How to capture the Windows desktop to a form canvas

Problem/Question/Abstract:

How to capture the Windows desktop to a form canvas

Answer:

procedure TScrnFrm.GrabScreen;
var
  DeskTopDC: HDc;
  DeskTopCanvas: TCanvas;
  DeskTopRect: TRect;
begin
  DeskTopDC := GetWindowDC(GetDeskTopWindow);
  DeskTopCanvas := TCanvas.Create;
  DeskTopCanvas.Handle := DeskTopDC;
  DeskTopRect := Rect(0, 0, Screen.Width, Screen.Height);
  ScrnForm.Canvas.CopyRect(DeskTopRect, DeskTopCanvas, DeskTopRect);
  ReleaseDC(GetDeskTopWindow, DeskTopDC);
end;

Note: You may also have to play around with coordinates, depending on what you want to do. Also, if your form is already loaded and displayed, that is what you you will get, so you may want to do a hide and a show.