DrawTextA Works Abnormally

void OnPaint(HDC hdc, const RECT* prc, HFONT hf)

{

	char szBuffer[100];

	WCHAR wszBuffer[100];

	// "你好世界" encoded with GBK

	const char szTestText[] = {196, 227, 186, 195, 202, 192, 189, 231, 0};

	// "你好世界" encoded with UTF16

	const WCHAR wszTestText[] = {20320, 22909, 19990, 30028, 0};

	HFONT hfOld = (HFONT)SelectObject(hdc, hf);

	int x, y;

	SIZE sz;

	RECT rc = *prc;

	SetBkColor(hdc, g_rgbBackground);

	SetTextColor(hdc, g_rgbText);

	if(g_bOpaque)

	{

		SetBkMode(hdc, OPAQUE);

	}

	else

	{

		SetBkMode(hdc, TRANSPARENT);

	}

	x = prc->left;

	y = prc->top;

	wsprintfA(szBuffer, "TextOutA Test: %s", szTestText);

	TextOutA(hdc, x, y, szBuffer, strlen(szBuffer));

	GetTextExtentPoint32A(hdc, szBuffer, strlen(szBuffer), &sz);

	y += sz.cy;

	wsprintfW(wszBuffer, L"TextOutW Test: %s", wszTestText);

	TextOutW(hdc, x, y, wszBuffer, wcslen(wszBuffer));

	GetTextExtentPoint32W(hdc, wszBuffer, wcslen(wszBuffer), &sz);

	y += sz.cy;

	rc.top = y;

	wsprintfA(szBuffer, "DrawTextA Test: %s", szTestText);

	DrawTextA(hdc, szBuffer, -1, &rc, DT_SINGLELINE);

	GetTextExtentPoint32A(hdc, szBuffer, strlen(szBuffer), &sz);

	y += sz.cy;

	rc.top = y;

	wsprintfW(wszBuffer, L"DrawTextW Test: %s", wszTestText);

	DrawTextW(hdc, wszBuffer, -1, &rc, DT_SINGLELINE);

	SelectObject(hdc, hfOld);

}