如何抓取屏幕？？使占用内存最小，抓取速度最快？？可能要用的directx的知识。

Question

var
   hdcDesktop: HDC;
   bmpDesktop: TBitmap;
begin
   hdcDesktop := CreateDC('DISPLAY', '', '', Nil);
   bmpDesktop := TBitmap.Create;
   bmpDesktop.Handle := CreateCompatibleBitmap(hdcDesktop, Screen.Width, Screen.Height);
   bmpDesktop.SaveToFile('C:\Desktop.bmp');
   bmpDesktop.Free;
   DeleteDC(hdcDesktop);
end;

Answer 1

对不起，刚才是错的，现把源代码公布如下：
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;type
  TForm1 = class(TForm)
    ScrollBox1: TScrollBox;
    Bevel1: TBevel;
    Image1: TImage;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.DFM}procedure asdfa;
begin
   GetDC(0);
end;procedure TForm1.Button1Click(Sender: TObject);
var
   hDesktop: HBITMAP;
   bmpDesktop: TBitmap;
   hdcDesktop, hdcTemp: HDC;
begin
   hdcDesktop := CreateDC('DISPLAY', '', '', Nil);
   hdcTemp := CreateCompatibleDC(hdcDesktop);
   hDesktop := CreateCompatibleBitmap(hdcDesktop, Screen.Width, Screen.Height);
   SelectObject(hdcTemp, hDesktop);
   BitBlt(hdcTemp, 0, 0, Screen.Width, Screen.Height, hdcDesktop, 0, 0, SRCCOPY);
   //
   bmpDesktop := TBitmap.Create;
   bmpDesktop.Handle := hDesktop;
   Image1.Picture.Bitmap := bmpDesktop;
   bmpDesktop.Free;
   DeleteDC(hdcTemp);
   ReleaseDC(hDesktop, hdcDesktop);
end;end.