关于抓图的问题?

Question

以下这段代码怎么抓不了图呀?麻烦帮改一下,谢了~!
procedure TForm1.CaptureScreen;
var
    img : TBitmap;
    scr : TCanvas;
    dc  : HDC;
begin
     img:= TBitmap.Create;
     image1.Width:=screen.Width;
     image1.Height:=screen.Height;
     dc:=GetDC(0);
     scr:=TCanvas.Create;
     scr.Handle:=dc;
     img.Canvas.CopyRect(Rect(0,0,screen.Width,screen.Height),
              scr,Rect(0,0,Screen.Width,Screen.Height));
     scr.Free;
     releasedc(0,dc);
     image1.Picture.Bitmap:=img;
     image1.Width:=img.Width;
     image1.Height:=img.Height;
     img.Free;
                end;

Answer 1

procedure TForm1.CaptureScreen;
var
    img : TBitmap;
    scr : TCanvas;
    dc  : HDC;
begin
     img:= TBitmap.Create;
     img.Width := screen.Width;
     img.Height := screen.Height;
     image1.Width:=screen.Width;
     image1.Height:=screen.Height;
     dc:=GetDC(0);
     scr:=TCanvas.Create;
     scr.Handle:=dc;
     img.Canvas.CopyRect(Rect(0,0,screen.Width,screen.Height),
              scr,Rect(0,0,Screen.Width,Screen.Height));
     scr.Free;
     releasedc(0,dc);
//     image1.Picture.Bitmap:=img;
     image1.Picture.Bitmap.Assign(img);
     image1.Width:=img.Width;
     image1.Height:=img.Height;
     img.Free;
                end;我没调试过，你看行不行

Answer 2

var
    img : TBitmap;
    scr : TCanvas;
    dc  : HDC;
begin
     img:= TBitmap.Create;
     img.Width := screen.Width;
     img.Height := screen.Height;
     image1.Width:=screen.Width;
     image1.Height:=screen.Height;
     dc:=GetDC(0);
     scr:=TCanvas.Create;
     scr.Handle:=dc;
     img.Canvas.CopyRect(Rect(0,0,screen.Width,screen.Height),
              scr,Rect(0,0,Screen.Width,Screen.Height));
     scr.Free;
     releasedc(0,dc);
     //image1.Picture.Bitmap:=img;
     image1.Picture.Bitmap.Assign(img);
     image1.Width:=img.Width;
     image1.Height:=img.Height;
     img.Free;
     image1.picture:=nil//把原来的图片删除掉避免很多图片重复!           end;