ASM Community

bool TransparentBltU(
HDC dcDest, // handle to Dest DC
int nXOriginDest, // x-coord of destination upper-left corner
int nYOriginDest, // y-coord of destination upper-left corner
int nWidthDest, // width of destination rectangle
int nHeightDest, // height of destination rectangle
HDC dcSrc, // handle to source DC
int nXOriginSrc, // x-coord of source upper-left corner
int nYOriginSrc, // y-coord of source upper-left corner
int nWidthSrc, // width of source rectangle
int nHeightSrc, // height of source rectangle
UINT crTransparent // color to make transparent
)
{
if (nWidthDest < 1) return false;
if (nWidthSrc < 1) return false;
if (nHeightDest < 1) return false;
if (nHeightSrc < 1) return false;

HDC dc = CreateCompatibleDC(NULL);
HBITMAP bitmap = CreateBitmap(nWidthSrc, nHeightSrc, 1,
GetDeviceCaps(dc, BITSPIXEL), NULL);

if (bitmap == NULL)
return false;

HBITMAP oldBitmap = (HBITMAP)SelectObject(dc, bitmap);

if (!BitBlt(dc, 0, 0, nWidthSrc, nHeightSrc, dcSrc,
nXOriginSrc, nYOriginSrc, SRCCOPY))
return false;

HDC maskDC = CreateCompatibleDC(NULL);
HBITMAP maskBitmap = CreateBitmap(nWidthSrc,
nHeightSrc, 1, 1, NULL);

if (maskBitmap == NULL)
return false;

HBITMAP oldMask = (HBITMAP)SelectObject(maskDC,
maskBitmap);

SetBkColor(maskDC, RGB(0,0,0));
SetTextColor(maskDC, RGB(255,255,255));
if (!BitBlt(maskDC, 0,0,nWidthSrc,nHeightSrc,NULL,
0,0,BLACKNESS))
return false;

SetBkColor(dc, crTransparent);
BitBlt(maskDC, 0,0,nWidthSrc,nHeightSrc,dc,0,0,SRCINVERT);

SetBkColor(dc, RGB(0,0,0));
SetTextColor(dc, RGB(255,255,255));
BitBlt(dc, 0,0,nWidthSrc,nHeightSrc,maskDC,0,0,SRCAND);

HDC newMaskDC = CreateCompatibleDC(NULL);
HBITMAP newMask;
newMask = CreateBitmap(nWidthDest, nHeightDest, 1,
GetDeviceCaps(newMaskDC, BITSPIXEL), NULL);

if (newMask == NULL)
{
SelectObject(dc, oldBitmap);
DeleteDC(dc);
SelectObject(maskDC, oldMask);
DeleteDC(maskDC);
DeleteDC(newMaskDC);
return false;
}

SetStretchBltMode(newMaskDC, COLORONCOLOR);
HBITMAP oldNewMask = (HBITMAP) SelectObject(newMaskDC,
newMask);
StretchBlt(newMaskDC, 0, 0, nWidthDest, nHeightDest,
maskDC, 0, 0, nWidthSrc, nHeightSrc, SRCCOPY);

SelectObject(maskDC, oldMask);
DeleteDC(maskDC);

HDC newImageDC = CreateCompatibleDC(NULL);
HBITMAP newImage = CreateBitmap(nWidthDest, nHeightDest,
1, GetDeviceCaps(newMaskDC, BITSPIXEL), NULL);

if (newImage == NULL)
{
SelectObject(dc, oldBitmap);
DeleteDC(dc);
DeleteDC(newMaskDC);
return false;
}

HBITMAP oldNewImage = (HBITMAP)SelectObject(newImageDC,
newImage);
StretchBlt(newImageDC, 0, 0, nWidthDest, nHeightDest,
dc, 0, 0, nWidthSrc, nHeightSrc, SRCCOPY);

SelectObject(dc, oldBitmap);
DeleteDC(dc);

BitBlt( dcDest, nXOriginDest, nYOriginDest, nWidthDest,
nHeightDest, newMaskDC, 0, 0, SRCAND);

BitBlt( dcDest, nXOriginDest, nYOriginDest, nWidthDest,
nHeightDest, newImageDC, 0, 0, SRCPAINT);

newImage = (HBITMAP)SelectObject(newImageDC, oldNewImage);
DeleteObject(newImage) ;
DeleteDC(newImageDC);
newMask = (HBITMAP)SelectObject(newMaskDC, oldNewMask);
DeleteObject(newMask) ;
DeleteDC(newMaskDC);
DeleteDC(dc) ;
DeleteObject(bitmap) ;

return true;
}