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Delphi中BitBlt函数实现屏幕对象抓图

时间:2011/9/3 15:02:11 点击:

  核心提示:uses WinTypes, WinProcs, Forms, Controls, Classes, Graphics;function CaptureScreenRect( ARect: TRect...
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.

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