WinAPI: CloseFigure
本例效果图:



代码文件:
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    CheckBox1: TCheckBox;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure CheckBox1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  CheckBox1.Caption := '关闭路径';
end;

procedure TForm1.FormPaint(Sender: TObject);
begin
  SetBkMode(Canvas.Handle, TRANSPARENT);

  BeginPath(Canvas.Handle);
  Canvas.MoveTo(10, ClientHeight div 2);
  Canvas.LineTo(ClientWidth div 2, 10);
  Canvas.LineTo(ClientWidth - 10, ClientHeight div 2);
  if CheckBox1.Checked then CloseFigure(Canvas.Handle);
  EndPath(Canvas.Handle);

  Canvas.Pen.Color := clRed;
  StrokePath(Canvas.Handle);
end;

procedure TForm1.CheckBox1Click(Sender: TObject);
begin
  Repaint;
end;

end.
窗体文件:
object Form1: TForm1
  Left = 373
  Top = 260
  Caption = 'Form1'
  ClientHeight = 175
  ClientWidth = 234
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesigned
  OnCreate = FormCreate
  OnPaint = FormPaint
  PixelsPerInch = 96
  TextHeight = 13
  object CheckBox1: TCheckBox
    Left = 80
    Top = 136
    Width = 97
    Height = 17
    Caption = 'CheckBox1'
    TabOrder = 0
    OnClick = CheckBox1Click
  end
end