uses WinTypes, WinProcs, Forms, Controls, Classes, Graphics;

function CaptureScreenRect( ARect: TRect ): TBitmap;

var

ScreenDC: HDC;

begin

Result := TBitmap.Create;

with Result, ARect do

begin

Width := Right - Left;

Height := Bottom - Top;

ScreenDC := GetDC( 0 );

try

BitBlt( Canvas.Handle, 0, 0, Width, Height, ScreenDC,

Left, Top, SRCCOPY );

finally

ReleaseDC( 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.

Unit

Types

Delphi syntax:

type

TRect = packed record

case Integer of

0: (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 instance

HDC 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;

interface

uses 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;

{==============================================================================}

var

ScreenDC: HDC;

begin

Result := TBitmap.Create;

with Result, ARect do

begin

Width := Right - Left;

Height := Bottom - Top;

ScreenDC := GetDC( 0 );

try

BitBlt( Canvas.Handle, 0, 0, Width, Height, ScreenDC,

Left, Top, SRCCOPY );

finally

ReleaseDC( 0, ScreenDC );

end;

end;

end;

{==============================================================================}

{ Use this to capture the entire screen... }

function CaptureScreen: TBitmap;

{==============================================================================}

begin

with Screen do

Result := 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;

{==============================================================================}

begin

with Control, Control.ClientOrigin do

Result := CaptureScreenRect( Bounds( X, Y, ClientWidth,

ClientHeight ));

end;

{==============================================================================}

{ Use this to capture an entire form or control... }

function CaptureControlImage( Control: TControl ): TBitmap;

{==============================================================================}

begin

with Control do

if Parent = nil then

Result := CaptureScreenRect( Bounds( Left, Top, Width,

Height ))

else

with Parent.ClientToScreen( Point( Left, Top )) do

Result := 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;

{==============================================================================}

var

R: TRect;

begin

GetWindowRect(Wnd, R);

Result := CaptureScreenRect(R);

end;

end.