(六)區域抓圖窗體
創建一個新的Form1，保存為Capture1.pas。設置屬性BorderIcons的四個屬性為false.
BorderStyle設為bsNone,Cursor設為crCross,FormStyle設為fsStayOnTop.
添加一個私有變量：fDragging:Boolean;兩個公共變量:fRect:TRect,fBmp:TBitmap;
Form1的作用：在區域抓圖時創建，抓圖後消失.
unit Capture1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TForm1 = class(TForm)
PRocedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(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);
private
fDragging:Boolean;
public
fRect:TRect;
fBmp:TBitmap;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
var aDC:HDC; //設備描述表的句柄
begin
fBmp := TBitmap.Create ;
fBmp.Width := Screen.Width ;
fBmp.Height:= Screen.Height;
aDC := GetDC(0); //獲取一個窗口的設備描述表的句柄，0參數返回屏幕窗口設備描述表的句柄
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 TForm1.FormDestroy(Sender: TObject);
begin
fBmp.Free ;
end;
procedure TForm1.FormPaint(Sender: TObject);
begin
Canvas.Draw(0,0,fBmp); //將圖形繪製到Canvas
end;
//如果按下鼠標左鍵，用SetRect設置矩形fRect，使其只是一個點。
//用DrawFocusRect 把這個矩形畫出來
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if Button=mbLeft then begin
fDragging:=true;
SetRect(fRect,x,y,x,y);
Canvas.DrawFocusRect(fRect);
end;
end;
//鼠標移動時, 判斷是否在畫圖中（按下鼠標左鍵），DrawFocusRect重新設置矩形
//使右下角為當前鼠標位置，在調用DrawFocusRect畫出矩形
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if fDragging then begin
Canvas.DrawFocusRect(fRect);
fRect.Right := X ;
fRect.Bottom:= Y ;
Canvas.DrawFocusRect(fRect);
end;
end;
//判斷是否在畫圖中（按下鼠標左鍵），鼠標彈起時，
//DrawFocusRect重新設置矩形.關閉窗體
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if fDragging then begin
Canvas.DrawFocusRect(fRect);
fDragging:=false;
end;
ModalResult:=mrOK; //關閉窗體
end;
end.