GdiPlus[19]: IGPPathGradientBrush 之 SetCenterPoint

测试效果图:

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测试代码:

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unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    procedure FormPaint(Sender: TObject);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GdiPlus, GdiPlusHelpers;

var
  Pt: TGPPointF;

procedure TForm1.FormPaint(Sender: TObject);
var
  Brush: IGPPathGradientBrush;
  Rect: TGPRect;
  Path: IGPGraphicsPath;
begin
  Rect.Initialize(10, 10, 200, 150);
  Path := TGPGraphicsPath.Create;
  Path.AddEllipse(Rect);

  Brush := TGPPathGradientBrush.Create(Path);
  Brush.CenterColor := $FF00FF00;
  Brush.SetSurroundColors([$FF000000]);

  Brush.SetCenterPoint(Pt);

  Canvas.ToGPGraphics.FillEllipse(Brush, Rect);
  Canvas.ToGPGraphics.DrawRectangle(TGPPen.Create($FFFF0000), Pt.X-3, Pt.Y-3, 6, 6);
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  Pt.X := X;
  Pt.Y := Y;
  Repaint;
end;

end.