unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type 
  TForm1 =class (TForm)
    Button1: TButton;
    procedure Button1Click (Sender: TObject);
  end ;

var
  Form1: TForm1;

implementation

{$ R * .dfm}

// Capture full screen image and save it to: c: \ temp \ Screen.bmp
procedure TForm1.Button1Click (Sender: TObject);
var
  bit: TBitmap;
  DC: HDC;
  cvs: TCanvas;
begin
  bit: = TBitmap.Create;
  bit.SetSize (Screen.Width, Screen.Height);

  DC: = GetDC (0);
  cvs: = TCanvas.Create;
  cvs.Handle: = DC;

  bit.Canvas.CopyRect (Screen.DesktopRect, cvs, Screen.DesktopRect);
  bit.SaveToFile ('c: \ temp \ Screen.bmp');

  ReleaseDC (0, DC);
  cvs.Free;
  bit.Free;
end ;

end .