify libpng - libpng version 1.5.2 - March 31, 2011 + libpng version 1.5.12 - July 11, 2012 Updated and distributed by Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson @@ -11,7 +11,7 @@ Based on: - libpng versions 0.97, January 1998, through 1.5.2 - March 31, 2011 + libpng versions 0.97, January 1998, through 1.5.12 - July 11, 2012 Updated and distributed by Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson @@ -107,7 +107,8 @@ directly accessible to the user. However, this tended to cause problems with applications using dynamically loaded libraries, and as a result a set of interface functions for png_info (the png_get_*() and png_set_*() -functions) was developed. +functions) was developed, and direct access to the png_info fields was +deprecated.. The png_struct structure is the object used by the library to decode a single image. As of 1.5.0 this structure is also not exposed. @@ -116,14 +117,23 @@ Many (in particular the png_set and png_get APIs) also require a pointer to png_info as the second argument. Some application visible macros defined in png.h designed for basic data access (reading and writing -integers in the PNG format) break this rule, but it's almost always safe -to assume that a (png_struct*) has to be passed to call an API function. +integers in the PNG format) don't take a png_info pointer, but it's almost +always safe to assume that a (png_struct*) has to be passed to call an API +function. +You can have more than one png_info structure associated with an image, +as illustrated in pngtest.c, one for information valid prior to the +IDAT chunks and another (called "end_info" below) for things after them. + The png.h header file is an invaluable reference for programming with libpng. And while I'm on the topic, make sure you include the libpng header file: #include +and also (as of libpng-1.5.0) the zlib header file, if you need it: + +#include + Types The png.h header file defines a number of integral types used by the @@ -131,15 +141,15 @@ to integers of particular sizes and types for passing color values. One exception is how non-integral numbers are handled. For application -convenience most APIs that take such numbers have C (double) arguments, -however internally PNG, and libpng, use 32 bit signed integers and encode +convenience most APIs that take such numbers have C (double) arguments; +however, internally PNG, and libpng, use 32 bit signed integers and encode the value by multiplying by 100,000. As of libpng 1.5.0 a convenience macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point) which is simply (png_int_32). -All APIs that take (double) arguments also have an matching API that +All APIs that take (double) arguments also have a matching API that takes the corresponding fixed point integer arguments. The fixed point -API has the same name as the floating point one with _fixed appended. +API has the same name as the floating point one with "_fixed" appended. The actual range of values permitted in the APIs is frequently less than the full range of (png_fixed_point) (-21474 to +21474). When APIs require a non-negative argument the type is recorded as png_uint_32 above. Consult @@ -157,6 +167,10 @@ #ifdef PNG_feature_SUPPORTED declare-function #endif + ... + #ifdef PNG_feature_SUPPORTED + use-function + #endif The library can be built without support for these APIs, although a standard build will have all implemented APIs. Application programs @@ -165,7 +179,7 @@ of libpng are recorded in the header file "pnglibconf.h" and this file is always included by png.h. -If you don't need to change the library configuration from the default skip to +If you don't need to change the library configuration from the default, skip to the next section ("Reading"). Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all @@ -197,24 +211,25 @@ reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand. -Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt and changing -the lines defining the supported features, paying very close attention to the -'option' information in scripts/pnglibconf.dfa that describes those features and -their requirements. This is easy to get wrong. +Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to +pnglibconf.h and changing the lines defining the supported features, paying +very close attention to the 'option' information in scripts/pnglibconf.dfa +that describes those features and their requirements. This is easy to get +wrong. B. Configuration using DFA_XTRA Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later variant such as 'nawk' or 'gawk', is available. The configure build will automatically find an appropriate awk and build pnglibconf.h. -scripts/pnglibconf.mak contains a set of make rules for doing the same thing if -configure is not used, and many of the makefiles in the scripts directory use -this approach. +The scripts/pnglibconf.mak file contains a set of make rules for doing the +same thing if configure is not used, and many of the makefiles in the scripts +directory use this approach. -When rebuilding simply write new file containing changed options and set +When rebuilding simply write a new file containing changed options and set DFA_XTRA to the name of this file. This causes the build to append the new file -to the end of scripts/pnglibconf.dfa. pngusr.dfa should contain lines of the -following forms: +to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines +of the following forms: everything = off @@ -238,12 +253,16 @@ but most of them have no visible effect on the API. Some can also be overridden from the API. +This method of building a customized pnglibconf.h is illustrated in +contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and +pngusr.dfa in these directories. + C. Configuration using PNG_USR_CONFIG If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file pngusr.h will automatically be included before the options in -scripts/pnglibconf.dfa are processed. pngusr.h should contain only macro -definitions turning features on or off or setting settings. +scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only +macro definitions turning features on or off or setting settings. Apart from the global setting "everything = off" all the options listed above can be set using macros in pngusr.h: @@ -274,6 +293,9 @@ dependency information for each setting and option. Simply locate the feature in the file and read the C comments that precede it. +This method is also illustrated in the contrib/pngminim/* makefiles and +pngusr.h. + III. Reading We'll now walk you through the possible functions to call when reading @@ -348,21 +370,12 @@ return (ERROR); } - png_infop end_info = png_create_info_struct(png_ptr); - - if (!end_info) - { - png_destroy_read_struct(&png_ptr, &info_ptr, - (png_infopp)NULL); - return (ERROR); - } - If you want to use your own memory allocation routines, use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use png_create_read_struct_2() instead of png_create_read_struct(): png_structp png_ptr = png_create_read_struct_2 - (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, + (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, user_error_fn, user_warning_fn, (png_voidp) user_mem_ptr, user_malloc_fn, user_free_fn); @@ -374,7 +387,7 @@ When libpng encounters an error, it expects to longjmp back to your routine. Therefore, you will need to call setjmp and pass your png_jmpbuf(png_ptr). If you read the file from different -routines, you will need to update the jmpbuf field every time you enter +routines, you will need to update the longjmp buffer every time you enter a new routine that will call a png_*() function. See your documentation of setjmp/longjmp for your compiler for more @@ -392,6 +405,9 @@ return (ERROR); } +Pass (png_infopp)NULL instead of &end_info if you didn't create +an end_info structure. + If you would rather avoid the complexity of setjmp/longjmp issues, you can compile libpng with PNG_NO_SETJMP, in which case errors will result in a call to PNG_ABORT() which defaults to abort(). @@ -563,6 +579,8 @@ instances of png_set_keep_unknown_chunks(), the final instance will take precedence. The IHDR and IEND chunks should not be named in chunk_list; if they are, libpng will process them normally anyway. +If you know that your application will never make use of some particular +chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below. Here is an example of the usage of png_set_keep_unknown_chunks(), where the private "vpAg" chunk will later be processed by a user chunk @@ -603,7 +621,7 @@ Since very few applications really need to process such large images, we have imposed an arbitrary 1-million limit on rows and columns. Larger images will be rejected immediately with a png_error() call. If -you wish to override this limit, you can use +you wish to change this limit, you can use png_set_user_limits(png_ptr, width_max, height_max); @@ -613,6 +631,10 @@ You should put this statement after you create the PNG structure and before calling png_read_info(), png_read_png(), or png_process_data(). + +When writing a PNG datastream, put this statement before calling +png_write_info() or png_write_png(). + If you need to retrieve the limits that are being applied, use width_max = png_get_user_width_max(png_ptr); @@ -643,6 +665,242 @@ Any chunks that would cause either of these limits to be exceeded will be ignored. +Information about your system + +If you intend to display the PNG or to incorporate it in other image data you +need to tell libpng information about your display or drawing surface so that +libpng can convert the values in the image to match the display. + +From libpng-1.5.4 this information can be set before reading the PNG file +header. In earlier versions png_set_gamma() existed but behaved incorrectly if +called before the PNG file header had been read and png_set_alpha_mode() did not +exist. + +If you need to support versions prior to libpng-1.5.4 test the version number +as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures +described in the appropriate manual page. + +You give libpng the encoding expected by your system expressed as a 'gamma' +value. You can also specify a default encoding for the PNG file in +case the required information is missing from the file. By default libpng +assumes that the PNG data matches your system, to keep this default call: + + png_set_gamma(png_ptr, screen_gamma, 1/screen_gamma/*file gamma*/); + +or you can use the fixed point equivalent: + + png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma, PNG_FP_1/screen_gamma); + +If you don't know the gamma for your system it is probably 2.2 - a good +approximation to the IEC standard for display systems (sRGB). If images are +too contrasty or washed out you got the value wrong - check your system +documentation! + +Many systems permit the system gamma to be changed via a lookup table in the +display driver, a few systems, including older Macs, change the response by +default. As of 1.5.4 three special values are available to handle common +situations: + + PNG_DEFAULT_sRGB: Indicates that the system conforms to the IEC 61966-2-1 + standard. This matches almost all systems. + PNG_GAMMA_MAC_18: Indicates that the system is an older (pre Mac OS 10.6) + Apple Macintosh system with the default settings. + PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates that the + system expects data with no gamma encoding. + +You would use the linear (unencoded) value if you need to process the pixel +values further because this avoids the need to decode and reencode each +component value whenever arithmetic is performed. A lot of graphics software +uses linear values for this reason, often with higher precision component values +to preserve overall accuracy. + +The second thing you may need to tell libpng about is how your system handles +alpha channel information. Some, but not all, PNG files contain an alpha +channel. To display these files correctly you need to compose the data onto a +suitable background, as described in the PNG specification. + +Libpng only supports composing onto a single color (using png_set_background; +see below). Otherwise you must do the composition yourself and, in this case, +you may need to call png_set_alpha_mode: + +#if PNG_LIBPNG_VER >= 10504 + png_set_alpha_mode(png_ptr, mode, screen_gamma); +#else + png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma); +#endif + +The screen_gamma value is the same as the argument to png_set_gamma; however, +how it affects the output depends on the mode. png_set_alpha_mode() sets the +file gamma default to 1/screen_gamma, so normally you don't need to call +png_set_gamma. If you need different defaults call png_set_gamma() before +png_set_alpha_mode() - if you call it after it will override the settings made +by png_set_alpha_mode(). + +The mode is as follows: + + PNG_ALPHA_PNG: The data is encoded according to the PNG specification. Red, +green and blue, or gray, components are gamma encoded color +values and are not premultiplied by the alpha value. The +alpha value is a linear measure of the contribution of the +pixel to the corresponding final output pixel. + +You should normally use this format if you intend to perform +color correction on the color values; most, maybe all, color +correction software has no handling for the alpha channel and, +anyway, the math to handle pre-multiplied component values is +unnecessarily complex. + +Before you do any arithmetic on the component values you need +to remove the gamma encoding and multiply out the alpha +channel. See the PNG specification for more detail. It is +important to note that when an image with an alpha channel is +scaled, linear encoded, pre-multiplied component values must +be used! + +The remaining modes assume you don't need to do any further color correction or +that if you do, your color correction software knows all about alpha (it +probably doesn't!) + + PNG_ALPHA_STANDARD: The data libpng produces +is encoded in the standard way +assumed by most correctly written graphics software. +The gamma encoding will be removed by libpng and the +linear component values will be pre-multiplied by the +alpha channel. + +With this format the final image must be re-encoded to +match the display gamma before the image is displayed. +If your system doesn't do that, yet still seems to +perform arithmetic on the pixels without decoding them, +it is broken - check out the modes below. + +With PNG_ALPHA_STANDARD libpng always produces linear +component values, whatever screen_gamma you supply. The +screen_gamma value is, however, used as a default for +the file gamma if the PNG file has no gamma information. + +If you call png_set_gamma() after png_set_alpha_mode() you +will override the linear encoding. Instead the +pre-multiplied pixel values will be gamma encoded but +the alpha channel will still be linear. This may +actually match the requirements of some broken software, +but it is unlikely. + +While linear 8-bit data is often used it has +insufficient precision for any image with a reasonable +dynamic range. To avoid problems, and if your software +supports it, use png_set_expand_16() to force all +components to 16 bits. + + PNG_ALPHA_OPTIMIZED: This mode is the same +as PNG_ALPHA_STANDARD except that +completely opaque pixels are gamma encoded according to +the screen_gamma value. Pixels with alpha less than 1.0 +will still have linear components. + +Use this format if you have control over your +compositing software and so don't do other arithmetic +(such as scaling) on the data you get from libpng. Your +compositing software can simply copy opaque pixels to +the output but still has linear values for the +non-opaque pixels. + +In normal compositing, where the alpha channel encodes +partial pixel coverage (as opposed to broad area +translucency), the inaccuracies of the 8-bit +representation of non-opaque pixels are irrelevant. + +You can also try this format if your software is broken; +it might look better. + + PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; +however, all component values, +including the alpha channel are gamma encoded. This is +an appropriate format to try if your software, or more +likely hardware, is totally broken, i.e., if it performs +linear arithmetic directly on gamma encoded values. + +In most cases of broken software or hardware the bug in the final display +manifests as a subtle halo around composited parts of the image. You may not +even perceive this as a halo; the composited part of the image may simply appear +separate from the background, as though it had been cut out of paper and pasted +on afterward. + +If you don't have to deal with bugs in software or hardware, or if you can fix +them, there are three recommended ways of using png_set_alpha_mode(): + + png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG, + screen_gamma); + +You can do color correction on the result (libpng does not currently +support color correction internally). When you handle the alpha channel +you need to undo the gamma encoding and multiply out the alpha. + + png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD, + screen_gamma); + png_set_expand_16(png_ptr); + +If you are using the high level interface, don't call png_set_expand_16(); +instead pass PNG_TRANSFORM_EXPAND_16 to the interface. + +With this mode you can't do color correction, but you can do arithmetic, +including composition and scaling, on the data without further processing. + + png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED, + screen_gamma); + +You can avoid the expansion to 16-bit components with this mode, but you +lose the ability to scale the image or perform other linear arithmetic. +All you can do is compose the result onto a matching output. Since this +mode is libpng-specific you also need to write your own composition +software. + +If you don't need, or can't handle, the alpha channel you can call +png_set_background() to remove it by compositing against a fixed color. Don't +call png_set_strip_alpha() to do this - it will leave spurious pixel values in +transparent parts of this image. + + png_set_background(png_ptr, &background_color, + PNG_BACKGROUND_GAMMA_SCREEN, 0, 1); + +The background_color is an RGB or grayscale value according to the data format +libpng will produce for you. Because you don't yet know the format of the PNG +file, if you call png_set_background at this point you must arrange for the +format produced by libpng to always have 8-bit or 16-bit components and then +store the color as an 8-bit or 16-bit color as appropriate. The color contains +separate gray and RGB component values, so you can let libpng produce gray or +RGB output according to the input format, but low bit depth grayscale images +must always be converted to at least 8-bit format. (Even though low bit depth +grayscale images can't have an alpha channel they can have a transparent +color!) + +You set the transforms you need later, either as flags to the high level +interface or libpng API calls for the low level interface. For reference the +settings and API calls required are: + +8-bit values: + PNG_TRANSFORM_SCALE_16 | PNG_EXPAND + png_set_expand(png_ptr); png_set_scale_16(png_ptr); + + If you must get exactly the same inaccurate results + produced by default in versions prior to libpng-1.5.4, + use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr) + instead. + +16-bit values: + PNG_TRANSFORM_EXPAND_16 + png_set_expand_16(png_ptr); + +In either case palette image data will be expanded to RGB. If you just want +color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr) +to the list. + +Calling png_set_background before the PNG file header is read will not work +prior to libpng-1.5.4. Because the failure may result in unexpected warnings or +errors it is therefore much safer to call png_set_background after the head has +been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be +used with the high level interface. + The high-level read interface At this point there are two ways to proceed; through the high-level @@ -652,8 +910,10 @@ you want to do are limited to the following set: PNG_TRANSFORM_IDENTITY No transformation - PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to - 8 bits + PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to + 8-bit accurately + PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to + 8-bit less accurately PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit samples to bytes @@ -672,6 +932,7 @@ PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples to RGB (or GA to RGBA) + PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits (This excludes setting a background color, doing gamma transformation, quantizing, and setting filler.) If this is the case, simply do this: @@ -740,6 +1001,22 @@ This will process all chunks up to but not including the image data. +This also copies some of the data from the PNG file into the decode structure +for use in later transformations. Important information copied in is: + +1) The PNG file gamma from the gAMA chunk. This overwrites the default value +provided by an earlier call to png_set_gamma or png_set_alpha_mode. + +2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This +damages the information provided by an earlier call to png_set_background +resulting in unexpected behavior. Libpng-1.5.4 no longer does this. + +3) The number of significant bits in each component value. Libpng uses this to +optimize gamma handling by reducing the internal lookup table sizes. + +4) The transparent color information from a tRNS chunk. This can be modified by +a later call to png_set_tRNS. + Querying the info structure Functions are used to get the information from the info_ptr once it @@ -853,6 +1130,11 @@ png_get_ are set directly if they are simple data types, or a pointer into the info_ptr is returned for any complex types. +The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks +is simply returned to give the application information about how the +image was encoded. Libpng itself only does transformations using the file +gamma when combining semitransparent pixels with the background color. + png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette); @@ -864,12 +1146,34 @@ png_get_gAMA(png_ptr, info_ptr, &file_gamma); png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma); - file_gamma - the gamma at which the file is + file_gamma - the gamma at which the file was written (PNG_INFO_gAMA) int_file_gamma - 100,000 times the gamma at which the file is written + png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x, &red_y, + &green_x, &green_y, &blue_x, &blue_y) + png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z, &green_X, + &green_Y, &green_Z, &blue_X, &blue_Y, &blue_Z) + png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x, &int_white_y, + &int_red_x, &int_red_y, &int_green_x, &int_green_y, + &int_blue_x, &int_blue_y) + png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y, + &int_red_Z, &int_green_X, &int_green_Y, &int_green_Z, + &int_blue_X, &int_blue_Y, &int_blue_Z) + + {white,red,green,blue}_{x,y} + A color space encoding specified using the chromaticities + of the end points and the white point. (PNG_INFO_cHRM) + + {red,green,blue}_{X,Y,Z} + A color space encoding specified using the encoding end + points - the CIE tristimulus specification of the intended + color of the red, green and blue channels in the PNG RGB + data. The white point is simply the sum of the three end + points. (PNG_INFO_cHRM) + png_get_sRGB(png_ptr, info_ptr, &srgb_intent); file_srgb_intent - the rendering intent (PNG_INFO_sRGB) @@ -928,7 +1232,8 @@ png_get_bKGD(png_ptr, info_ptr, &background); - background - background color (PNG_VALID_bKGD) + background - background color (of type + png_color_16p) (PNG_VALID_bKGD) valid 16-bit red, green and blue values, regardless of color_type @@ -965,8 +1270,13 @@ (empty string for unknown). Note that the itxt_length, lang, and lang_key - members of the text_ptr structure only exist - when the library is built with iTXt chunk support. + members of the text_ptr structure only exist when the + library is built with iTXt chunk support. Prior to + libpng-1.4.0 the library was built by default without + iTXt support. Also note that when iTXt is supported, + they contain NULL pointers when the "compression" + field contains PNG_TEXT_COMPRESSION_NONE or + PNG_TEXT_COMPRESSION_zTXt. num_text - number of comments (same as num_comments; you can put NULL here @@ -991,10 +1301,10 @@ &unit_type); offset_x - positive offset from the left edge - of the screen + of the screen (can be negative) offset_y - positive offset from the top edge - of the screen + of the screen (can be negative) unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER @@ -1026,6 +1336,7 @@ unit - physical scale units (an integer) width - width of a pixel in physical scale units + (expressed as a string) height - height of a pixel in physical scale units (width and height are strings like "2.54") @@ -1048,6 +1359,12 @@ chunks were read from the PNG file or inserted with the png_set_unknown_chunks() function. + The value of "location" is a bitwise "or" of + + PNG_HAVE_IHDR (0x01) + PNG_HAVE_PLTE (0x02) + PNG_AFTER_IDAT (0x08) + The data from the pHYs chunk can be retrieved in several convenient forms: @@ -1103,7 +1420,7 @@ converted to microns and back without some loss of precision. -For more information, see the png_info definition in png.h and the +For more information, see the PNG specification for chunk contents. Be careful with trusting rowbytes, as some of the transformations could increase the space needed to hold a row (expand, filler, gray_to_rgb, etc.). @@ -1138,18 +1455,21 @@ ways to transform the data will be described in the order that they should occur. This is important, as some of these change the color type and/or bit depth of the data, and some others only work on -certain color types and bit depths. Even though each transformation -checks to see if it has data that it can do something with, you should -make sure to only enable a transformation if it will be valid for the -data. For example, don't swap red and blue on grayscale data. +certain color types and bit depths. -The colors used for the background and transparency values should be -supplied in the same format/depth as the current image data. They -are stored in the same format/depth as the image data in a bKGD or tRNS -chunk, so this is what libpng expects for this data. The colors are -transformed to keep in sync with the image data when an application -calls the png_read_update_info() routine (see below). +Transformations you request are ignored if they don't have any meaning for a +particular input data format. However some transformations can have an effect +as a result of a previous transformation. If you specify a contradictory set of +transformations, for example both adding and removing the alpha channel, you +cannot predict the final result. +The color used for the transparency values should be supplied in the same +format/depth as the current image data. It is stored in the same format/depth +as the image data in a tRNS chunk, so this is what libpng expects for this data. + +The color used for the background value depends on the need_expand argument as +described below. + Data will be decoded into the supplied row buffers packed into bytes unless the library has been told to transform it into another format. For example, 4 bit/pixel paletted or grayscale data will be returned @@ -1158,12 +1478,12 @@ in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha() is called to insert filler bytes, either before or after each RGB triplet. 