再學 GDI+[66]: 路徑畫刷(6) - SetInterpolationColors、GetRectangle

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);
var
　g : TGPGraphics;
　path: TGPGraphicsPath;
　pb: TGPPathGradIEntBrush;
　rt: TGPRect;
const
　pts: array[0..2] of TGPPoint = ((X:90; Y:10), (X:10; Y:160), (X:160; Y:160));
　colors: array[0..2] of TGPColor = (aclGreen, aclAqua, aclBlue);
　pos: array[0..2] of Single = (0.0, 0.25, 1.0); {顏色位置需要 >=0、<=1, 是百分比}
begin
　{三角}
　g := TGPGraphics.Create(Canvas.Handle);
　path := TGPGraphicsPath.Create;
　path.AddPolygon(PGPPoint(@pts), Length(pts));
　pb:= TGPPathGradIEntBrush.Create(path);
　pb.SetInterpolationColors(@colors, @pos, Length(colors)); {SetInterpolationColors}
　g.FillPath(pb, path);
　{矩形}
　pb.GetRectangle(rt); {GetRectangle}
　path.Reset;
　path.AddRectangle(rt);
　pb.Free;
　pb:= TGPPathGradIEntBrush.Create(path);
　pb.SetInterpolationColors(@colors, @pos, Length(colors));
　g.TranslateTransform(160, 0);
　g.FillPath(pb, path);
　{橢圓}
　path.Reset;
　path.AddEllipse(rt);
　pb.Free;
　pb:= TGPPathGradIEntBrush.Create(path);
　pb.SetInterpolationColors(@colors, @pos, Length(colors));
　g.TranslateTransform(160, 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 = 164
　ClIEntWidth = 491
　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