再學 GDI+[68]: 路徑畫刷(8) - SetBlendTriangularShaped、SetBlendBellShape

本例效果圖(顏色失真嚴重, 因為 GIF 最多只能接受 256 中顏色):

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, ComCtrls, StdCtrls, ExtCtrls;
type
　TForm1 = class(TForm)
　　TrackBar1: TTrackBar;
　　TrackBar2: TTrackBar;
　　RadioGroup1: TRadioGroup;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure RadioGroup1Click(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　　procedure TrackBar2Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　TrackBar1.Max := 100;
　TrackBar2.Max := 100;
　TrackBar1.Position := TrackBar1.Max;
　TrackBar2.Position := TrackBar2.Max;
　TrackBar1.ShowSelRange := False;
　TrackBar2.ShowSelRange := False;
　TrackBar1.Height := 23;
　TrackBar2.Height := 23;
　RadioGroup1.Items.CommaText := 'BlendTriangularShape, SetBlendBellShape';
　RadioGroup1.ItemIndex := 0;
　DoubleBuffered := True;
end;
procedure TForm1.FormPaint(Sender: TObject);
const
　colors: array[0..0] of TGPColor = (aclRed);
var
　g: TGPGraphics;
　path: TGPGraphicsPath;
　pb: TGPPathGradIEntBrush;
　num: Integer;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　path := TGPGraphicsPath.Create;
　path.AddRectangle(MakeRect(30,10,160,150));
　pb:= TGPPathGradIEntBrush.Create(path);
　num := Length(colors);
　pb.SetSurroundColors(@colors, num);
　pb.SetCenterColor(aclYellow);
　{SetBlendTriangularShape 與 SetBlendBellShape 參數2的默認值都是 1.0}
　case RadioGroup1.ItemIndex of
　　0: pb.SetBlendTriangularShape(TrackBar1.Position/100, TrackBar2.Position/100);
　　1: pb.SetBlendBellShape(TrackBar1.Position/100, TrackBar2.Position/100);
　end;
　g.FillPath(pb, path);
　pb.Free;
　path.Free;
　g.Free;
end;
procedure TForm1.RadioGroup1Click(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 261
　ClIEntWidth = 221
　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 TrackBar1: TTrackBar
　　Left = 0
　　Top = 167
　　Width = 113
　　Height = 45
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
　object TrackBar2: TTrackBar
　　Left = 108
　　Top = 167
　　Width = 113
　　Height = 45
　　TabOrder = 1
　　OnChange = TrackBar2Change
　end
　object RadioGroup1: TRadioGroup
　　Left = 8
　　Top = 192
　　Width = 206
　　Height = 61
　　Caption = 'RadioGroup1'
　　TabOrder = 2
　　OnClick = RadioGroup1Click
　end
end