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant -byte of the color value first, unless png_set_strip_16() is called to +byte of the color value first, unless png_set_scale_16() is called to transform it to regular RGB RGB triplets, or png_set_filler() or png_set_add alpha() is called to insert filler bytes, either before or after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can -be modified with -png_set_filler(), png_set_add_alpha(), or png_set_strip_16(). +be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(), +or png_set_scale_16(). The following code transforms grayscale images of less than 8 to 8 bits, changes paletted images to RGB, and adds a full alpha channel if there is @@ -1189,7 +1509,7 @@ added. It expands the sample depth without changing tRNS to alpha. As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as -png_set_expand(), however, the resultant channels have 16 bits rather than 8. +png_set_expand(); however, the resultant channels have 16 bits rather than 8. Use this when the output color or gray channels are made linear to avoid fairly severe accuracy loss. @@ -1197,27 +1517,32 @@ png_set_expand_16(png_ptr); PNG can have files with 16 bits per channel. If you only can handle -8 bits per channel, this will strip the pixels down to 8 bit. +8 bits per channel, this will strip the pixels down to 8-bit. if (bit_depth == 16) +#if PNG_LIBPNG_VER >= 10504 + png_set_scale_16(png_ptr); +#else png_set_strip_16(png_ptr); +#endif -If, for some reason, you don't need the alpha channel on an image, -and you want to remove it rather than combining it with the background -(but the image author certainly had in mind that you *would* combine -it with the background, so that's what you should probably do): +(The more accurate "png_set_scale_16()" API became available in libpng version +1.5.4). +If you need to process the alpha channel on the image separately from the image +data (for example if you convert it to a bitmap mask) it is possible to have +libpng strip the channel leaving just RGB or gray data: + if (color_type & PNG_COLOR_MASK_ALPHA) png_set_strip_alpha(png_ptr); -See below for png_set_background(), which does the correct composition on a -single opaque color. This is probably what you should do in all cases rather -than use png_set_strip_alpha() - unless you know for sure that it is the wrong -thing to do. +If you strip the alpha channel you need to find some other way of dealing with +the information. If, instead, you want to convert the image to an opaque +version with no alpha channel use png_set_background; see below. As of libpng version 1.5.2, almost all useful expansions are supported, the -major ommissions are convertion of grayscale to indexed images (which can be -done trivially in the application) and convertion of indexed to grayscale (which +major ommissions are conversion of grayscale to indexed images (which can be +done trivially in the application) and conversion of indexed to grayscale (which can be done by a trivial manipulation of the palette.) In the following table, the 01 means grayscale with depth<8, 31 means @@ -1254,8 +1579,7 @@ png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there is no transparency in the original or the final format). "C" means the transformation is obtained by png_set_gray_to_rgb(). - "G" means the transformation is obtained by png_set_rgb_to_gray() or - png_set_rgb_to_Y(). + "G" means the transformation is obtained by png_set_rgb_to_gray(). "P" means the transformation is obtained by png_set_expand_palette_to_rgb(). "p" means the transformation is obtained by png_set_packing(). @@ -1347,8 +1671,8 @@ if (color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_RGB_ALPHA) - png_set_rgb_to_gray_fixed(png_ptr, error_action, - int red_weight, int green_weight); + png_set_rgb_to_gray(png_ptr, error_action, double red_weight, + double green_weight); error_action = 1: silently do the conversion @@ -1361,123 +1685,99 @@ image has any pixel where red != green or red != blue - red_weight: weight of red component times 100000 + red_weight: weight of red component - green_weight: weight of green component times 100000 + green_weight: weight of green component If either weight is negative, default - weights (21268, 71514) are used. + weights are used. +In the corresponding fixed point API the red_weight and green_weight values are +simply scaled by 100,000: + + png_set_rgb_to_gray(png_ptr, error_action, png_fixed_point red_weight, + png_fixed_point green_weight); + If you have set error_action = 1 or 2, you can later check whether the image really was gray, after processing the image rows, with the png_get_rgb_to_gray_status(png_ptr) function. It will return a png_byte that is zero if the image was gray or -1 if there were any non-gray pixels. bKGD and sBIT data +1 if there were any non-gray pixels. Background and sBIT data will be silently converted to grayscale, using the green channel -data, regardless of the error_action setting. +data for sBIT, regardless of the error_action setting. -With red_weight+green_weight<=100000, -the normalized graylevel is computed: +The default values come from the PNG file cHRM chunk if present; otherwise, the +defaults correspond to the ITU-R recommendation 709, and also the sRGB color +space, as recommended in the Charles Poynton's Colour FAQ, +, in section 9: - int rw = red_weight * 65536; - int gw = green_weight * 65536; - int bw = 65536 - (rw + gw); - gray = (rw*red + gw*green + bw*blue)/65536; + -The default values approximate those recommended in the Charles -Poynton's Color FAQ, -Copyright (c) 1998-01-04 Charles Poynton + Y = 0.2126 * R + 0.7152 * G + 0.0722 * B +Previous versions of this document, 1998 through 2002, recommended a slightly +different formula: + Y = 0.212671 * R + 0.715160 * G + 0.072169 * B -Libpng approximates this with integers scaled by 32768: +Libpng uses an integer approximation: Y = (6968 * R + 23434 * G + 2366 * B)/32768 The calculation is done in a linear colorspace, if the image gamma can be determined. -If you have a grayscale and you are using png_set_expand_gray_1_2_4_to_8(), -png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to -a higher bit-depth, you must either supply the background color as a gray -value at the original file bit-depth (need_expand = 1) or else supply the -background color as an RGB triplet at the final, expanded bit depth -(need_expand = 0). Similarly, if you are reading a paletted image, you -must either supply the background color as a palette index (need_expand = 1) -or as an RGB triplet that may or may not be in the palette (need_expand = 0). +The png_set_background() function has been described already; it tells libpng to +composite images with alpha or simple transparency against the supplied +background color. For compatibility with versions of libpng earlier than +libpng-1.5.4 it is recommended that you call the function after reading the file +header, even if you don't want to use the color in a bKGD chunk, if one exists. +If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid), +you may use this color, or supply another color more suitable for +the current display (e.g., the background color from a web page). You +need to tell libpng how the color is represented, both the format of the +component values in the color (the number of bits) and the gamma encoding of the +color. The function takes two arguments, background_gamma_mode and need_expand +to convey this information; however, only two combinations are likely to be +useful: + png_color_16 my_background; png_color_16p image_background; if (png_get_bKGD(png_ptr, info_ptr, &image_background)) png_set_background(png_ptr, image_background, - PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); + PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1); else png_set_background(png_ptr, &my_background, - PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); + PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1); -The png_set_background() function tells libpng to composite images -with alpha or simple transparency against the supplied background -color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid), -you may use this color, or supply another color more suitable for -the current display (e.g., the background color from a web page). You -need to tell libpng whether the color is in the gamma space of the -display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file -(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one -that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't -know why anyone would use this, but it's here). +The second call was described above - my_background is in the format of the +final, display, output produced by libpng. Because you now know the format of +the PNG it is possible to avoid the need to choose either 8-bit or 16-bit +output and to retain palette images (the palette colors will be modified +appropriately and the tRNS chunk removed.) However, if you are doing this, +take great care not to ask for transformations without checking first that +they apply! -To properly display PNG images on any kind of system, the application needs -to know what the display gamma is. Ideally, the user will know this, and -the application will allow them to set it. One method of allowing the user -to set the display gamma separately for each system is to check for a -SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be -correctly set. +In the first call the background color has the original bit depth and color type +of the PNG file. So, for palette images the color is supplied as a palette +index and for low bit greyscale images the color is a reduced bit value in +image_background->gray. -Note that display_gamma is the overall gamma correction required to produce -pleasing results, which depends on the lighting conditions in the surrounding -environment. In a dim or brightly lit room, no compensation other than -the physical gamma exponent of the monitor is needed, while in a dark room -a slightly smaller exponent is better. +If you didn't call png_set_gamma() before reading the file header, for example +if you need your code to remain compatible with older versions of libpng prior +to libpng-1.5.4, this is the place to call it. - double gamma, screen_gamma; +Do not call it if you called png_set_alpha_mode(); doing so will damage the +settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is +supported then you can certainly do png_set_gamma() before reading the PNG +header.) - if (/* We have a user-defined screen - gamma value */) - { - screen_gamma = user_defined_screen_gamma; - } +This API unconditionally sets the screen and file gamma values, so it will +override the value in the PNG file unless it is called before the PNG file +reading starts. For this reason you must always call it with the PNG file +value when you call it in this position: - /* One way that applications can share the same - screen gamma value */ - else if ((gamma_str = getenv("SCREEN_GAMMA")) - != NULL) - { - screen_gamma = (double)atof(gamma_str); - } - - /* If we don't have another value */ - else - { - screen_gamma = 2.2; /* A good guess for a - PC monitor in a bright office or a dim room */ - - screen_gamma = 2.0; /* A good guess for a - PC monitor in a dark room */ - - screen_gamma = 1.7 or 1.0; /* A good - guess for Mac systems */ - } - -The functions png_set_gamma() and its fixed point equivalent -png_set_gamma_fixed() handle gamma transformations of the data. -Pass both the file gamma and the current screen_gamma. If the file does -not have a gamma value, you can pass one anyway if you have an idea what -it is (usually 0.45455 is a good guess for GIF images on PCs). Note -that file gammas are inverted from screen gammas. See the discussions -on gamma in the PNG specification for an excellent description of what -gamma is, and why all applications should support it. It is strongly -recommended that PNG viewers support gamma correction. - if (png_get_gAMA(png_ptr, info_ptr, &file_gamma)) png_set_gamma(png_ptr, screen_gamma, file_gamma); @@ -1489,9 +1789,9 @@ will do that. Note that this is a simple match quantization that merely finds the closest color available. This should work fairly well with optimized palettes, but fairly badly with linear color cubes. If you -pass a palette that is larger then maximum_colors, the file will +pass a palette that is larger than maximum_colors, the file will reduce the number of colors in the palette so it will fit into -maximum_colors. If there is a histogram, it will use it to make +maximum_colors. If there is a histogram, libpng will use it to make more intelligent choices when reducing the palette. If there is no histogram, it may not do as good a job. @@ -1532,7 +1832,7 @@ color_type == PNG_COLOR_TYPE_GRAY_ALPHA) png_set_invert_mono(png_ptr); -PNG files store 16 bit pixels in network byte order (big-endian, +PNG files store 16-bit pixels in network byte order (big-endian, ie. most significant bits first). This code changes the storage to the other way (little-endian, i.e. least significant bits first, the way PCs store them): @@ -1563,7 +1863,7 @@ interlaced images if you do the interlace yourself - the width of the row is the width in 'row_info', not the overall image width. -If supported libpng provides two information routines that you can use to find +If supported, libpng provides two information routines that you can use to find where you are in processing the image: png_get_current_pass_number(png_structp png_ptr); @@ -1607,13 +1907,16 @@ After setting the transformations, libpng can update your png_info structure to reflect any transformations you've requested with this -call. This is most useful to update the info structure's rowbytes +call. + + png_read_update_info(png_ptr, info_ptr); + +This is most useful to update the info structure's rowbytes field so you can use it to allocate your image memory. This function will also update your palette with the correct screen_gamma and -background if these have been given with the calls above. +background if these have been given with the calls above. You may +only call png_read_update_info() once with a particular info_ptr. - png_read_update_info(png_ptr, info_ptr); - After you call png_read_update_info(), you can allocate any memory you need to hold the image. The row data is simply raw byte data for all forms of images. As the actual allocation @@ -1622,7 +1925,7 @@ array of pointers to each row, as it will be needed for some of the functions below. -Remember: Before you call png_read_update_info(), the png_get_ +Remember: Before you call png_read_update_info(), the png_get_*() functions return the values corresponding to the original PNG image. After you call png_read_update_info the values refer to the image that libpng will output. Consequently you must call all the png_set_ @@ -1729,7 +2032,7 @@ If you don't want libpng to handle the interlacing details, just call png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images. -Each of the images is a valid image by itself, however you will almost +Each of the images is a valid image by itself; however, you will almost certainly need to distribute the pixels from each sub-image to the correct place. This is where everything gets very tricky. @@ -1814,7 +2117,7 @@ libpng includes a test program, pngvalid, that illustrates reading and writing of interlaced images. If you can't get interlacing to work in your -code and don't want to leave it to libpng (the recommended approach) see +code and don't want to leave it to libpng (the recommended approach), see how pngvalid.c does it. Finishing a sequential read @@ -1824,15 +2127,39 @@ interested in comments or time, which may be stored either before or after the image data, you should pass the separate png_info struct if you want to keep the comments from before and after the image -separate. If you are not interested, you can pass NULL. +separate. + png_infop end_info = png_create_info_struct(png_ptr); + + if (!end_info) + { + png_destroy_read_struct(&png_ptr, &info_ptr, + (png_infopp)NULL); + return (ERROR); + } + png_read_end(png_ptr, end_info); +If you are not interested, you should still call png_read_end() +but you can pass NULL, avoiding the need to create an end_info structure. + + png_read_end(png_ptr, (png_infop)NULL); + +If you don't call png_read_end(), then your file pointer will be +left pointing to the first chunk after the last IDAT, which is probably +not what you want if you expect to read something beyond the end of +the PNG datastream. + When you are done, you can free all memory allocated by libpng like this: png_destroy_read_struct(&png_ptr, &info_ptr, &end_info); +or, if you didn't create an end_info structure, + + png_destroy_read_struct(&png_ptr, &info_ptr, + (png_infopp)NULL); + It is also possible to individually free the info_ptr members that point to libpng-allocated storage with the following function: @@ -2295,11 +2622,11 @@ #include zlib.h - /* set the zlib compression level */ + /* Set the zlib compression level */ png_set_compression_level(png_ptr, Z_BEST_COMPRESSION); - /* set other zlib parameters */ + /* Set other zlib parameters for compressing IDAT */ png_set_compression_mem_level(png_ptr, 8); png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY); @@ -2307,7 +2634,15 @@ png_set_compression_method(png_ptr, 8); png_set_compression_buffer_size(png_ptr, 8192) -extern PNG_EXPORT(void,png_set_zbuf_size) + /* Set zlib parameters for text compression + * If you don't call these, the parameters + * fall back on those defined for IDAT chunks + */ + png_set_text_compression_mem_level(png_ptr, 8); + png_set_text_compression_strategy(png_ptr, + Z_DEFAULT_STRATEGY); + png_set_text_compression_window_bits(png_ptr, 15); + png_set_text_compression_method(png_ptr, 8); Setting the contents of info for output @@ -2395,6 +2730,28 @@ int_file_gamma - 100,000 times the gamma at which the image was created + png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y, + green_x, green_y, blue_x, blue_y) + png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X, + green_Y, green_Z, blue_X, blue_Y, blue_Z) + png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y, + int_red_x, int_red_y, int_green_x, int_green_y, + int_blue_x, int_blue_y) + png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y, + int_red_Z, int_green_X, int_green_Y, int_green_Z, + int_blue_X, int_blue_Y, int_blue_Z) + + {white,red,green,blue}_{x,y} + A color space encoding specified using the chromaticities + of the end points and the white point. + + {red,green,blue}_{X,Y,Z} + A color space encoding specified using the encoding end + points - the CIE tristimulus specification of the intended + color of the red, green and blue channels in the PNG RGB + data. The white point is simply the sum of the three end + points. + png_set_sRGB(png_ptr, info_ptr, srgb_intent); srgb_intent - the rendering intent @@ -2455,14 +2812,14 @@ trans_alpha - array of alpha (transparency) entries for palette (PNG_INFO_tRNS) + num_trans - number of transparent entries + (PNG_INFO_tRNS) + trans_color - graylevel or color sample values (in order red, green, blue) of the single transparent color for non-paletted images (PNG_INFO_tRNS) - num_trans - number of transparent entries - (PNG_INFO_tRNS) - png_set_hIST(png_ptr, info_ptr, hist); hist - histogram of palette (array of @@ -2475,7 +2832,8 @@ png_set_bKGD(png_ptr, info_ptr, background); - background - background color (PNG_VALID_bKGD) + background - background color (of type + png_color_16p) (PNG_VALID_bKGD) png_set_text(png_ptr, info_ptr, text_ptr, num_text); @@ -2499,9 +2857,15 @@ empty for unknown). text_ptr[i].translated_keyword - keyword in UTF-8 (NULL or empty for unknown). + Note that the itxt_length, lang, and lang_key - members of the text_ptr structure only exist - when the library is built with iTXt chunk support. + members of the text_ptr structure only exist when the + library is built with iTXt chunk support. Prior to + libpng-1.4.0 the library was built by default without + iTXt support. Also note that when iTXt is supported, + they contain NULL pointers when the "compression" + field contains PNG_TEXT_COMPRESSION_NONE or + PNG_TEXT_COMPRESSION_zTXt. num_text - number of comments @@ -2551,6 +2915,7 @@ unit - physical scale units (an integer) width - width of a pixel in physical scale units + expressed as a string height - height of a pixel in physical scale units (width and height are strings like "2.54") @@ -2592,7 +2957,7 @@ specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt any language code or translated keyword will not be written out. -Until text gets around 1000 bytes, it is not worth compressing it. +Until text gets around a few hundred bytes, it is not worth compressing it. After the text has been written out to the file, the compression type is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR, so that it isn't written out again at the end (in case you are calling @@ -2813,7 +3178,7 @@ png_set_shift(png_ptr, &sig_bit); -PNG files store 16 bit pixels in network byte order (big-endian, +PNG files store 16-bit pixels in network byte order (big-endian, ie. most significant bits first). This code would be used if they are supplied the other way (little-endian, i.e. least significant bits first, the way PCs store them): @@ -3202,7 +3567,8 @@ after a longjmp, so the user may want to be careful about doing anything after setjmp returns non-zero besides returning itself. Consult your compiler documentation for more details. For an alternative approach, you -may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net). +may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net), +which is illustrated in pngvalid.c and in contrib/visupng. Custom chunks @@ -3220,8 +3586,11 @@ similarly. Second, check out the sections of libpng that read and write chunks. Try to find a chunk that is similar to yours and use it as a template. More details can be found in the comments inside -the code. It is best to handle unknown chunks in a generic method, -via callback functions, instead of by modifying libpng functions. +the code. It is best to handle private or unknown chunks in a generic method, +via callback functions, instead of by modifying libpng functions. This +is illustrated in pngtest.c, which uses a callback function to handle a +private "vpAg" chunk and the new "sTER" chunk, which are both unknown to +libpng. If you wish to write your own transformation for the data, look through the part of the code that does the transformations, and check out some of @@ -3229,7 +3598,7 @@ transformation to the one you want to add and copy off of it. More details can be found in the comments inside the code itself. -Configuring for 16 bit platforms +Configuring for 16-bit platforms You will want to look into zconf.h to tell zlib (and thus libpng) that it cannot allocate more then 64K at a time. Even if you can, the memory @@ -3249,8 +3618,8 @@ all set. Everything in the library (except for zlib's structure) is expecting far data. You must use the typedefs with the p or pp on the end for pointers (or at least look at them and be careful). Make -note that the rows of data are defined as png_bytepp, which is an -unsigned char far * far *. +note that the rows of data are defined as png_bytepp, which is +an "unsigned char far * far *". Configuring for gui/windowing platforms: @@ -3268,7 +3637,10 @@ The includes that are not needed outside libpng are placed in pngpriv.h, which is only used by the routines inside libpng itself. The files in libpng proper only include pngpriv.h and png.h, which -in turn includes pngconf.h. +in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h. +As of libpng-1.5.0, pngpriv.h also includes three other private header +files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material +that previously appeared in the public headers. Configuring zlib: @@ -3310,8 +3682,28 @@ window_bits); png_set_compression_method(png_ptr, method); + png_set_compression_buffer_size(png_ptr, size); +As of libpng version 1.5.4, additional APIs became +available to set these separately for non-IDAT +compressed chunks such as zTXt, iTXt, and iCCP: + + #include zlib.h + #if PNG_LIBPNG_VER >= 10504 + png_set_text_compression_level(png_ptr, level); + + png_set_text_compression_mem_level(png_ptr, level); + + png_set_text_compression_strategy(png_ptr, + strategy); + + png_set_text_compression_window_bits(png_ptr, + window_bits); + + png_set_text_compression_method(png_ptr, method); + #endif + Controlling row filtering If you want to control whether libpng uses filtering or not, which @@ -3417,8 +3809,8 @@ All the reading and writing specific code are in separate files, so the linker should only grab the files it needs. However, if you want to make sure, or if you are building a stand alone library, all the -reading files start with pngr and all the writing files start with -pngw. The files that don't match either (like png.c, pngtrans.c, etc.) +reading files start with "pngr" and all the writing files start with "pngw". +The files that don't match either (like png.c, pngtrans.c, etc.) are used for both reading and writing, and always need to be included. The progressive reader is in pngpread.c @@ -3537,6 +3929,9 @@ version with leading zero, and release number with leading zero, (e.g., libpng_vn for version 1.0.7 is 10007). +Note that this function does not take a png_ptr, so you can call it +before you've created one. + You can also check which version of png.h you used when compiling your application: @@ -3735,7 +4130,8 @@ allocates. Support for dithering was disabled by default in libpng-1.4.0, because -been well tested and doesn't actually "dither". The code was not +it has not been well tested and doesn't actually "dither". +The code was not removed, however, and could be enabled by building libpng with PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support was reenabled, but the function was renamed png_set_quantize() to @@ -3751,10 +4147,20 @@ From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the function) incorrectly returned a value of type png_uint_32. +Checking for invalid palette index on read or write was added at libpng +1.5.10. When an invalid index is found, libpng issues a benign error. +This is enabled by default but can be disabled in each png_ptr with + + png_set_check_for_invalid_index(png_ptr, allowed); + + allowed - one of + 0: disable + 1: enable + A. Changes that affect users of libpng There are no substantial API changes between the non-deprecated parts of -the 1.4.5 API and the 1.5.0 API, however the ability to directly access +the 1.4.5 API and the 1.5.0 API; however, the ability to directly access the main libpng control structures, png_struct and png_info, deprecated in earlier versions of libpng, has been completely removed from libpng 1.5. @@ -3772,10 +4178,9 @@ to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep. There are changes of form in png.h, including new and changed macros to -declare -parts of the API. Some API functions with arguments that are pointers to -data not modified within the function have been corrected to declare -these arguments with PNG_CONST. +declare parts of the API. Some API functions with arguments that are +pointers to data not modified within the function have been corrected to +declare these arguments with PNG_CONST. Much of the internal use of C macros to control the library build has also changed and some of this is visible in the exported header files, in @@ -3795,9 +4200,9 @@ libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls the application-provided png_longjmp_ptr on the internal, but application -initialized, jmpbuf. It is provided as a convenience to avoid the need -to use the png_jmpbuf macro, which had the unnecessary side effect of -resetting the internal png_longjmp_ptr value. +initialized, longjmp buffer. It is provided as a convenience to avoid +the need to use the png_jmpbuf macro, which had the unnecessary side +effect of resetting the internal png_longjmp_ptr value. libpng 1.5.0 includes a complete fixed point API. By default this is present along with the corresponding floating point API. In general the @@ -3849,30 +4254,63 @@ corresponding function by defining PNG_USE_READ_MACROS or PNG_NO_USE_READ_MACROS before including png.h. Notice that this is only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0 - will lead to a link failure. +will lead to a link failure. +Prior to libpng-1.5.4, the zlib compressor used the same set of parameters +when compressing the IDAT data and textual data such as zTXt and iCCP. +In libpng-1.5.4 we reinitialized the zlib stream for each type of data. +We added five png_set_text_*() functions for setting the parameters to +use with textual data. + +Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED +option was off by default, and slightly inaccurate scaling occurred. +This option can no longer be turned off, and the choice of accurate +or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8() +API for accurate scaling or the old png_set_strip_16_to_8() API for simple +chopping. + +Prior to libpng-1.5.4, the png_set_user_limits() function could only be +used to reduce the width and height limits from the value of +PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said +that it could be used to override them. Now this function will reduce or +increase the limits. + +Starting in libpng-1.5.10, the user limits can be set en masse with the +configuration option PNG_SAFE_LIMITS_SUPPORTED. If this option is enabled, +a set of "safe" limits is applied in pngpriv.h. These can be overridden by +application calls to png_set_user_limits(), png_set_user_chunk_cache_max(), +and/or png_set_user_malloc_max() that increase or decrease the limits. Also, +in libpng-1.5.10 the default width and height limits were increased +from 1,000,000 to 0x7ffffff (i.e., made unlimited). Therefore, the +limits are now + default safe + png_user_width_max 0x7fffffff 1,000,000 + png_user_height_max 0x7fffffff 1,000,000 + png_user_chunk_cache_max 0 (unlimited) 128 + png_user_chunk_malloc_max 0 (unlimited) 8,000,000 + B. Changes to the build and configuration of libpng Details of internal changes to the library code can be found in the CHANGES -file. These will be of no concern to the vast majority of library users or -builders, however the few who configure libpng to a non-default feature -set may need to change how this is done. +file and in the GIT repository logs. These will be of no concern to the vast +majority of