Скриншот на WinApi

uses ..., JPEG;
...
var BMP: TBitmap;
    JPG: TJpegImage;
begin
 BMP := TBitmap.Create;
 JPG := TJpegImage.Create;
 BMP.LoadFromFile('c:\tmp\111.bmp');
 JPG.Assign(BMP);
 JPG.SaveToFile('c:\tmp\111.jpg');
 BMP.Free;
 JPG.Free;
end;

procedure ScreenShot;
var c: TCanvas;
    r: TRect;
    BMP: TBitmap;
    JPG: TJpegImage;
begin
 BMP := TBitmap.Create;
 JPG := TJpegImage.Create;
 c := TCanvas.Create;
 c.Handle := GetWindowDC(GetDesktopWindow);
 try
   r := Rect(0, 0, Screen.Width, Screen.Height);
   BMP.Width := Screen.Width;
   BMP.Height := Screen.Height;
   BMP.Canvas.CopyRect(r, c, r);
   JPG.Assign(BMP);
   JPG.SaveToFile('c:\tmp\111.jpg');
 finally
   ReleaseDC(0, c.Handle);
   c.Free;
   BMP.Free;
   JPG.Free;
 end;
end;

  MonInfo.cbSize := SizeOf(MonInfo);
  GetMonitorInfo(MonitorFromWindow(Handle, MONITOR_DEFAULTTONEAREST), @MonInfo);
  ShowMessage(Format('Current resolution: %dx%d',
              [MonInfo.rcMonitor.Right - MonInfo.rcMonitor.Left,
               MonInfo.rcMonitor.Bottom - MonInfo.rcMonitor.Top]));

showmessage(IntTostr(Screen.Width) + Inttostr(Screen.Height));