再學 GDI+[70]: 路徑畫刷(10) - SetBlend

　本例效果圖:

　　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;
　　TrackBar3: TTrackBar;
　　TrackBar4: TTrackBar;
　　TrackBar5: TTrackBar;
　　TrackBar6: TTrackBar;
　　procedure FormPaint(Sender: TObject);
　　procedure FormCreate(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　　procedure TrackBar2Change(Sender: TObject);
　　procedure TrackBar3Change(Sender: TObject);
　　procedure TrackBar4Change(Sender: TObject);
　　procedure TrackBar5Change(Sender: TObject);
　　procedure TrackBar6Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　TrackBar1.Max := 10;
　TrackBar2.Max := 10;
　TrackBar3.Max := 10;
　TrackBar4.Max := 10;
　TrackBar5.Max := 10;
　TrackBar6.Max := 10;
　TrackBar1.Position := TrackBar1.Max;
　TrackBar2.Position := TrackBar2.Min;
　TrackBar3.Position := TrackBar3.Max;
　TrackBar4.Position := TrackBar4.Min;
　TrackBar5.Position := TrackBar5.Max div 2;
　TrackBar6.Position := TrackBar6.Max;
end;
procedure TForm1.FormPaint(Sender: TObject);
const
　pts: array[0..2] of TGPPoint = ((X:120; Y:10), (X:40; Y:140), (X:200;Y:140));
　colors: array[0..2] of TGPColor = (aclRed, aclGreen, aclYellow);
var
　g: TGPGraphics;
　path: TGPGraphicsPath;
　pb: TGPPathGradIEntBrush;
　blendFactors: array[0..2] of Single;
　pos: array[0..2] of Single;
　num: Integer;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　path := TGPGraphicsPath.Create;
　path.AddPolygon(PGPPoint(@pts), Length(pts));
　pb := TGPPathGradIEntBrush.Create(path);
　num := Length(colors);
　pb.SetSurroundColors(@colors, num); {SetBlend 只在設置包圍顏色時有效}
　blendFactors[0] := TrackBar1.Position / 10;
　blendFactors[1] := TrackBar2.Position / 10;
　blendFactors[2] := TrackBar3.Position / 10;
　pos[0] := TrackBar4.Position / 10;
　pos[1] := TrackBar5.Position / 10;
　pos[2] := TrackBar6.Position / 10;
　pb.SetBlend(@blendFactors, Psingle(@pos), Length(blendFactors));
　g.FillPath(pb, path);
　pb.Free;
　path.Free;
　g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar3Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar4Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar5Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar6Change(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 222
　ClIEntWidth = 242
　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 = 13
　　Top = 152
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
　object TrackBar2: TTrackBar
　　Left = 13
　　Top = 174
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 1
　　OnChange = TrackBar2Change
　end
　object TrackBar3: TTrackBar
　　Left = 13
　　Top = 196
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 2
　　OnChange = TrackBar3Change
　end
　object TrackBar4: TTrackBar
　　Left = 125
　　Top = 152
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 3
　　OnChange = TrackBar4Change
　end
　object TrackBar5: TTrackBar
　　Left = 125
　　Top = 174
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 4
　　OnChange = TrackBar5Change
　end
　object TrackBar6: TTrackBar
　　Left = 125
　　Top = 196
　　Width = 105
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 5
　　OnChange = TrackBar6Change
　end
end