屏幕截图、窗口截图、指定区域截图

Use Jpeg

procedure TForm1.snapscreen(a,b,c,d:Integer);
var
  bmpscreen:Tbitmap;
  jpegscreen:Tjpegimage;
  FullscreenCanvas:TCanvas;
  dc:HDC;
  sourceRect, destRect: TRect;
begin
  try
  dc:=getdc(0);
  fullscreencanvas:=Tcanvas.Create;
  fullscreencanvas.Handle:=dc;
  bmpscreen:=Tbitmap.create;
  bmpscreen.Width :=c-a;
  bmpscreen.Height :=d-b;
  sourcerect:=rect(0,0,c-a ,d-b );
  destrect:= rect(a,b,c,d);
  bmpscreen.Canvas.CopyRect(sourcerect,fullscreenCanvas,destrect);
  jpegscreen:=Tjpegimage.Create ;
  jpegscreen.Assign (bmpscreen);
  jpegscreen.CompressionQuality:=100;
  jpegscreen.SaveToFile(ExtractFilePath(ParamStr(0))+'tmp.jpg');
  FullscreenCanvas.Free;
  bmpscreen.Free;
  jpegscreen.Free ;
  ReleaseDC(0, DC);
  except
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  snapscreen(self.Left,self.Top,Self.Left+self.Width,Self.Top+self.Height);
end;