怎么取得桌面的图象

Question

c:=TBitmap.Create;
  c.Canvas.Handle:=GetDC(0);  d:=TBitmap.Create;
  d.Canvas.CopyRect(rect(0,0,self.ClientWidth,self.ClientHeight),c.Canvas,rect(left,top,left+clientwidth,top+clientheight));  ReleaseDC(0, c.handle);  d.SaveToFile('c:\xx.bmp');怎么d里面什么都没有？

Answer 1

procedure CopyCurrentDesktop(IncludeCur:Boolean);(为True时有鼠标指针，为Flase时没有鼠标指针)
var 
 DesktophWnd:hWnd;
 DesktopDC:hWnd;
 CursorhWnd:hWnd;
 CurPos:Tpoint;
 Rect:TRect; 
 Bitmap:TBitmap;
begin
 DesktophWnd := GetDesktopWindow();
 DesktopDC := GetDC(DesktophWnd);
 GetWindowRect(DesktophWnd, Rect);
 if IncludeCur then
  begin
   CursorhWnd:=GetCursor();            //捕获当前鼠标指针句柄
   GetCursorPos(CurPos);
  end;                  //获取当前鼠标指针的位置坐标
 Bitmap := TBitmap.Create;//生成一个Tbitmap类型的实例对象
 Bitmap.Width := Rect.Right-Rect.Left; 
 Bitmap.Height := Rect.Bottom-Rect.Top; 
 BitBlt(Bitmap.Canvas.Handle, 0, 0,
 Bitmap.Width, Bitmap.Height, DesktopDC, 0, 0, SRCCOPY);//在抓取到的位图对象上绘制鼠标
 if IncludeCur then
  DrawIcon(Bitmap.Canvas.Handle, CurPos.X, CurPos.Y, CursorhWnd);
 ReleaseDC(DesktophWnd, DesktopDC); 
 Bitmap.SaveToFile('C:\Desktop.bmp'); //使用类方法SaveToFile保存文件
 Bitmap.Free;
 ShowMessage('成功抓取屏幕并保存图像至C:\Desktop.bmp文件!');
end;

Answer 2

c.Canvas.Handle:=GetDC('DISPLAY');
或者是CreateDC('DISPLAY', ...);年代久远，记不清了。

Answer 3

unit Unit1;interfaceuses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, StdCtrls, Buttons, ExtCtrls;type
   TForm1 = class(TForm)
      Image1: TImage;
      BitBtn1: TBitBtn;
      procedure BitBtn1Click(Sender: TObject);
   private
      { Private declarations }
   public
      { Public declarations }
   end;var
   Form1: TForm1;implementation{$R *.dfm}procedure ScreenCapture(Bmp: TBitmap);
var
   DeskWnd: HWnd;
   DeskDC: HDC;
   DeskCv: TCanvas;
   R: TRect;
   W, H: Integer;
begin
   if Bmp = nil then Exit;
   DeskWnd := GetDesktopWindow;
   DeskDC := GetWindowDC(DeskWnd);
   DeskCv := TCanvas.Create;
   DeskCv.Handle := DeskDC;
   W := Screen.Width;
   H := Screen.Height;
   R := Bounds(0, 0, W, H);
   try
      Bmp.HandleType := bmDIB;
      Bmp.PixelFormat := pf24Bit;
      Bmp.Width := W;
      Bmp.Height := H;
      Bmp.Canvas.CopyMode := cmSrcCopy;
      Bmp.Canvas.CopyRect(R, DeskCv, R);
   finally
      DeskCv.Free;
      ReleaseDC(DeskWnd, DeskDC);
   end;
end; {Marco Lange}procedure TForm1.BitBtn1Click(Sender: TObject);
begin
   ScreenCapture(image1.Picture.Bitmap);
end;end.