type
 TDesktopCanvas = class(TCanvas)
 private
   DC : hDC;
   function     GetWidth:Integer;
   function     GetHeight:Integer;
 public
   constructor  Create;
   destructor   Destroy; override;
 published
   property Width: Integer read GetWidth;
   property Height: Integer read GetHeight;
 end;

function TDesktopCanvas.GetWidth:Integer;
begin
 Result:=GetDeviceCaps(Handle,HORZRES);
end;

function TDesktopCanvas.GetHeight:Integer;
begin
 Result:=GetDeviceCaps(Handle,VERTRES);
end;

constructor TDesktopCanvas.Create;
begin
 inherited Create;
 DC := GetDC(GetDesktopWindow);
 Handle := DC;
end;

destructor TDesktopCanvas.Destroy;
begin
 ReleaseDC(Handle, DC);
 inherited Destroy;
end;

Procedure SaveScreen(Const p_strFileName:String);
Var
 d:TDesktop
 b:TBitmap;
Begin
 b:=TBitmap.Create;
 d:=TDesktopCanvas.Create(Nil);
 b.Width:=d.Width;
 b.Height:=d.Height;
 d.CopyRect(Rect(0,0,d.Width,d.Height),b.Canvas,Rect(0,0,d.Width,d.Height));
 d.Free;
 b.SaveToFile(p_strFileName);
 b.Free;
End;