再学 GDI+[61]: 路径画刷(1) - SetCenterColor、SetSurroundColors

本例效果图:

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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, 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 := '周边色    ';

  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.


 
   

窗体文件:

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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