Скачал от сюда http://sourceforge.net/projects/libpng/files/ LibPNG но совершенно не понимаю как добиться адекватного отображения альфа прозрачности | Код |
void PNGAPI user_error_fn(png_structp png, png_const_charp sz) { }
void PNGAPI user_warning_fn(png_structp png, png_const_charp sz) { }
HBITMAP LoadBitmapPNG(char *szFile)
{
HBITMAP hbm = NULL;
bool retVal = false;
int size = 0;
// check the header first
FILE *fp = fopen(szFile, "rb");
if (!fp)
return false;
BYTE header[8];
fread(header, 1, 8, fp);
fseek(fp, 0, SEEK_END);
size = ftell(fp);
fclose(fp);
if (png_sig_cmp(header, 0, 8))
return false;
// now allocate stuff
png_structp png_ptr =
png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, user_error_fn, user_warning_fn);
if (!png_ptr)
return false;
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 false;
}
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 false;
}
fp = fopen(szFile, "rb");
if (fp)
{
png_init_io(png_ptr, fp);
// should really use png_set_rows() to allocate space first, rather than doubling up
png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_EXPAND | PNG_TRANSFORM_BGR | PNG_TRANSFORM_PACKING, NULL);
fclose(fp);
png_bytep* row_pointers = png_get_rows(png_ptr, info_ptr);//new png_bytep[info_ptr->height];
// now for a tonne of ugly DIB setup crap
int width = info_ptr->width;
int height = info_ptr->height;
int bpp = info_ptr->channels * 8;
int memWidth = (width * (bpp >> 3) + 3) & ~3;
LPBITMAPINFO lpbi = (LPBITMAPINFO) new char[sizeof(BITMAPINFOHEADER) + (256 * sizeof(RGBQUAD))];
// create a greyscale palette
for (int a_i = 0; a_i < 256; a_i++)
{
lpbi->bmiColors[a_i].rgbRed = (BYTE)a_i;
lpbi->bmiColors[a_i].rgbGreen = (BYTE)a_i;
lpbi->bmiColors[a_i].rgbBlue = (BYTE)a_i;
lpbi->bmiColors[a_i].rgbReserved = 0;
}
lpbi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
lpbi->bmiHeader.biWidth = width;
lpbi->bmiHeader.biHeight = -height; // must be negative for top down
lpbi->bmiHeader.biPlanes = 1;
lpbi->bmiHeader.biBitCount = bpp;
lpbi->bmiHeader.biCompression = BI_RGB;
lpbi->bmiHeader.biSizeImage = memWidth * height;
lpbi->bmiHeader.biXPelsPerMeter = 0;
lpbi->bmiHeader.biYPelsPerMeter = 0;
lpbi->bmiHeader.biClrUsed = 0;
lpbi->bmiHeader.biClrImportant = 0;
BYTE * pixelData;
hbm = CreateDIBSection(NULL, lpbi, DIB_RGB_COLORS, (void **)&pixelData, NULL, 0 );
if (hbm && pixelData)
{
// now copy the rows
for (int i = 0; i < height; i++)
memcpy(pixelData + memWidth * i, row_pointers[i], width * info_ptr->channels);
}
delete (char*) lpbi;
}
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return hbm;
}
void SetSplashImage(HWND hwndSplash, HBITMAP hbmpSplash)
{
// get the size of the bitmap
BITMAP bm;
GetObject(hbmpSplash, sizeof(bm), &bm);
SIZE sizeSplash = { bm.bmWidth, bm.bmHeight };
// get the primary monitor's info
POINT ptZero = { 0 };
HMONITOR hmonPrimary = MonitorFromPoint(ptZero, MONITOR_DEFAULTTOPRIMARY);
MONITORINFO monitorinfo = { 0 };
monitorinfo.cbSize = sizeof(monitorinfo);
GetMonitorInfo(hmonPrimary, &monitorinfo);
// center the splash screen in the middle of the primary work area
const RECT & rcWork = monitorinfo.rcWork;
POINT ptOrigin;
ptOrigin.x = rcWork.left + (rcWork.right - rcWork.left - sizeSplash.cx) / 2;
ptOrigin.y = rcWork.top + (rcWork.bottom - rcWork.top - sizeSplash.cy) / 2;
// create a memory DC holding the splash bitmap
HDC hdcScreen = GetDC(NULL);
HDC hdcMem = CreateCompatibleDC(hdcScreen);
HBITMAP hbmpOld = (HBITMAP) SelectObject(hdcMem, hbmpSplash);
// use the source image's alpha channel for blending
BLENDFUNCTION blend = { 0 };
blend.BlendOp = AC_SRC_OVER;
blend.SourceConstantAlpha = 255;
blend.AlphaFormat = AC_SRC_ALPHA;
// paint the window (in the right location) with the alpha-blended bitmap
UpdateLayeredWindow(hwndSplash, hdcScreen, &ptOrigin, &sizeSplash,
hdcMem, &ptZero, RGB(0, 0, 0), &blend, ULW_ALPHA);
// delete temporary objects
SelectObject(hdcMem, hbmpOld);
DeleteDC(hdcMem);
ReleaseDC(NULL, hdcScreen);
}
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