本例效果图(颜色失真严重, 因为 GIF 最多只能接受 256 中颜色):
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86285.gif)
代码文件:
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86285.gif)
代码文件:
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 与 SetBlendBellShape 参数2的默认值都是 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.窗体文件:
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