再学 GDI+[62]: 路径画刷(2) - SetCenterPoint、GetCenterPoint

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, CheckLst, ExtCtrls, TeCanvas;

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

var
Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI;

var
rect: TGPRect;
pt: TGPPoint;
pb: TGPPathGradientBrush;

procedure TForm1.FormCreate(Sender: TObject);
var
path: TGPGraphicsPath;
ColorSurround: TGPColor;  {只用一种包围色, 就别用数组了}
num: Integer;
begin
rect := MakeRect(10, 10, ClientWidth-20, ClientHeight-20);
path := TGPGraphicsPath.Create;
path.AddEllipse(rect);

pb := TGPPathGradientBrush.Create(path);
pb.SetCenterColor(aclLime);

pb.GetCenterPoint(pt);

ColorSurround := aclBlack;
num := 1;
pb.SetSurroundColors(@ColorSurround, num);

path.Free;

DoubleBuffered := True;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
pb.Free;
end;

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

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

procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(aclRed);

g.FillEllipse(pb, rect);
pb.SetCenterPoint(pt);
g.DrawRectangle(p, pt.X-3, pt.Y-3, 6, 6);

p.Free;
g.Free;
end;

end.

object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 164
ClientWidth = 208
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
Position = poDesktopCenter
OnCreate = FormCreate
OnDestroy = FormDestroy
OnMouseDown = FormMouseDown
OnMouseUp = FormMouseUp
OnPaint = FormPaint
PixelsPerInch = 96
TextHeight = 13
end