library users or builders; however, the few who configure libpng +to a non-default feature set may need to change how this is done. There should be no need for library builders to alter build scripts if these use the distributed build support - configure or the makefiles - -however users of the makefiles may care to update their build scripts +however, users of the makefiles may care to update their build scripts to build pnglibconf.h where the corresponding makefile does not do so. Building libpng with a non-default configuration has changed completely. The old method using pngusr.h should still work correctly even though the -way pngusr.h is used in the build has been changed, however library +way pngusr.h is used in the build has been changed; however, library builders will probably want to examine the changes to take advantage of new capabilities and to simplify their build system. B.1 Specific changes to library configuration capabilities The library now supports a complete fixed point implementation and can -thus be used on systems which have no floating point support or very +thus be used on systems that have no floating point support or very limited or slow support. Previously gamma correction, an essential part of complete PNG support, required reasonably fast floating point. @@ -3888,14 +4326,14 @@ As part of this the mechanism used to choose procedure call standards on those systems that allow a choice has been changed. At present this only affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems -running on Intel processors. As before PNGAPI is defined where required +running on Intel processors. As before, PNGAPI is defined where required to control the exported API functions; however, two new macros, PNGCBAPI and PNGCAPI, are used instead for callback functions (PNGCBAPI) and (PNGCAPI) for functions that must match a C library prototype (currently only png_longjmp_ptr, which must match the C longjmp function.) The new approach is documented in pngconf.h -Despite these changes libpng 1.5.0 only supports the native C function +Despite these changes, libpng 1.5.0 only supports the native C function calling standard on those platforms tested so far (__cdecl on Microsoft Windows). This is because the support requirements for alternative calling conventions seem to no longer exist. Developers who find it @@ -3928,8 +4366,10 @@ /*#undef PNG_feature_SUPPORTED*/ if it is not. Library code consistently checks for the 'SUPPORTED' macro. -It does not, and should not, check for the 'NO' macro which will not -normally be defined even if the feature is not supported. +It does not, and libpng applications should not, check for the 'NO' macro +which will not normally be defined even if the feature is not supported. +The 'NO' macros are only used internally for setting or not setting the +corresponding 'SUPPORTED' macros. Compatibility with the old names is provided as follows: @@ -3964,7 +4404,7 @@ PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating point implementation or the fixed point one. Typically the fixed point implementation is larger and slower than the floating point implementation -on a system that supports floating point, however it may be faster on a +on a system that supports floating point; however, it may be faster on a system which lacks floating point hardware and therefore uses a software emulation. @@ -3986,14 +4426,14 @@ unmodified, default, libpng API and thus would probably fail to link. These mechanisms still work in the configure build and in any makefile -build that builds pnglibconf.h although the feature selection macros +build that builds pnglibconf.h, although the feature selection macros have changed somewhat as described above. In 1.5.0, however, pngusr.h is processed only once, when the exported header file pnglibconf.h is built. -pngconf.h no longer includes pngusr.h, therefore it is ignored after the +pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the build of pnglibconf.h and it is never included in an application build. The rarely used alternative of adding a list of feature macros to the -CFLAGS setting in the build also still works, however the macros will be +CFLAGS setting in the build also still works; however, the macros will be copied to pnglibconf.h and this may produce macro redefinition warnings when the individual C files are compiled. @@ -4003,7 +4443,7 @@ and all known later implementations (often called by subtly different names - nawk and gawk for example) are adequate to build pnglibconf.h. The Sun Microsystems (now Oracle) program 'awk' is an earlier version -and does not work, this may also apply to other systems that have a +and does not work; this may also apply to other systems that have a functioning awk called 'nawk'. Configuration options are now documented in scripts/pnglibconf.dfa. This @@ -4045,8 +4485,8 @@ We also accept patches built from the tar or zip distributions, and simple verbal discriptions of bug fixes, reported either to the -SourceForge bug tracker or to the png-mng-implement at lists.sf.net -mailing list. +SourceForge bug tracker, to the png-mng-implement at lists.sf.net +mailing list, or directly to glennrp. XIII. Coding style @@ -4134,8 +4574,8 @@ /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */ To avoid polluting the global namespace, the names of all exported -functions and variables begin with "png_", and all publicly visible C -preprocessor macros begin with "PNG_". We request that applications that +functions and variables begin with "png_", and all publicly visible C +preprocessor macros begin with "PNG". We request that applications that use libpng *not* begin any of their own symbols with either of these strings. We put a space after each comma and after each semicolon @@ -4151,6 +4591,9 @@ We prefer #ifdef and #ifndef to #if defined() and if !defined() when there is only one macro being tested. +We prefer to express integers that are used as bit masks in hex format, +with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100). + We do not use the TAB character for indentation in the C sources. Lines do not exceed 80 characters. @@ -4159,25 +4602,25 @@ XIV. Y2K Compliance in libpng -March 31, 2011 +July 11, 2012 Since the PNG Development group is an ad-hoc body, we can't make an official declaration. This is your unofficial assurance that libpng from version 0.71 and -upward through 1.5.2 are Y2K compliant. It is my belief that earlier +upward through 1.5.12 are Y2K compliant. It is my belief that earlier versions were also Y2K compliant. -Libpng only has three year fields. One is a 2-byte unsigned integer that -will hold years up to 65535. The other two hold the date in text +Libpng only has two year fields. One is a 2-byte unsigned integer that +will hold years up to 65535. The other holds the date in text format, and will hold years up to 9999. The integer is "png_uint_16 year" in png_time_struct. -The strings are - "png_charp time_buffer" in png_struct and - "near_time_buffer", which is a local character string in png.c. +The string is + "char time_buffer[29]" in png_struct. This will no +longer be used in libpng-1.6.x and will be removed from libpng-1.7.0. There are seven time-related functions: Index: dll/3rdparty/libpng/docs/LICENSE =================================================================== --- dll/3rdparty/libpng/docs/LICENSE (revision 56925) +++ dll/3rdparty/libpng/docs/LICENSE (working copy) @@ -10,8 +10,8 @@ This code is released under the libpng license. -libpng versions 1.2.6, August 15, 2004, through 1.5.2, March 31, 2011, are -Copyright (c) 2004, 2006-2011 Glenn Randers-Pehrson, and are +libpng versions 1.2.6, August 15, 2004, through 1.5.12, July 11, 2012, are +Copyright (c) 2004, 2006-2012 Glenn Randers-Pehrson, and are distributed according to the same disclaimer and license as libpng-1.2.5 with the following individual added to the list of Contributing Authors @@ -108,4 +108,4 @@ Glenn Randers-Pehrson glennrp at users.sourceforge.net -March 31, 2011 +July 11, 2012 Index: dll/3rdparty/libpng/docs/README =================================================================== --- dll/3rdparty/libpng/docs/README (revision 56925) +++ dll/3rdparty/libpng/docs/README (working copy) @@ -1,4 +1,4 @@ -README for libpng version 1.5.2 - March 31, 2011 (shared library 15.0) +README for libpng version 1.5.12 - July 11, 2012 (shared library 15.0) See the note about version numbers near the top of png.h See INSTALL for instructions on how to install libpng. @@ -114,19 +114,16 @@ read mail addressed to the png-implement list, however. Please do not send general questions about PNG. Send them to -the (png-list at ccrc.wustl.edu, subscription required, write to -majordomo at ccrc.wustl.edu with "subscribe png-list" in your message). -On the other hand, -please do not send libpng questions to that address, send them to me -or to the png-implement list. I'll -get them in the end anyway. If you have a question about something +png-mng-misc at lists.sf.net (subscription required; visit +https://lists.sourceforge.net/lists/listinfo/png-mng-misc to +subscribe). If you have a question about something in the PNG specification that is related to using libpng, send it to me. Send me any questions that start with "I was using libpng, and ...". If in doubt, send questions to me. I'll bounce them to others, if necessary. Please do not send suggestions on how to change PNG. We have -been discussing PNG for nine years now, and it is official and +been discussing PNG for sixteen years now, and it is official and finished. If you have suggestions for libpng, however, I'll gladly listen. Even if your suggestion is not used immediately, it may be used later. Index: dll/3rdparty/libpng/png.c =================================================================== --- dll/3rdparty/libpng/png.c (revision 56925) +++ dll/3rdparty/libpng/png.c (working copy) @@ -1,8 +1,8 @@ /* png.c - location for general purpose libpng functions * - * Last changed in libpng 1.5.7 [December 15, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -14,7 +14,7 @@ #include "pngpriv.h" /* Generate a compiler error if there is an old png.h in the search path. */ -typedef png_libpng_version_1_5_9 Your_png_h_is_not_version_1_5_9; +typedef png_libpng_version_1_5_12 Your_png_h_is_not_version_1_5_12; /* Tells libpng that we have already handled the first "num_bytes" bytes * of the PNG file signature. If the PNG data is embedded into another @@ -655,14 +655,14 @@ #else # ifdef __STDC__ return PNG_STRING_NEWLINE \ - "libpng version 1.5.9 - February 18, 2012" PNG_STRING_NEWLINE \ - "Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ + "libpng version 1.5.12 - July 11, 2012" PNG_STRING_NEWLINE \ + "Copyright (c) 1998-2012 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ PNG_STRING_NEWLINE; # else - return "libpng version 1.5.9 - February 18, 2012\ - Copyright (c) 1998-2011 Glenn Randers-Pehrson\ + return "libpng version 1.5.12 - July 11, 2012\ + Copyright (c) 1998-2012 Glenn Randers-Pehrson\ Copyright (c) 1996-1997 Andreas Dilger\ Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; # endif @@ -969,8 +969,8 @@ * and it is certain that it becomes unstable where the end points are close * together. * - * So this code uses the perhaps slighly less optimal but more understandable - * and totally obvious approach of calculating color-scale. + * So this code uses the perhaps slightly less optimal but more + * understandable and totally obvious approach of calculating color-scale. * * This algorithm depends on the precision in white-scale and that is * (1/white-y), so we can immediately see that as white-y approaches 0 the @@ -1467,7 +1467,7 @@ png_pow10(int power) { int recip = 0; - double d = 1; + double d = 1.0; /* Handle negative exponent with a reciprocal at the end because * 10 is exact whereas .1 is inexact in base 2 @@ -1481,7 +1481,7 @@ if (power > 0) { /* Decompose power bitwise. */ - double mult = 10; + double mult = 10.0; do { if (power & 1) d *= mult; @@ -1600,7 +1600,8 @@ { double d; - fp *= 10; + fp *= 10.0; + /* Use modf here, not floor and subtract, so that * the separation is done in one step. At the end * of the loop don't break the number into parts so @@ -1613,7 +1614,7 @@ { d = floor(fp + .5); - if (d > 9) + if (d > 9.0) { /* Rounding up to 10, handle that here. */ if (czero > 0) @@ -1621,9 +1622,10 @@ --czero, d = 1; if (cdigits == 0) --clead; } + else { - while (cdigits > 0 && d > 9) + while (cdigits > 0 && d > 9.0) { int ch = *--ascii; @@ -1648,7 +1650,7 @@ * exponent but take into account the leading * decimal point. */ - if (d > 9) /* cdigits == 0 */ + if (d > 9.0) /* cdigits == 0 */ { if (exp_b10 == (-1)) { @@ -1669,18 +1671,19 @@ ++exp_b10; /* In all cases we output a '1' */ - d = 1; + d = 1.0; } } } fp = 0; /* Guarantees termination below. */ } - if (d == 0) + if (d == 0.0) { ++czero; if (cdigits == 0) ++clead; } + else { /* Included embedded zeros in the digit count. */ @@ -1708,6 +1711,7 @@ above */ --exp_b10; } + *ascii++ = (char)(48 + (int)d), ++cdigits; } } @@ -2040,7 +2044,7 @@ } #endif -#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gammma */ +#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gamma */ /* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ png_fixed_point png_reciprocal(png_fixed_point a) Index: dll/3rdparty/libpng/pngerror.c =================================================================== --- dll/3rdparty/libpng/pngerror.c (revision 56925) +++ dll/3rdparty/libpng/pngerror.c (working copy) @@ -2,7 +2,7 @@ /* pngerror.c - stub functions for i/o and memory allocation * * Last changed in libpng 1.5.8 [February 1, 2011] - * Copyright (c) 1998-2012 Glenn Randers-Pehrson + * Copyright (c) 1998-2011 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * Index: dll/3rdparty/libpng/pngpread.c =================================================================== --- dll/3rdparty/libpng/pngpread.c (revision 56925) +++ dll/3rdparty/libpng/pngpread.c (working copy) @@ -1,8 +1,8 @@ /* pngpread.c - read a png file in push mode * - * Last changed in libpng 1.5.9 [February 18, 2012] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -128,30 +128,6 @@ break; } -#ifdef PNG_READ_tEXt_SUPPORTED - case PNG_READ_tEXt_MODE: - { - png_push_read_tEXt(png_ptr, info_ptr); - break; - } - -#endif -#ifdef PNG_READ_zTXt_SUPPORTED - case PNG_READ_zTXt_MODE: - { - png_push_read_zTXt(png_ptr, info_ptr); - break; - } - -#endif -#ifdef PNG_READ_iTXt_SUPPORTED - case PNG_READ_iTXt_MODE: - { - png_push_read_iTXt(png_ptr, info_ptr); - break; - } - -#endif case