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


    本例效果图:



    代码文件:
    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:
    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
    
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  • 原文地址:https://www.cnblogs.com/del/p/1231730.html
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