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再学GDI+[75]: 区域(4) - 根据区域剪切画板

时间:2012-05-23 | 栏目:Delphi教程 | 点击:

本例效果图:

代码文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls;
type
 TForm1 = class(TForm)
  CheckBox1: TCheckBox;
  procedure FormCreate(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);
  procedure CheckBox1Click(Sender: TObject);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
 rt: TRect;
 flag: Boolean;
 x1,y1: Integer;
procedure TForm1.FormCreate(Sender: TObject);
begin
 Self.Color := clWhite;
 rt := ClientRect;
 InflateRect(rt, -ClientWidth p 3, -ClientHeight p 3);
 CheckBox1.Caption := '剪切区域';
 CheckBox1.Checked := True;
 DoubleBuffered := True;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g : TGPGraphics;
 b: TGPSolidBrush;
 rgn: TGPRegion;
 str: string;
 font: TGPFont;
 RectF: TGPRectF;
 i: Integer;
begin
 RectF := MakeRect(0.0, 0, ClientWidth+10, ClientHeight);
 str := '';
 for i := 0 to 800 do str := str + IntToStr(Random(2));
 g := TGPGraphics.Create(Canvas.Handle);
 b := TGPSolidBrush.Create(aclBlue);
 rgn := TGPRegion.Create(MakeRect(rt));
 if CheckBox1.Checked then g.SetClip(rgn); {用区域剪切画板}
 font := TGPFont.Create(Canvas.Handle);
 g.DrawString(str, -1, font, RectF, nil, b);
 rgn.Free;
 font.Free;
 b.Free;
 g.Free;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 if PtInRect(rt, Point(X,Y)) then
 begin
  x1 := X;
  y1 := Y;
  flag := True;
 end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
begin
 if not flag then Exit;
 OffsetRect(rt, X-x1, Y-y1);
 x1 := X;
 y1 := Y;
 Repaint;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 flag := False;
end;
procedure TForm1.CheckBox1Click(Sender: TObject);
begin
 Repaint;
end;
end.

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