PNG_SKIP_MODE: { png_push_crc_finish(png_ptr); @@ -176,7 +152,7 @@ png_push_read_sig(png_structp png_ptr, png_infop info_ptr) { png_size_t num_checked = png_ptr->sig_bytes, - num_to_check = 8 - num_checked; + num_to_check = 8 - num_checked; if (png_ptr->buffer_size < num_to_check) { @@ -196,6 +172,7 @@ else png_error(png_ptr, "PNG file corrupted by ASCII conversion"); } + else { if (png_ptr->sig_bytes >= 8) @@ -305,8 +282,8 @@ png_error(png_ptr, "Missing PLTE before IDAT"); } } +#endif -#endif else if (chunk_name == png_PLTE) { if (png_ptr->push_length + 4 > png_ptr->buffer_size) @@ -543,7 +520,7 @@ return; } - png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length); + png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length); } #endif @@ -556,7 +533,7 @@ return; } - png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length); + png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length); } #endif @@ -569,10 +546,11 @@ return; } - png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length); + png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length); } #endif + else { if (png_ptr->push_length + 4 > png_ptr->buffer_size) @@ -580,7 +558,7 @@ png_push_save_buffer(png_ptr); return; } - png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length); + png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length); } png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER; @@ -620,6 +598,7 @@ png_ptr->save_buffer_size -= save_size; png_ptr->save_buffer_ptr += save_size; } + if (png_ptr->skip_length && png_ptr->current_buffer_size) { png_size_t save_size = png_ptr->current_buffer_size; @@ -641,6 +620,7 @@ png_ptr->current_buffer_size -= save_size; png_ptr->current_buffer_ptr += save_size; } + if (!png_ptr->skip_length) { if (png_ptr->buffer_size < 4) @@ -663,6 +643,7 @@ return; ptr = buffer; + if (png_ptr->save_buffer_size) { png_size_t save_size; @@ -680,6 +661,7 @@ png_ptr->save_buffer_size -= save_size; png_ptr->save_buffer_ptr += save_size; } + if (length && png_ptr->current_buffer_size) { png_size_t save_size; @@ -709,6 +691,7 @@ png_bytep dp; istop = png_ptr->save_buffer_size; + for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer; i < istop; i++, sp++, dp++) { @@ -716,6 +699,7 @@ } } } + if (png_ptr->save_buffer_size + png_ptr->current_buffer_size > png_ptr->save_buffer_max) { @@ -742,6 +726,7 @@ png_free(png_ptr, old_buffer); png_ptr->save_buffer_max = new_max; } + if (png_ptr->current_buffer_size) { png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size, @@ -749,6 +734,7 @@ png_ptr->save_buffer_size += png_ptr->current_buffer_size; png_ptr->current_buffer_size = 0; } + png_ptr->save_buffer_ptr = png_ptr->save_buffer; png_ptr->buffer_size = 0; } @@ -850,6 +836,7 @@ png_ptr->current_buffer_size -= save_size; png_ptr->current_buffer_ptr += save_size; } + if (!png_ptr->idat_size) { if (png_ptr->buffer_size < 4) @@ -1263,522 +1250,7 @@ #endif /* PNG_READ_INTERLACING_SUPPORTED */ } -#ifdef PNG_READ_tEXt_SUPPORTED void /* PRIVATE */ -png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 - length) -{ - if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND)) - { - PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */ - png_error(png_ptr, "Out of place tEXt"); - /* NOT REACHED */ - } - -#ifdef PNG_MAX_MALLOC_64K - png_ptr->skip_length = 0; /* This may not be necessary */ - - if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */ - { - png_warning(png_ptr, "tEXt chunk too large to fit in memory"); - png_ptr->skip_length = length - (png_uint_32)65535L; - length = (png_uint_32)65535L; - } -#endif - - png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1); - png_ptr->current_text[length] = '\0'; - png_ptr->current_text_ptr = png_ptr->current_text; - png_ptr->current_text_size = (png_size_t)length; - png_ptr->current_text_left = (png_size_t)length; - png_ptr->process_mode = PNG_READ_tEXt_MODE; -} - -void /* PRIVATE */ -png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr) -{ - if (png_ptr->buffer_size && png_ptr->current_text_left) - { - png_size_t text_size; - - if (png_ptr->buffer_size < png_ptr->current_text_left) - text_size = png_ptr->buffer_size; - - else - text_size = png_ptr->current_text_left; - - png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size); - png_ptr->current_text_left -= text_size; - png_ptr->current_text_ptr += text_size; - } - if (!(png_ptr->current_text_left)) - { - png_textp text_ptr; - png_charp text; - png_charp key; - int ret; - - if (png_ptr->buffer_size < 4) - { - png_push_save_buffer(png_ptr); - return; - } - - png_push_crc_finish(png_ptr); - -#ifdef PNG_MAX_MALLOC_64K - if (png_ptr->skip_length) - return; -#endif - - key = png_ptr->current_text; - - for (text = key; *text; text++) - /* Empty loop */ ; - - if (text < key + png_ptr->current_text_size) - text++; - - text_ptr = (png_textp)png_malloc(png_ptr, png_sizeof(png_text)); - text_ptr->compression = PNG_TEXT_COMPRESSION_NONE; - text_ptr->key = key; - text_ptr->itxt_length = 0; - text_ptr->lang = NULL; - text_ptr->lang_key = NULL; - text_ptr->text = text; - - ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1); - - png_free(png_ptr, key); - png_free(png_ptr, text_ptr); - png_ptr->current_text = NULL; - - if (ret) - png_warning(png_ptr, "Insufficient memory to store text chunk"); - } -} -#endif - -#ifdef PNG_READ_zTXt_SUPPORTED -void /* PRIVATE */ -png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 - length) -{ - if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND)) - { - PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */ - png_error(png_ptr, "Out of place zTXt"); - /* NOT REACHED */ - } - -#ifdef PNG_MAX_MALLOC_64K - /* We can't handle zTXt chunks > 64K, since we don't have enough space - * to be able to store the uncompressed data. Actually, the threshold - * is probably around 32K, but it isn't as definite as 64K is. - */ - if (length > (png_uint_32)65535L) - { - png_warning(png_ptr, "zTXt chunk too large to fit in memory"); - png_push_crc_skip(png_ptr, length); - return; - } -#endif - - png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1); - png_ptr->current_text[length] = '\0'; - png_ptr->current_text_ptr = png_ptr->current_text; - png_ptr->current_text_size = (png_size_t)length; - png_ptr->current_text_left = (png_size_t)length; - png_ptr->process_mode = PNG_READ_zTXt_MODE; -} - -void /* PRIVATE */ -png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr) -{ - if (png_ptr->buffer_size && png_ptr->current_text_left) - { - png_size_t text_size; - - if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left) - text_size = png_ptr->buffer_size; - - else - text_size = png_ptr->current_text_left; - - png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size); - png_ptr->current_text_left -= text_size; - png_ptr->current_text_ptr += text_size; - } - if (!(png_ptr->current_text_left)) - { - png_textp text_ptr; - png_charp text; - png_charp key; - int ret; - png_size_t text_size, key_size; - - if (png_ptr->buffer_size < 4) - { - png_push_save_buffer(png_ptr); - return; - } - - png_push_crc_finish(png_ptr); - - key = png_ptr->current_text; - - for (text = key; *text; text++) - /* Empty loop */ ; - - /* zTXt can't have zero text */ - if (text >= key + png_ptr->current_text_size) - { - png_ptr->current_text = NULL; - png_free(png_ptr, key); - return; - } - - text++; - - if (*text != PNG_TEXT_COMPRESSION_zTXt) /* Check compression byte */ - { - png_ptr->current_text = NULL; - png_free(png_ptr, key); - return; - } - - text++; - - png_ptr->zstream.next_in = (png_bytep)text; - png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size - - (text - key)); - png_ptr->zstream.next_out = png_ptr->zbuf; - png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; - - key_size = text - key; - text_size = 0; - text = NULL; - ret = Z_STREAM_END; - - while (png_ptr->zstream.avail_in) - { - ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH); - if (ret != Z_OK && ret != Z_STREAM_END) - { - inflateReset(&png_ptr->zstream); - png_ptr->zstream.avail_in = 0; - png_ptr->current_text = NULL; - png_free(png_ptr, key); - png_free(png_ptr, text); - return; - } - - if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END) - { - if (text == NULL) - { - text = (png_charp)png_malloc(png_ptr, - (png_ptr->zbuf_size - - png_ptr->zstream.avail_out + key_size + 1)); - - png_memcpy(text + key_size, png_ptr->zbuf, - png_ptr->zbuf_size - png_ptr->zstream.avail_out); - - png_memcpy(text, key, key_size); - - text_size = key_size + png_ptr->zbuf_size - - png_ptr->zstream.avail_out; - - *(text + text_size) = '\0'; - } - - else - { - png_charp tmp; - - tmp = text; - text = (png_charp)png_malloc(png_ptr, text_size + - (png_ptr->zbuf_size - - png_ptr->zstream.avail_out + 1)); - - png_memcpy(text, tmp, text_size); - png_free(png_ptr, tmp); - - png_memcpy(text + text_size, png_ptr->zbuf, - png_ptr->zbuf_size - png_ptr->zstream.avail_out); - - text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out; - *(text + text_size) = '\0'; - } - - if (ret != Z_STREAM_END) - { - png_ptr->zstream.next_out = png_ptr->zbuf; - png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; - } - } - else - { - break; - } - - if (ret == Z_STREAM_END) - break; - } - - inflateReset(&png_ptr->zstream); - png_ptr->zstream.avail_in = 0; - - if (ret != Z_STREAM_END) - { - png_ptr->current_text = NULL; - png_free(png_ptr, key); - png_free(png_ptr, text); - return; - } - - png_ptr->current_text = NULL; - png_free(png_ptr, key); - key = text; - text += key_size; - - text_ptr = (png_textp)png_malloc(png_ptr, - png_sizeof(png_text)); - text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt; - text_ptr->key = key; - text_ptr->itxt_length = 0; - text_ptr->lang = NULL; - text_ptr->lang_key = NULL; - text_ptr->text = text; - - ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1); - - png_free(png_ptr, key); - png_free(png_ptr, text_ptr); - - if (ret) - png_warning(png_ptr, "Insufficient memory to store text chunk"); - } -} -#endif - -#ifdef PNG_READ_iTXt_SUPPORTED -void /* PRIVATE */ -png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 - length) -{ - if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND)) - { - PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */ - png_error(png_ptr, "Out of place iTXt"); - /* NOT REACHED */ - } - -#ifdef PNG_MAX_MALLOC_64K - png_ptr->skip_length = 0; /* This may not be necessary */ - - if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */ - { - png_warning(png_ptr, "iTXt chunk too large to fit in memory"); - png_ptr->skip_length = length - (png_uint_32)65535L; - length = (png_uint_32)65535L; - } -#endif - - png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1); - png_ptr->current_text[length] = '\0'; - png_ptr->current_text_ptr = png_ptr->current_text; - png_ptr->current_text_size = (png_size_t)length; - png_ptr->current_text_left = (png_size_t)length; - png_ptr->process_mode = PNG_READ_iTXt_MODE; -} - -void /* PRIVATE */ -png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr) -{ - - if (png_ptr->buffer_size && png_ptr->current_text_left) - { - png_size_t text_size; - - if (png_ptr->buffer_size < png_ptr->current_text_left) - text_size = png_ptr->buffer_size; - - else - text_size = png_ptr->current_text_left; - - png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size); - png_ptr->current_text_left -= text_size; - png_ptr->current_text_ptr += text_size; - } - - if (!(png_ptr->current_text_left)) - { - png_textp text_ptr; - png_charp key; - int comp_flag; - png_charp lang; - png_charp lang_key; - png_charp text; - int ret; - - if (png_ptr->buffer_size < 4) - { - png_push_save_buffer(png_ptr); - return; - } - - png_push_crc_finish(png_ptr); - -#ifdef PNG_MAX_MALLOC_64K - if (png_ptr->skip_length) - return; -#endif - - key = png_ptr->current_text; - - for (lang = key; *lang; lang++) - /* Empty loop */ ; - - if (lang < key + png_ptr->current_text_size - 3) - lang++; - - comp_flag = *lang++; - lang++; /* Skip comp_type, always zero */ - - for (lang_key = lang; *lang_key; lang_key++) - /* Empty loop */ ; - - lang_key++; /* Skip NUL separator */ - - text=lang_key; - - if (lang_key < key + png_ptr->current_text_size - 1) - { - for (; *text; text++) - /* Empty loop */ ; - } - - if (text < key + png_ptr->current_text_size) - text++; - - text_ptr = (png_textp)png_malloc(png_ptr, - png_sizeof(png_text)); - - text_ptr->compression = comp_flag + 2; - text_ptr->key = key; - text_ptr->lang = lang; - text_ptr->lang_key = lang_key; - text_ptr->text = text; - text_ptr->text_length = 0; - text_ptr->itxt_length = png_strlen(text); - - ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1); - - png_ptr->current_text = NULL; - - png_free(png_ptr, text_ptr); - if (ret) - png_warning(png_ptr, "Insufficient memory to store iTXt chunk"); - } -} -#endif - -/* This function is called when we haven't found a handler for this - * chunk. If there isn't a problem with the chunk itself (ie a bad chunk - * name or a critical chunk), the chunk is (currently) silently ignored. - */ -void /* PRIVATE */ -png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 - length) -{ - png_uint_32 skip = 0; - png_uint_32 chunk_name = png_ptr->chunk_name; - - if (PNG_CHUNK_CRITICAL(chunk_name)) - { -#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED - if (png_chunk_unknown_handling(png_ptr, chunk_name) != - PNG_HANDLE_CHUNK_ALWAYS -#ifdef PNG_READ_USER_CHUNKS_SUPPORTED - && png_ptr->read_user_chunk_fn == NULL -#endif - ) -#endif - png_chunk_error(png_ptr, "unknown critical chunk"); - - PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */ - } - -#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED - /* TODO: the code below is apparently just using the - * png_struct::unknown_chunk member as a temporarily variable, it should be - * possible to eliminate both it and the temporary buffer. - */ - if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS) - { -#ifdef PNG_MAX_MALLOC_64K - if (length > 65535) - { - png_warning(png_ptr, "unknown chunk too large to fit in memory"); - skip = length - 65535; - length = 65535; - } -#endif - /* This is just a record for the user; libpng doesn't use the character - * form of the name. - */ - PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name); - - png_ptr->unknown_chunk.size = length; - - if (length == 0) - png_ptr->unknown_chunk.data = NULL; - - else - { - png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, - png_ptr->unknown_chunk.size); - png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, - png_ptr->unknown_chunk.size); - } - -#ifdef