VC++ Bitblt 로만 투명 효과 구현

 

 

BOOL TransparentMyBlt( HDC hdcDest, int nXDest, int nYDest, int nWidth, 
   int nHeight, HDC hdcSrc, int nXOriginSrc, int nYOriginSrc, int nXSrc, int nYSrc,
   COLORREF colorTransparent)
{
 CDC dc, memDC, maskDC;//, tempDC;
 dc.Attach( hdcDest );
 maskDC.CreateCompatibleDC(&dc);
 CBitmap maskBitmap;
 
 //add these to store return of SelectObject() calls
 CBitmap* pOldMemBmp = NULL;
 CBitmap* pOldMaskBmp = NULL;
 
 memDC.CreateCompatibleDC(&dc);
 CBitmap bmpImage;
 bmpImage.CreateCompatibleBitmap( &dc, nWidth, nHeight );
 pOldMemBmp = memDC.SelectObject( &bmpImage );
 
 // Select and realize the palette
 /*
 if( dc.GetDeviceCaps(RASTERCAPS) & RC_PALETTE && hPal )
 {
  ::SelectPalette( dc, hPal, FALSE );
  dc.RealizePalette();
  
  ::SelectPalette( memDC, hPal, FALSE );
 }
 */
  
 //memDC.BitBlt( 0,0,nWidth, nHeight, hdcSrc, nXOriginSrc, nYOriginSrc, SRCCOPY );
 BitBlt(memDC.GetSafeHdc(), 0,0,nWidth, nHeight, hdcSrc, nXOriginSrc, nYOriginSrc, SRCCOPY );
 
 // Create monochrome bitmap for the mask
 maskBitmap.CreateBitmap( nWidth, nHeight, 1, 1, NULL );
 pOldMaskBmp = maskDC.SelectObject( &maskBitmap );
 memDC.SetBkColor( colorTransparent );
 
 // Create the mask from the memory DC
 maskDC.BitBlt( 0, 0, nWidth, nHeight, &memDC, 
  0, 0, SRCCOPY );
 
 // Set the background in memDC to black. Using SRCPAINT with black 
 // and any other color results in the other color, thus making 
 // black the transparent color
 memDC.SetBkColor(RGB(0,0,0));
 memDC.SetTextColor(RGB(255,255,255));
 memDC.BitBlt(0, 0, nWidth, nHeight, &maskDC, 0, 0, SRCAND);
 
 // Set the foreground to black. See comment above.
 dc.SetBkColor(RGB(255,255,255));
 dc.SetTextColor(RGB(0,0,0));
 dc.BitBlt(nXDest, nYDest, nWidth, nHeight, &maskDC, 0, 0, SRCAND);
 
 // Combine the foreground with the background
 dc.BitBlt(nXDest, nYDest, nWidth, nHeight, &memDC, 
  0, 0, SRCPAINT);
 
 if (pOldMaskBmp)
  maskDC.SelectObject( pOldMaskBmp );
 if (pOldMemBmp)
  memDC.SelectObject( pOldMemBmp );
 
 dc.Detach();
 return TRUE;
}