再學 GDI+[65]: 路徑畫刷(5) - SetGammaCorrection

本例效果圖:

　　代碼文件: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); {這樣建立中心默認白色; 按下一句中心默認黑色}
　pb := TGPPathGradIEntBrush.Create(PGPPoint(@pts), Length(pts)); {根據點數組建立路徑畫刷}
　pb.SetCenterColor(aclWhite);
　num := Length(pts);
　pb.SetSurroundColors(PARGB(@ColorArr), num);
　g.FillPath(pb, path);
　{使用灰度校正模式換個地方再畫一次}
　pb.SetGamMacorrection(True);
　g.TranslateTransform(150, 0);
　g.FillPath(pb, path);
　pb.Free;
　path.Free;
　g.Free;
end;
end.窗體文件: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