再学 GDI+[52]: 路径 - Reverse、Reset

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, StdCtrls;



type

  TForm1 = class(TForm)

    CheckBox1: TCheckBox;

    CheckBox2: TCheckBox;

    procedure FormCreate(Sender: TObject);

    procedure FormPaint(Sender: TObject);

    procedure CheckBox1Click(Sender: TObject);

    procedure CheckBox2Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GDIPOBJ, GDIPAPI;



var pts: array[0..6] of TGPPoint;



procedure TForm1.FormCreate(Sender: TObject);

begin

  pts[0].X := 10;  pts[0].Y := 50;

  pts[1].X := 40;  pts[1].Y := 90;

  pts[2].X := 80;  pts[2].Y := 10;

  pts[3].X := 110;  pts[3].Y := 50;

  pts[4].X := 140;  pts[4].Y := 10;

  pts[5].X := 180; pts[5].Y := 90;

  pts[6].X := 210; pts[6].Y := 50;



  CheckBox1.Caption := '翻转路径中的点';

  CheckBox2.Caption := '清空路径中的点';

end;



procedure TForm1.FormPaint(Sender: TObject);

var

  g: TGPGraphics;

  p: TGPPen;

  path: TGPGraphicsPath;

  PathPts: array of TGPPoint;

  i: Integer;

begin

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

  p := TGPPen.Create(aclRed, 2);

  path := TGPGraphicsPath.Create;

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



  if CheckBox1.Checked then path.Reverse;

  if CheckBox2.Checked then path.Reset;

  {Reset 时, 会清空 PathPoints 和 PathTypes 数组并将 FillMode 设置为 FillModeAlternate}



  SetLength(PathPts, path.GetPointCount);

  path.GetPathPoints(PGPPoint(PathPts), Length(PathPts));



  Canvas.Pen.Color := clGray;

  for i := Low(PathPts) to High(PathPts) do

    Canvas.TextOut(PathPts[i].X, PathPts[i].Y, IntToStr(i+1));



  g.DrawPath(p, path);



  path.Free;

  p.Free;

  g.Free;

end;



procedure TForm1.CheckBox1Click(Sender: TObject);

begin

  Repaint;

end;



procedure TForm1.CheckBox2Click(Sender: TObject);

begin

  Repaint;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 156

  ClientWidth = 232

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object CheckBox1: TCheckBox

    Left = 12

    Top = 126

    Width = 113

    Height = 17

    Caption = 'CheckBox1'

    TabOrder = 0

    OnClick = CheckBox1Click

  end

  object CheckBox2: TCheckBox

    Left = 123

    Top = 126

    Width = 106

    Height = 17

    Caption = 'CheckBox2'

    TabOrder = 1

    OnClick = CheckBox2Click

  end

end