再學GDI+[61] 路徑畫刷(1) - SetCenterColor、SetSurroundColor

本例效果圖:

代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, CheckLst, ExtCtrls, TeCanvas;
type
　TForm1 = class(TForm)
　　ButtonColor1: TButtonColor;
　　ButtonColor2: TButtonColor;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure ButtonColor1Click(Sender: TObject);
　　procedure ButtonColor2Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　ButtonColor1.Caption := '中心色　　';
　ButtonColor2.Caption := '周邊色　　';
　ButtonColor1.SymbolColor := clLime;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　rect: TGPRect;
　path: TGPGraphicsPath;
　pb: TGPPathGradientBrush;
　ColorArr: array[0..0] of TGPColor;
　num: Integer;
begin
　rect := MakeRect(20, 10, ClientWidth - 40, ClientHeight - 50);
　g := TGPGraphics.Create(Canvas.Handle);
　path := TGPGraphicsPath.Create;
　path.AddEllipse(rect);
　pb := TGPPathGradientBrush.Create(path);
　pb.SetCenterColor(ColorRefToARGB(ButtonColor1.SymbolColor));
　ColorArr[0] := ColorRefToARGB(ButtonColor2.SymbolColor);
　num := 1;
　pb.SetSurroundColors(PARGB(@ColorArr), num);
　g.FillEllipse(pb, rect);
　pb.Free;
　path.Free;
　g.Free;
end;
procedure TForm1.ButtonColor1Click(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.ButtonColor2Click(Sender: TObject);
begin
　Repaint;
end;
end.