Delphi-PRAXiS - Delphi transparentes Bild über Bild ausgeben

hi!

Habe erst letzthin folgende Funktion gebraucht.
Vielleicht kannst du noch Trys und Excepts an der richtigen Stelle einsetzen.
Delphi-Quellcode:
			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;