Konvertierung Pixel nach Rect oder Denkfehler?

[EWeiss]

Beispiel.
Copy\Paste aus meiner SkinEngine.

Delphi-Quellcode:

  DC := GetDC(FOwner);
  hDCBack := CreateCompatibleDC(DC);

  GetClientRect(Handle, rc);

  GetWindowRect(Handle, rw);
  lp.x := rw.Left;
  lp.y := rw.Top;
  ScreenToClient(FOwner, lp);

  SelectObject(hDCBack, SkinEngine.GetBackBitmap(FOwner));
    BitBlt(DC, lp.x, lp.y, rc.Right, rc.Bottom, hDCBack, lp.x,
      lp.y, SRCCOPY);
  DeleteDC(hDCBack);
  ReleaseDC(FOwner, DC);

gruss