Delphi图象截取编程示例(8)

(七)抓取图标（ICON）的窗体
创建一个新的Form3，保存为Capture3.pas。设置属性BorderIcons的四个属性为false.
BorderStyle设为bsNone,FormStyle设为fsStayOnTop.
一个私有变量：fDragging:Boolean; 两个公共变量:fRect:TRect,fBmp:TBitmap;

unit Capture3;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;

type
TForm3 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormMouseMove(Sender: TObject; Shift: TShiftState;
X, Y: Integer);
procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormActivate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
private
fDragging:Boolean;
public
fRect:TRect;
fBmp:TBitmap;
end;

var
Form3: TForm3;

implementation

{$R *.dfm}

//创建一个新的自定义光标CURSOR_2,放在Capture3.res资源
//文件中.是32*32的白色矩形边框，用来指示抓图的范围.
procedure TForm3.FormCreate(Sender: TObject);
var aDC:HDC ;
const crBox = -19;
begin
Screen.Cursors[crBox]:=LoadCursor(hInstance,''''CURSOR_2'''');
Cursor := crBox;
fBmp := TBitmap.Create ;
fBmp.Width := Screen.Width ;
fBmp.Height:= Screen.Height;
aDC := GetDC(0);
BitBlt(fBmp.Canvas.Handle,0,0,Screen.Width,Screen.Height,aDC,0,0,srcCopy);
ReleaseDC(0,aDC);
SetBounds(0,0,Screen.Width,Screen.Height);
end;

procedure TForm3.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if mbLeft = Button then begin
fDragging := true;
SetRect(fRect,X,Y,X 32,Y 32);
Canvas.DrawFocusRect(fRect);
end;
end;

procedure TForm3.FormMouseMove(Sender: TObject; Shift: TShiftState;
X, Y: Integer);
begin
if fDragging then begin
Canvas.DrawFocusRect(fRect);
fRect.Left := X ;
fRect.Top := Y ;
fRect.Right:= X 32;
fRect.Bottom:=Y 32;
Canvas.DrawFocusRect(fRect);
end;
end;

procedure TForm3.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
ModalResult:=mrOK;
end;

procedure TForm3.FormActivate(Sender: TObject);
const crHand=-18;
begin
Screen.Cursors[crHand]:=LoadCursor(hInstance,pChar(''''CURSOR_1''''));
Cursor:=crHand;
end;

procedure TForm3.FormDestroy(Sender: TObject);
begin
fBmp.Free;
Screen.Cursor := crDefault;
end;

procedure TForm3.FormPaint(Sender: TObject);
begin
Canvas.Draw(0,0,fBmp);
end;

end.

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