再学 GDI+[64]: 路径画刷(4) 还是 SetCenterColor、SetSurroundColors

在本例中没有指定 CenterColor, 将默认白色;
SurroundColors 原来是对应路径中的点(但按下面的做法在椭圆里不灵).

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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..3] of TGPColor = ($FFFF0000, $FF00FF00, $FF0000FF, $FFFFFF00);
var
  rt: TRect;
  pts: array of TGPPoint;
  g: TGPGraphics;
  path1, path2: TGPGraphicsPath;
  pb1,pb2: TGPPathGradientBrush;
  num: Integer;
begin
  rt := Bounds(10, 10, 150, 150);
  g := TGPGraphics.Create(Canvas.Handle);

  {矩形路径}
  path1 := TGPGraphicsPath.Create;
  path1.AddRectangle(MakeRect(rt));
  pb1 := TGPPathGradientBrush.Create(path1);
  num := 4;
  pb1.SetSurroundColors(PARGB(@ColorArr), num);
  g.FillPath(pb1, path1);

  {三角形路径}
  OffsetRect(rt, 160, 0);
  SetLength(pts, 3);
  pts[0] := MakePoint(rt.Left + (rt.Right-rt.Left) div 2, rt.Top);
  pts[1] := MakePoint(rt.Left, rt.Bottom);
  pts[2] := TGPPoint(rt.BottomRight);
  path2 := TGPGraphicsPath.Create;
  path2.AddPolygon(PGPPoint(pts), Length(pts));
  pb2 := TGPPathGradientBrush.Create(path2);
  num := 3;
  pb2.SetSurroundColors(PARGB(@ColorArr), num);
  g.FillPath(pb2, path2);

  pb1.Free;
  pb2.Free;
  path1.Free;
  path2.Free;
  g.Free;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 172
  ClientWidth = 327
  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