求救（100分）：如何窃取一端时间内，显示器上的变化，并把他保存为多媒体文件或电影文件

Question

求救：如何窃取一端时间内，显示器上的变化，并把他保存为多媒体文件或电影文件。
就象用摄影机摄显示屏的变化一样

Answer 1

用windows hook，截获刷新消息，只传输刷新部分

Answer 2

Directx抓图：unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  DXDraws, StdCtrls,DXClass, DirectX,RLEUnit;type
  TRGB16=TWordArray;
  PRGB16=^TRGB16;  TForm1 = class(TForm)
    DXDraw1: TDXDraw;
    DXTimer1: TDXTimer;
    Label1: TLabel;
    procedure DXDraw1InitializeSurface(Sender: TObject);
    procedure DXDraw1FinalizeSurface(Sender: TObject);    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormShow(Sender: TObject);
    procedure DXTimer1Timer(Sender: TObject; LagCount: Integer);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
const
  WW:Integer=640;   //抓屏宽度和高度
  HH:Integer=480;
var
  Form1: TForm1;
  FSurface:TDirectDrawSurface;
  ScrDC:HDC;
  i:Integer;
  mPos:TPoint;
  posX,posY:Integer;
  ImgBuf:PRGB16;procedure ProcImage(SrcImgBuf:Pointer;Count:integer);
implementation
uses
  unit2;
{$R *.DFM}procedure TForm1.DXDraw1InitializeSurface(Sender: TObject);
begin
//Create a offline surface
  FSurface:=TDirectDrawSurface.Create(DXDraw1.DDraw);
  FSurface.SetSize(WW,HH);
  FSurface.SystemMemory:=true;
  fsurface.Fill(0);
//get Screen DC
  ScrDC:=getDC(0);
end;procedure TForm1.DXDraw1FinalizeSurface(Sender: TObject);
begin
  FSurface.Free;
  FSurface:=nil;
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  ImgBuf:=GlobalAllocPtr(GPTR,WW*HH*2);  //16bitsend;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  DXTimer1.Enabled:=False;
  GlobalFreePtr(ImgBuf);
end;procedure TForm1.FormShow(Sender: TObject);
begin
DXTimer1.Enabled:=True;
end;procedure TForm1.DXTimer1Timer(Sender: TObject; LagCount: Integer);
var
//the structure of surface
  SurfaceDESC:TDDSurfaceDesc;
begin
  //GetCursorPos(mPos);
  mPos.x:=400;
  mPos.y:=300;
  //clear surface
  FSurface.Fill(0);
  // use hardware bitblt Image form ScreenDC to Surface
  BitBlt(FSurface.Canvas.Handle,0,0,WW,HH,ScrDC,mPos.x-WW div 2,mPos.y-HH div 2,SRCCOPY);
 // Free Surface DC Handel
  FSurface.Canvas.Release;{Get Image Data from Surface bits}
  if FSurface.Lock(SurfaceDESC)=true then
  begin
    ProcImage(SurfaceDesc.lpSurface,WW*HH*2);
    FSurface.UnLock;
  end
  else Beep;
  Caption:=Format('Current FPS: %d',[dxtimer1.FrameRate]);
end;procedure ProcImage(SrcImgBuf:Pointer;Count:integer);
begin
  Move(srcImgBuf^,ImgBuf^,Count);
  unit2.showImg(ImgBuf,Count);
end;
end.

Answer 3

必须用delphi吗？如果不是的话，我知道有flash cam可以实现。