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

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.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 258
　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
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object ButtonColor1: TButtonColor
　　Left = 24
　　Top = 225
　　Caption = 'ButtonColor1'
　　TabOrder = 0
　　OnClick = ButtonColor1Click
　end
　object ButtonColor2: TButtonColor
　　Left = 112
　　Top = 225
　　Caption = 'ButtonColor2'
　　TabOrder = 1
　　OnClick = ButtonColor2Click
　end
end