Bitblt und transparenz

[Delphi-Noobie]

ok hab ne Lösung gefunden sogar ohne Maskblt.

Code:

procedure DrawTransparentBitmap(DC: HDC; hBmp : HBITMAP ;
          xStart: integer; yStart : integer; cTransparentColor : COLORREF);
var
      bm: BITMAP;
      cColor: COLORREF;
      bmAndBack, bmAndObject, bmAndMem, bmSave: HBITMAP;
      bmBackOld, bmObjectOld, bmMemOld, bmSaveOld: HBITMAP;
      hdcMem, hdcBack, hdcObject, hdcTemp, hdcSave: HDC;
      ptSize: TPOINT;

begin
   hdcTemp := CreateCompatibleDC(dc);
   SelectObject(hdcTemp, hBmp); // Select the bitmap

   GetObject(hBmp, sizeof(BITMAP), @bm);
   ptSize.x := bm.bmWidth; // Get width of bitmap
   ptSize.y := bm.bmHeight; // Get height of bitmap
   DPtoLP(hdcTemp, ptSize, 1); // Convert from device
                                      // to logical points

   // Create some DCs to hold temporary data.
   hdcBack := CreateCompatibleDC(dc);
   hdcObject := CreateCompatibleDC(dc);
   hdcMem := CreateCompatibleDC(dc);
   hdcSave := CreateCompatibleDC(dc);

   // Create a bitmap for each DC. DCs are required for a number of
   // GDI functions.

   // Monochrome DC
   bmAndBack := CreateBitmap(ptSize.x, ptSize.y, 1, 1, nil);

   // Monochrome DC
   bmAndObject := CreateBitmap(ptSize.x, ptSize.y, 1, 1, nil);

   bmAndMem := CreateCompatibleBitmap(dc, ptSize.x, ptSize.y);
   bmSave := CreateCompatibleBitmap(dc, ptSize.x, ptSize.y);

   // Each DC must select a bitmap object to store pixel data.
   bmBackOld := SelectObject(hdcBack, bmAndBack);
   bmObjectOld := SelectObject(hdcObject, bmAndObject);
   bmMemOld := SelectObject(hdcMem, bmAndMem);
   bmSaveOld := SelectObject(hdcSave, bmSave);

   // Set proper mapping mode.
   SetMapMode(hdcTemp, GetMapMode(dc));

   // Save the bitmap sent here, because it will be overwritten.
   BitBlt(hdcSave, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCCOPY);

   // Set the background color of the source DC to the color.
   // contained in the parts of the bitmap that should be transparent
   cColor := SetBkColor(hdcTemp, cTransparentColor);

   // Create the object mask for the bitmap by performing a BitBlt
   // from the source bitmap to a monochrome bitmap.
   BitBlt(hdcObject, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0,
          SRCCOPY);

   // Set the background color of the source DC back to the original
   // color.
   SetBkColor(hdcTemp, cColor);

   // Create the inverse of the object mask.
   BitBlt(hdcBack, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0,
          NOTSRCCOPY);

   // Copy the background of the main DC to the destination.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, dc, xStart, yStart,
          SRCCOPY);

   // Mask out the places where the bitmap will be placed.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0, SRCAND);

   // Mask out the transparent colored pixels on the bitmap.
   BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcBack, 0, 0, SRCAND);

   // XOR the bitmap with the background on the destination DC.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCPAINT);

   // Copy the destination to the screen.
   BitBlt(dc, xStart, yStart, ptSize.x, ptSize.y, hdcMem, 0, 0,
          SRCCOPY);

   // Place the original bitmap back into the bitmap sent here.
   BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcSave, 0, 0, SRCCOPY);

   // Delete the memory bitmaps.
   DeleteObject(SelectObject(hdcBack, bmBackOld));
   DeleteObject(SelectObject(hdcObject, bmObjectOld));
   DeleteObject(SelectObject(hdcMem, bmMemOld));
   DeleteObject(SelectObject(hdcSave, bmSaveOld));

   // Delete the memory DCs.
   DeleteDC(hdcMem);
   DeleteDC(hdcBack);
   DeleteDC(hdcObject);
   DeleteDC(hdcSave);
   DeleteDC(hdcTemp);
end;

Gruß Delphi-Noobie