PNG_READ_USER_CHUNKS_SUPPORTED - if (png_ptr->read_user_chunk_fn != NULL) - { - /* Callback to user unknown chunk handler */ - int ret; - ret = (*(png_ptr->read_user_chunk_fn)) - (png_ptr, &png_ptr->unknown_chunk); - - if (ret < 0) - png_chunk_error(png_ptr, "error in user chunk"); - - if (ret == 0) - { - if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name)) - if (png_chunk_unknown_handling(png_ptr, chunk_name) != - PNG_HANDLE_CHUNK_ALWAYS) - png_chunk_error(png_ptr, "unknown critical chunk"); - png_set_unknown_chunks(png_ptr, info_ptr, - &png_ptr->unknown_chunk, 1); - } - } - - else -#endif - png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1); - png_free(png_ptr, png_ptr->unknown_chunk.data); - png_ptr->unknown_chunk.data = NULL; - } - - else -#endif - skip=length; - png_push_crc_skip(png_ptr, skip); -} - -void /* PRIVATE */ png_push_have_info(png_structp png_ptr, png_infop info_ptr) { if (png_ptr->info_fn != NULL) Index: dll/3rdparty/libpng/pngpriv.h =================================================================== --- dll/3rdparty/libpng/pngpriv.h (revision 56925) +++ dll/3rdparty/libpng/pngpriv.h (working copy) @@ -2,11 +2,11 @@ /* pngpriv.h - private declarations for use inside libpng * * For conditions of distribution and use, see copyright notice in png.h - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * - * Last changed in libpng 1.5.7 [December 15, 2011] + * Last changed in libpng 1.5.10 [March 29, 2012] * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer @@ -133,6 +133,46 @@ # define PNG_DLL_EXPORT #endif +/* SECURITY and SAFETY: + * + * By default libpng is built without any internal limits on image size, + * individual heap (png_malloc) allocations or the total amount of memory used. + * If PNG_SAFE_LIMITS_SUPPORTED is defined, however, the limits below are used + * (unless individually overridden). These limits are believed to be fairly + * safe, but builders of secure systems should verify the values against the + * real system capabilities. + */ + +#ifdef PNG_SAFE_LIMITS_SUPPORTED + /* 'safe' limits */ +# ifndef PNG_USER_WIDTH_MAX +# define PNG_USER_WIDTH_MAX 1000000 +# endif +# ifndef PNG_USER_HEIGHT_MAX +# define PNG_USER_HEIGHT_MAX 1000000 +# endif +# ifndef PNG_USER_CHUNK_CACHE_MAX +# define PNG_USER_CHUNK_CACHE_MAX 128 +# endif +# ifndef PNG_USER_CHUNK_MALLOC_MAX +# define PNG_USER_CHUNK_MALLOC_MAX 8000000 +# endif +#else + /* values for no limits */ +# ifndef PNG_USER_WIDTH_MAX +# define PNG_USER_WIDTH_MAX 0x7fffffff +# endif +# ifndef PNG_USER_HEIGHT_MAX +# define PNG_USER_HEIGHT_MAX 0x7fffffff +# endif +# ifndef PNG_USER_CHUNK_CACHE_MAX +# define PNG_USER_CHUNK_CACHE_MAX 0 +# endif +# ifndef PNG_USER_CHUNK_MALLOC_MAX +# define PNG_USER_CHUNK_MALLOC_MAX 0 +# endif +#endif + /* This is used for 16 bit gamma tables - only the top level pointers are const, * this could be changed: */ @@ -426,6 +466,7 @@ #define PNG_BACKGROUND_IS_GRAY 0x800 #define PNG_HAVE_PNG_SIGNATURE 0x1000 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */ +#define PNG_HAVE_iCCP 0x4000 /* Flags for the transformations the PNG library does on the image data */ #define PNG_BGR 0x0001 @@ -1218,10 +1259,8 @@ png_uint_32 length)); #endif -#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED PNG_EXTERN void png_handle_unknown PNGARG((png_structp png_ptr, png_infop info_ptr, png_uint_32 length)); -#endif PNG_EXTERN void png_check_chunk_name PNGARG((png_structp png_ptr, png_uint_32 chunk_name)); @@ -1355,6 +1394,13 @@ int color_type, int interlace_type, int compression_type, int filter_type)); +/* Added at libpng version 1.5.10 */ +#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \ + defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED) +PNG_EXTERN void png_do_check_palette_indexes PNGARG((png_structp png_ptr, + png_row_infop row_info)); +#endif + /* Free all memory used by the read (old method - NOT DLL EXPORTED) */ PNG_EXTERN void png_read_destroy PNGARG((png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr)); Index: dll/3rdparty/libpng/pngread.c =================================================================== --- dll/3rdparty/libpng/pngread.c (revision 56925) +++ dll/3rdparty/libpng/pngread.c (working copy) @@ -1,8 +1,8 @@ /* pngread.c - read a PNG file * - * Last changed in libpng 1.5.7 [December 15, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.10 [March 8, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -67,15 +67,11 @@ png_ptr->user_width_max = PNG_USER_WIDTH_MAX; png_ptr->user_height_max = PNG_USER_HEIGHT_MAX; -# ifdef PNG_USER_CHUNK_CACHE_MAX /* Added at libpng-1.2.43 and 1.4.0 */ png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX; -# endif -# ifdef PNG_SET_USER_CHUNK_MALLOC_MAX /* Added at libpng-1.2.43 and 1.4.1 */ png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX; -# endif #endif #ifdef PNG_SETJMP_SUPPORTED @@ -805,6 +801,13 @@ png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */ +#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED + /* Report invalid palette index; added at libng-1.5.10 */ + if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && + png_ptr->num_palette_max > png_ptr->num_palette) + png_benign_error(png_ptr, "Read palette index exceeding num_palette"); +#endif + do { png_uint_32 length = png_read_chunk_header(png_ptr); @@ -1070,12 +1073,6 @@ png_free(png_ptr, png_ptr->save_buffer); #endif -#ifdef PNG_PROGRESSIVE_READ_SUPPORTED -#ifdef PNG_TEXT_SUPPORTED - png_free(png_ptr, png_ptr->current_text); -#endif /* PNG_TEXT_SUPPORTED */ -#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */ - /* Save the important info out of the png_struct, in case it is * being used again. */ Index: dll/3rdparty/libpng/pngrtran.c =================================================================== --- dll/3rdparty/libpng/pngrtran.c (revision 56925) +++ dll/3rdparty/libpng/pngrtran.c (working copy) @@ -1,8 +1,8 @@ /* pngrtran.c - transforms the data in a row for PNG readers * - * Last changed in libpng 1.5.7 [December 15, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -1770,8 +1770,8 @@ int num_palette = png_ptr->num_palette; int i; - /*NOTE: there are other transformations that should probably be in here - * too. + /* NOTE: there are other transformations that should probably be in + * here too. */ for (i = 0; i < num_palette; i++) { @@ -1830,12 +1830,15 @@ #ifdef PNG_READ_SHIFT_SUPPORTED if ((png_ptr->transformations & PNG_SHIFT) && + !(png_ptr->transformations & PNG_EXPAND) && (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) { int i; int istop = png_ptr->num_palette; int shift = 8 - png_ptr->sig_bit.red; + png_ptr->transformations &= ~PNG_SHIFT; + /* significant bits can be in the range 1 to 7 for a meaninful result, if * the number of significant bits is 0 then no shift is done (this is an * error condition which is silently ignored.) @@ -2274,7 +2277,7 @@ #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED - /*NOTE: moved here in 1.5.4 (from much later in this list.) */ + /* NOTE: moved here in 1.5.4 (from much later in this list.) */ if ((png_ptr->transformations & PNG_GRAY_TO_RGB) && (png_ptr->mode & PNG_BACKGROUND_IS_GRAY)) png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); @@ -2296,6 +2299,13 @@ png_do_unpack(row_info, png_ptr->row_buf + 1); #endif +#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED + /* Added at libpng-1.5.10 */ + if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && + png_ptr->num_palette_max >= 0) + png_do_check_palette_indexes(png_ptr, row_info); +#endif + #ifdef PNG_READ_BGR_SUPPORTED if (png_ptr->transformations & PNG_BGR) png_do_bgr(row_info, png_ptr->row_buf + 1); @@ -3293,7 +3303,7 @@ if (red != green || red != blue) { rgb_error |= 1; - /*NOTE: this is the historical approach which simply + /* NOTE: this is the historical approach which simply * truncates the results. */ *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15); Index: dll/3rdparty/libpng/pngrutil.c =================================================================== --- dll/3rdparty/libpng/pngrutil.c (revision 56925) +++ dll/3rdparty/libpng/pngrutil.c (working copy) @@ -1,7 +1,7 @@ /* pngrutil.c - utilities to read a PNG file * - * Last changed in libpng 1.5.9 [February 18, 2012] + * Last changed in libpng 1.5.10 [March 8, 2012] * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) @@ -434,14 +434,12 @@ */ if (prefix_size >= (~(png_size_t)0) - 1 || expanded_size >= (~(png_size_t)0) - 1 - prefix_size -#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED +#ifdef PNG_USER_LIMITS_SUPPORTED || (png_ptr->user_chunk_malloc_max && (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1)) #else -# ifdef PNG_USER_CHUNK_MALLOC_MAX || ((PNG_USER_CHUNK_MALLOC_MAX > 0) && prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1) -# endif #endif ) png_warning(png_ptr, "Exceeded size limit while expanding chunk"); @@ -1259,13 +1257,16 @@ /* Should be an error, but we can cope with it */ png_warning(png_ptr, "Out of place iCCP chunk"); - if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)) + if ((png_ptr->mode & PNG_HAVE_iCCP) || (info_ptr != NULL && + (info_ptr->valid & (PNG_INFO_iCCP|PNG_INFO_sRGB)))) { png_warning(png_ptr, "Duplicate iCCP chunk"); png_crc_finish(png_ptr, length); return; } + png_ptr->mode |= PNG_HAVE_iCCP; + #ifdef PNG_MAX_MALLOC_64K if (length > (png_uint_32)65535L) { @@ -1795,16 +1796,16 @@ return; } - num = length / 2 ; - - if (num != (unsigned int)png_ptr->num_palette || num > - (unsigned int)PNG_MAX_PALETTE_LENGTH) + if (length > 2*PNG_MAX_PALETTE_LENGTH || + length != (unsigned int) (2*png_ptr->num_palette)) { png_warning(png_ptr, "Incorrect hIST chunk length"); png_crc_finish(png_ptr, length); return; } + num = length / 2 ; + for (i = 0; i < num; i++) { png_byte buf[2]; Index: dll/3rdparty/libpng/pngset.c =================================================================== --- dll/3rdparty/libpng/pngset.c (revision 56925) +++ dll/3rdparty/libpng/pngset.c (working copy) @@ -1,8 +1,8 @@ /* pngset.c - storage of image information into info struct * - * Last changed in libpng 1.5.7 [December 15, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -149,7 +149,7 @@ * possible for 1/gamma to overflow the limit of 21474 and this means the * gamma value must be at least 5/100000 and hence at most 20000.0. For * safety the limits here are a little narrower. The values are 0.00016 to - * 6250.0, which are truly ridiculous gammma values (and will produce + * 6250.0, which are truly ridiculous gamma values (and will produce * displays that are all black or all white.) */ if (file_gamma < 16 || file_gamma > 625000000) @@ -692,24 +692,28 @@ */ if (info_ptr->num_text + num_text > info_ptr->max_text) { + int old_max_text = info_ptr->max_text; + int old_num_text = info_ptr->num_text; + if (info_ptr->text != NULL) { png_textp old_text; - int old_max; - old_max = info_ptr->max_text; info_ptr->max_text = info_ptr->num_text + num_text + 8; old_text = info_ptr->text; + info_ptr->text = (png_textp)png_malloc_warn(png_ptr, (png_size_t)(info_ptr->max_text * png_sizeof(png_text))); if (info_ptr->text == NULL) { - png_free(png_ptr, old_text); + /* Restore to previous condition */ + info_ptr->max_text = old_max_text; + info_ptr->text = old_text; return(1); } - png_memcpy(info_ptr->text, old_text, (png_size_t)(old_max * + png_memcpy(info_ptr->text, old_text, (png_size_t)(old_max_text * png_sizeof(png_text))); png_free(png_ptr, old_text); } @@ -721,7 +725,12 @@ info_ptr->text = (png_textp)png_malloc_warn(png_ptr, (png_size_t)(info_ptr->max_text * png_sizeof(png_text))); if (info_ptr->text == NULL) + { + /* Restore to previous condition */ + info_ptr->num_text = old_num_text; + info_ptr->max_text = old_max_text; return(1); + } info_ptr->free_me |= PNG_FREE_TEXT; } @@ -1281,4 +1290,22 @@ png_ptr->flags &= ~PNG_FLAG_BENIGN_ERRORS_WARN; } #endif /* PNG_BENIGN_ERRORS_SUPPORTED */ + +#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED +/* Whether to report invalid palette index; added at libng-1.5.10 + * allowed - one of 0: disable; 1: enable + */ +void PNGAPI +png_set_check_for_invalid_index(png_structp png_ptr, int allowed) +{ + png_debug(1, "in png_set_check_for_invalid_index"); + + if (allowed) + png_ptr->num_palette_max = 0; + + else + png_ptr->num_palette_max = -1; +} +#endif + #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */ Index: dll/3rdparty/libpng/pngstruct.h =================================================================== --- dll/3rdparty/libpng/pngstruct.h (revision 56925) +++ dll/3rdparty/libpng/pngstruct.h (working copy) @@ -1,7 +1,7 @@ /* pngstruct.h - header file for PNG reference library * - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -121,6 +121,12 @@ png_uint_32 crc; /* current chunk CRC value */ png_colorp palette; /* palette from the input file */ png_uint_16 num_palette; /* number of color entries in palette */ + +/* Added at libpng-1.5.10 */ +#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED + int num_palette_max; /* maximum palette index found in IDAT */ +#endif + png_uint_16 num_trans; /* number of transparency values */ png_byte compression; /* file compression type (always 0) */ png_byte filter; /* file filter type (always 0) */ @@ -211,13 +217,6 @@ int process_mode; /* what push library is currently doing */ int cur_palette; /* current push library palette index */ -# ifdef PNG_TEXT_SUPPORTED - png_size_t current_text_size; /* current size of text input data */ - png_size_t current_text_left; /* how much text left to read in input */ - png_charp current_text; /* current text chunk buffer */ - png_charp current_text_ptr; /* current location in current_text */ -# endif /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_TEXT_SUPPORTED */ - #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */ #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__) @@ -249,6 +248,7 @@ #endif #ifdef PNG_TIME_RFC1123_SUPPORTED + /* This is going to be unused in libpng16 and removed from libpng17 */ char time_buffer[29]; /* String to hold RFC 1123 time text */ #endif Index: dll/3rdparty/libpng/pngtest.c =================================================================== --- dll/3rdparty/libpng/pngtest.c (revision 56925) +++ dll/3rdparty/libpng/pngtest.c (working copy) @@ -1817,4 +1817,4 @@ } /* Generate a compiler error if there is an old png.h in the search path. */ -typedef png_libpng_version_1_5_9 Your_png_h_is_not_version_1_5_9; +typedef png_libpng_version_1_5_12 Your_png_h_is_not_version_1_5_12; Index: dll/3rdparty/libpng/pngtrans.c =================================================================== --- dll/3rdparty/libpng/pngtrans.c (revision 56925) +++ dll/3rdparty/libpng/pngtrans.c (working copy) @@ -1,8 +1,8 @@ /* pngtrans.c - transforms the data in a row (used by both readers and writers) * - * Last changed in libpng 1.5.4 [July 7, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -619,6 +619,109 @@ } #endif /* PNG_READ_BGR_SUPPORTED or PNG_WRITE_BGR_SUPPORTED */ +#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \ + defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED) +/* Added at libpng-1.5.10 */ +void /* PRIVATE */ +png_do_check_palette_indexes(png_structp png_ptr, png_row_infop row_info) +{ + if (png_ptr->num_palette < (1 << row_info->bit_depth) && + png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */ + { + /* Calculations moved outside switch in an attempt to stop different + * compiler warnings. 