Delphi中BitBlt函数实现屏幕对象抓图

 uses WinTypes, WinProcs, Forms, Controls, Classes, Graphics;function CaptureScreenRect( ARect: TRect ): TBitmap;varScreenDC: HDC;beginResult := TBitmap.Create;with Result, ARect dobeginWidth := Right - Left;Height := Bottom - Top;ScreenDC := GetDC( 0 );tryBitBlt( Canvas.Handle, 0, 0, Width, Height, ScreenDC,Left, Top, SRCCOPY );finallyReleaseDC( 0, ScreenDC );end;end;end;思路是这样的parameter 是一个 TRect， 也就是一个 4 方形，你可以设定，是这样的TRect defines a rectangle.UnitTypesDelphi syntax:typeTRect = packed recordcase Integer of0: (Left, Top, Right, Bottom: Integer);1: (TopLeft, BottomRight: TPoint);end;返回一个 Bitmap 也就是图像拉创建一个新的 bitmap instanceHDC 是一个 device context (DC)，也就可以利用 BitBlt 把windows 图像转到 bitmap 里了。完整代码在这里，朋友可以直接调用unit ScrnCap;interfaceuses WinTypes, WinProcs, Forms, Controls, Classes, Graphics;function CaptureScreenRect( ARect: TRect ): TBitmap;function CaptureScreen: TBitmap;function CaptureClientImage( Control: TControl ): TBitmap;function CaptureControlImage( Control: TControl ): TBitmap;function CaptureWindowImage( Wnd: HWND ): TBitmap;implementation{==============================================================================}{ Use this to capture a rectangle on the screen... }function CaptureScreenRect( ARect: TRect ): TBitmap;{==============================================================================}varScreenDC: HDC;beginResult := TBitmap.Create;with Result, ARect dobeginWidth := Right - Left;Height := Bottom - Top;ScreenDC := GetDC( 0 );tryBitBlt( Canvas.Handle, 0, 0, Width, Height, ScreenDC,Left, Top, SRCCOPY );finallyReleaseDC( 0, ScreenDC );end;end;end;{==============================================================================}{ Use this to capture the entire screen... }function CaptureScreen: TBitmap;{==============================================================================}beginwith Screen doResult := CaptureScreenRect( Rect( 0, 0, Width, Height ));end;{==============================================================================}{ Use this to capture just the client area of a form or control... }function CaptureClientImage( Control: TControl ): TBitmap;{==============================================================================}beginwith Control, Control.ClientOrigin doResult := CaptureScreenRect( Bounds( X, Y, ClientWidth,ClientHeight ));end;{==============================================================================}{ Use this to capture an entire form or control... }function CaptureControlImage( Control: TControl ): TBitmap;{==============================================================================}beginwith Control doif Parent = nil thenResult := CaptureScreenRect( Bounds( Left, Top, Width,Height ))elsewith Parent.ClientToScreen( Point( Left, Top )) doResult := CaptureScreenRect( Bounds( X, Y, Width,Height ));end;{==============================================================================}{ Use this to capture an entire form or control paased as an API hWnd... }function CaptureWindowImage( Wnd: HWND ): TBitmap;{==============================================================================}varR: TRect;beginGetWindowRect(Wnd, R);Result := CaptureScreenRect(R);end;end.