再学 GDI+[68]: 路径画刷(8) - SetBlendTriangularShaped、SetBlendBellShape

本例效果图(颜色失真严重, 因为 GIF 最多只能接受 256 中颜色):

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代码文件:

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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:

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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