'padding' is in *bits* within the last byte, it is + * an 'int' because pixel_depth becomes an 'int' in the expression below, + * and this calculation is used because it avoids warnings that other + * forms produced on either GCC or MSVC. + */ + int padding = (-row_info->pixel_depth * row_info->width) & 7; + png_bytep rp = png_ptr->row_buf + row_info->rowbytes; + + switch (row_info->bit_depth) + { + case 1: + { + /* in this case, all bytes must be 0 so we don't need + * to unpack the pixels except for the rightmost one. + */ + for (; rp > png_ptr->row_buf; rp--) + { + if (*rp >> padding != 0) + png_ptr->num_palette_max = 1; + padding = 0; + } + + break; + } + + case 2: + { + for (; rp > png_ptr->row_buf; rp--) + { + int i = ((*rp >> padding) & 0x03); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + i = (((*rp >> padding) >> 2) & 0x03); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + i = (((*rp >> padding) >> 4) & 0x03); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + i = (((*rp >> padding) >> 6) & 0x03); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + padding = 0; + } + + break; + } + + case 4: + { + for (; rp > png_ptr->row_buf; rp--) + { + int i = ((*rp >> padding) & 0x0f); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + i = (((*rp >> padding) >> 4) & 0x0f); + + if (i > png_ptr->num_palette_max) + png_ptr->num_palette_max = i; + + padding = 0; + } + + break; + } + + case 8: + { + for (; rp > png_ptr->row_buf; rp--) + { + if (*rp > png_ptr->num_palette_max) + png_ptr->num_palette_max = (int) *rp; + } + + break; + } + + default: + break; + } + } +} +#endif /* PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED */ + #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \ defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED Index: dll/3rdparty/libpng/pngwrite.c =================================================================== --- dll/3rdparty/libpng/pngwrite.c (revision 56925) +++ dll/3rdparty/libpng/pngwrite.c (working copy) @@ -1,8 +1,8 @@ /* pngwrite.c - general routines to write a PNG file * - * Last changed in libpng 1.5.7 [December 15, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.11 [June 14, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -305,6 +305,11 @@ if (!(png_ptr->mode & PNG_HAVE_IDAT)) png_error(png_ptr, "No IDATs written into file"); +#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED + if (png_ptr->num_palette_max > png_ptr->num_palette) + png_benign_error(png_ptr, "Wrote palette index exceeding num_palette"); +#endif + /* See if user wants us to write information chunks */ if (info_ptr != NULL) { @@ -798,6 +803,14 @@ } #endif +/* Added at libpng-1.5.10 */ +#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED + /* Check for out-of-range palette index */ + if (row_info.color_type == PNG_COLOR_TYPE_PALETTE && + png_ptr->num_palette_max >= 0) + png_do_check_palette_indexes(png_ptr, &row_info); +#endif + /* Find a filter if necessary, filter the row and write it out. */ png_write_find_filter(png_ptr, &row_info); Index: dll/3rdparty/libpng/pngwutil.c =================================================================== --- dll/3rdparty/libpng/pngwutil.c (revision 56925) +++ dll/3rdparty/libpng/pngwutil.c (working copy) @@ -1,8 +1,8 @@ /* pngwutil.c - utilities to write a PNG file * - * Last changed in libpng 1.5.6 [November 3, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson + * Last changed in libpng 1.5.10 [March 8, 2012] + * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -569,14 +569,15 @@ /* Ship the compressed text out via chunk writes */ static void /* PRIVATE */ -png_write_compressed_data_out(png_structp png_ptr, compression_state *comp) +png_write_compressed_data_out(png_structp png_ptr, compression_state *comp, + png_size_t data_len) { int i; /* Handle the no-compression case */ if (comp->input) { - png_write_chunk_data(png_ptr, comp->input, comp->input_len); + png_write_chunk_data(png_ptr, comp->input, data_len); return; } @@ -585,7 +586,7 @@ /* The zbuf_size test is because the code below doesn't work if zbuf_size is * '1'; simply skip it to avoid memory overwrite. */ - if (comp->input_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1) + if (data_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1) { unsigned int z_cmf; /* zlib compression method and flags */ @@ -1164,8 +1165,7 @@ if (profile_len) { - comp.input_len = profile_len; - png_write_compressed_data_out(png_ptr, &comp); + png_write_compressed_data_out(png_ptr, &comp, profile_len); } png_write_chunk_end(png_ptr); @@ -1735,8 +1735,7 @@ png_write_chunk_data(png_ptr, &buf, (png_size_t)1); /* Write the compressed data */ - comp.input_len = text_len; - png_write_compressed_data_out(png_ptr, &comp); + png_write_compressed_data_out(png_ptr, &comp, text_len); /* Close the chunk */ png_write_chunk_end(png_ptr); @@ -1827,7 +1826,7 @@ png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf), (png_size_t)(lang_key_len + 1)); - png_write_compressed_data_out(png_ptr, &comp); + png_write_compressed_data_out(png_ptr, &comp, text_len); png_write_chunk_end(png_ptr); Index: include/reactos/libs/libpng/png.h =================================================================== --- include/reactos/libs/libpng/png.h (revision 56925) +++ include/reactos/libs/libpng/png.h (working copy) @@ -1,7 +1,7 @@ /* png.h - header file for PNG reference library * - * libpng version 1.5.9 - February 18, 2012 + * libpng version 1.5.12 - July 11, 2012 * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) @@ -11,7 +11,7 @@ * Authors and maintainers: * libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat * libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger - * libpng versions 0.97, January 1998, through 1.5.9 - February 18, 2012: Glenn + * libpng versions 0.97, January 1998, through 1.5.12 - July 11, 2012: Glenn * See also "Contributing Authors", below. * * Note about libpng version numbers: @@ -172,6 +172,12 @@ * 1.5.9beta01-02 15 10509 15.so.15.9[.0] * 1.5.9rc01 15 10509 15.so.15.9[.0] * 1.5.9 15 10509 15.so.15.9[.0] + * 1.5.10beta01-05 15 10510 15.so.15.10[.0] + * 1.5.10 15 10510 15.so.15.10[.0] + * 1.5.11beta01 15 10511 15.so.15.11[.0] + * 1.5.11rc01-05 15 10511 15.so.15.11[.0] + * 1.5.11 15 10511 15.so.15.11[.0] + * 1.5.12 15 10512 15.so.15.12[.0] * * Henceforth the source version will match the shared-library major * and minor numbers; the shared-library major version number will be @@ -181,7 +187,7 @@ * to the source version x.y.z (leading zeros in y and z). Beta versions * were given the previous public release number plus a letter, until * version 1.0.6j; from then on they were given the upcoming public - * release number plus "betaNN" or "rcN". + * release number plus "betaNN" or "rcNN". * * Binary incompatibility exists only when applications make direct access * to the info_ptr or png_ptr members through png.h, and the compiled @@ -203,7 +209,7 @@ * * This code is released under the libpng license. * - * libpng versions 1.2.6, August 15, 2004, through 1.5.9, February 18, 2012, are + * libpng versions 1.2.6, August 15, 2004, through 1.5.12, July 11, 2012, are * Copyright (c) 2004, 2006-2012 Glenn Randers-Pehrson, and are * distributed according to the same disclaimer and license as libpng-1.2.5 * with the following individual added to the list of Contributing Authors: @@ -315,13 +321,13 @@ * Y2K compliance in libpng: * ========================= * - * February 18, 2012 + * July 11, 2012 * * Since the PNG Development group is an ad-hoc body, we can't make * an official declaration. * * This is your unofficial assurance that libpng from version 0.71 and - * upward through 1.5.9 are Y2K compliant. It is my belief that + * upward through 1.5.12 are Y2K compliant. It is my belief that * earlier versions were also Y2K compliant. * * Libpng only has two year fields. One is a 2-byte unsigned integer @@ -332,7 +338,8 @@ * "png_uint_16 year" in png_time_struct. * * The string is - * "png_char time_buffer" in png_struct + * "char time_buffer[29]" in png_struct. This will be no + * longer used in libpng-1.6.0 and will be removed from libpng-1.7.0. * * There are seven time-related functions: * png.c: png_convert_to_rfc_1123() in png.c @@ -379,9 +386,9 @@ */ /* Version information for png.h - this should match the version in png.c */ -#define PNG_LIBPNG_VER_STRING "1.5.9" +#define PNG_LIBPNG_VER_STRING "1.5.12" #define PNG_HEADER_VERSION_STRING \ - " libpng version 1.5.9 - February 18, 2012\n" + " libpng version 1.5.12 - July 11, 2012\n" #define PNG_LIBPNG_VER_SONUM 15 #define PNG_LIBPNG_VER_DLLNUM 15 @@ -389,7 +396,7 @@ /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */ #define PNG_LIBPNG_VER_MAJOR 1 #define PNG_LIBPNG_VER_MINOR 5 -#define PNG_LIBPNG_VER_RELEASE 9 +#define PNG_LIBPNG_VER_RELEASE 12 /* This should match the numeric part of the final component of * PNG_LIBPNG_VER_STRING, omitting any leading zero: @@ -412,7 +419,7 @@ #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with PNG_LIBPNG_BUILD_PRIVATE */ -#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_BETA +#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE /* Careful here. At one time, Guy wanted to use 082, but that would be octal. * We must not include leading zeros. @@ -420,7 +427,7 @@ * version 1.0.0 was mis-numbered 100 instead of 10000). From * version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release */ -#define PNG_LIBPNG_VER 10509 /* 1.5.9 */ +#define PNG_LIBPNG_VER 10512 /* 1.5.12 */ /* Library configuration: these options cannot be changed after * the library has been built. @@ -542,7 +549,7 @@ /* This triggers a compiler error in png.c, if png.c and png.h * do not agree upon the version number. */ -typedef char* png_libpng_version_1_5_9; +typedef char* png_libpng_version_1_5_12; /* Three color definitions. The order of the red, green, and blue, (and the * exact size) is not important, although the size of the fields need to @@ -2637,6 +2644,12 @@ : (png_int_32)png_get_uint_32(buf))) #endif +#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \ + defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED) +PNG_EXPORT(234, void, png_set_check_for_invalid_index, (png_structp png_ptr, + int allowed)); +#endif + /* Maintainer: Put new public prototypes here ^, in libpng.3, and project * defs */ @@ -2646,7 +2659,7 @@ * scripts/symbols.def as well. */ #ifdef PNG_EXPORT_LAST_ORDINAL - PNG_EXPORT_LAST_ORDINAL(233); + PNG_EXPORT_LAST_ORDINAL(234); #endif #ifdef __cplusplus Index: include/reactos/libs/libpng/pngconf.h =================================================================== --- include/reactos/libs/libpng/pngconf.h (revision 56925) +++ include/reactos/libs/libpng/pngconf.h (working copy) @@ -1,7 +1,7 @@ /* pngconf.h - machine configurable file for libpng * - * libpng version 1.5.9 - February 18, 2012 + * libpng version 1.5.12 - July 11, 2012 * * Copyright (c) 1998-2012 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) @@ -25,7 +25,7 @@ #ifndef PNG_BUILDING_SYMBOL_TABLE /* PNG_NO_LIMITS_H may be used to turn off the use of the standard C * definition file for machine specific limits, this may impact the - * correctness of the definitons below (see uses of INT_MAX). + * correctness of the definitions below (see uses of INT_MAX). */ # ifndef PNG_NO_LIMITS_H # include @@ -51,8 +51,8 @@ /* This controls optimization of the reading of 16 and 32 bit values * from PNG files. It can be set on a per-app-file basis - it - * just changes whether a macro is used to the function is called. - * The library builder sets the default, if read functions are not + * just changes whether a macro is used when the function is called. + * The library builder sets the default; if read functions are not * built into the library the macro implementation is forced on. */ #ifndef PNG_READ_INT_FUNCTIONS_SUPPORTED Index: include/reactos/libs/libpng/pnglibconf.h =================================================================== --- include/reactos/libs/libpng/pnglibconf.h (revision 56925) +++ include/reactos/libs/libpng/pnglibconf.h (working copy) @@ -3,9 +3,9 @@ /* pnglibconf.h - library build configuration */ -/* libpng version 1.5.4 - last changed on June 22, 2011 */ +/* Libpng 1.5.12 - July 11, 2012 */ -/* Copyright (c) 1998-2011 Glenn Randers-Pehrson */ +/* Copyright (c) 1998-2012 Glenn Randers-Pehrson */ /* This code is released under the libpng license. */ /* For conditions of distribution and use, see the disclaimer */ @@ -31,10 +31,6 @@ #define PNG_QUANTIZE_GREEN_BITS 5 #define PNG_QUANTIZE_RED_BITS 5 #define PNG_sCAL_PRECISION 5 -#define PNG_USER_CHUNK_CACHE_MAX 0 -#define PNG_USER_CHUNK_MALLOC_MAX 0 -#define PNG_USER_HEIGHT_MAX 1000000 -#define PNG_USER_WIDTH_MAX 1000000 #define PNG_WEIGHT_SHIFT 8 #define PNG_ZBUF_SIZE 8192 /* end of settings */ @@ -45,6 +41,7 @@ #define PNG_bKGD_SUPPORTED #define PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED #define PNG_CHECK_cHRM_SUPPORTED +#define PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED #define PNG_cHRM_SUPPORTED #define PNG_CONSOLE_IO_SUPPORTED #define PNG_CONVERT_tIME_SUPPORTED @@ -74,6 +71,7 @@ #define PNG_READ_BACKGROUND_SUPPORTED #define PNG_READ_BGR_SUPPORTED #define PNG_READ_bKGD_SUPPORTED +#define PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED #define PNG_READ_cHRM_SUPPORTED #define PNG_READ_COMPOSITE_NODIV_SUPPORTED #define PNG_READ_COMPRESSED_TEXT_SUPPORTED @@ -145,6 +143,7 @@ #define PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED #define PNG_WRITE_BGR_SUPPORTED #define PNG_WRITE_bKGD_SUPPORTED +#define PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED #define PNG_WRITE_cHRM_SUPPORTED #define PNG_WRITE_COMPRESSED_TEXT_SUPPORTED #define PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED