捕捉整个桌面的图片

捕捉整个桌面的图片 但不捕捉自己这个窗体

procedure TForm2.Button3Click(Sender:
TObject);
var
  Bitmap:
Tbitmap;
  BitmapCanvas: TCanvas;
  dc:
HDC;
  DeskTopWidth,DeskTopHeight:Integer;
begin
  DeskTopWidth:= Screen.Width;
  DeskTopHeight:=Screen.Height;

Panel1.Width:=DeskTopWidth;
  Panel1.Height:=DeskTopHeight;

Hide;
  Sleep(200);
  Bitmap :=
TBitmap.Create;
  With Bitmap
do
  begin
    Width := DeskTopWidth;
    Height := DeskTopHeight;
    DC := GetDC(0);

BitmapCanvas :=
TCanvas.Create;
    BitmapCanvas.Handle :=
DC;

Canvas.CopyRect(Rect(0, 0,DeskTopWidth,
DeskTopHeight), BitmapCanvas,Rect(0, 0, DeskTopWidth,
DeskTopHeight));
    BitmapCanvas.Free;
    ReleaseDC(0,
DC);

Image1.Picture.Bitmap := Bitmap;
    Image1.Width := Width;
    Image1.Height :=
Height;
    Free;
  end;
  Show;
  SetForegroundWindow(Handle);

end;