再学 GDI+[65]: 路径画刷(5) - SetGammaCorrection

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;



type

  TForm1 = class(TForm)

    procedure FormPaint(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GDIPOBJ, GDIPAPI;



procedure TForm1.FormPaint(Sender: TObject);

const

  ColorArr: array[0..2] of TGPColor = (aclRed, aclGreen, aclBlue);

var

  pts: array[0..2] of TGPPoint;

  g: TGPGraphics;

  path: TGPGraphicsPath;

  pb: TGPPathGradientBrush;

  num: Integer;

begin

  pts[0] := MakePoint(80, 10);

  pts[1] := MakePoint(10, 150);

  pts[2] := MakePoint(150, 150);



  g := TGPGraphics.Create(Canvas.Handle);



  path := TGPGraphicsPath.Create;

  path.AddPolygon(PGPPoint(@pts), Length(pts));

  //pb := TGPPathGradientBrush.Create(path); {这样建立中心默认白色; 按下一句中心默认黑色}

  pb := TGPPathGradientBrush.Create(PGPPoint(@pts), Length(pts)); {根据点数组建立路径画刷}

  pb.SetCenterColor(aclWhite);

  num := Length(pts);

  pb.SetSurroundColors(PARGB(@ColorArr), num);

  g.FillPath(pb, path);



  {使用灰度校正模式换个地方再画一次}

  pb.SetGammaCorrection(True);

  g.TranslateTransform(150, 0);

  g.FillPath(pb, path);



  pb.Free;

  path.Free;

  g.Free;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 163

  ClientWidth = 311

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

end