再学GDI+[63]: 路径画刷(3)

本例效果图:

代码文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, CheckLst, ExtCtrls, TeCanvas, ComCtrls;
type
　TForm1 = class(TForm)
　　TrackBar1: TTrackBar;
　　TrackBar2: TTrackBar;
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　　procedure TrackBar2Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
　rect: TGPRect;
　pb: TGPPathGradientBrush;
procedure TForm1.FormCreate(Sender: TObject);
var
　path: TGPGraphicsPath;
　ColorSurround: TGPColor;
　num: Integer;
begin
　rect := MakeRect(10, 10, ClientWidth-40, ClientHeight-40);
　path := TGPGraphicsPath.Create;
　path.AddEllipse(rect);
　pb := TGPPathGradientBrush.Create(path);
　pb.SetCenterColor(aclLime);
　ColorSurround := aclBlack;
　num := 1;
　pb.SetSurroundColors(@ColorSurround, num);
　path.Free;
　DoubleBuffered := True;
　TrackBar1.Max := 100;
　TrackBar2.Max := 100;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　pb.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　x,y: Single;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclRed);
　g.FillEllipse(pb, rect);
　pb.SetCenterPoint(MakePoint(rect.X + rect.Width div 2, rect.Y + rect.Height div 2));
　{SetFocusScales}
　pb.SetFocusScales(TrackBar1.Position / 100, TrackBar2.Position / 100);
　{GetFocusScales}
　pb.GetFocusScales(x, y);
　Text := Format('%f,%f',[x,y]);
　p.Free;
　g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
　Repaint;
end;
end.