再学 GDI+[48]: 路径 StartFigure、CloseFigure、CloseAllFigures

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;

procedure TForm1.FormCreate(Sender: TObject);
begin
  CheckBox1.Caption := 'CloseFigure';
  CheckBox2.Caption := 'CloseAllFigures';
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g: TGPGraphics;
  path: TGPGraphicsPath;
  p: TGPPen;
  b: TGPBrush;
  pts1,pts2,pts3: array[0..2] of TGPPoint;
  i: Integer;
begin
  pts1[0] := MakePoint(0, 30);
  pts1[1] := MakePoint(30, 0);
  pts1[2] := MakePoint(60, 30);

  for i := 0 to Length(pts1) do
  begin
    pts2[i].X := pts1[i].X + 80;
    pts2[i].Y := pts1[i].Y + 20;
    pts3[i].X := pts2[i].X + 80;
    pts3[i].Y := pts2[i].Y + 20;
  end;

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

  path := TGPGraphicsPath.Create;
  path.StartFigure;
  path.AddLines(PGPPoint(@pts1), Length(pts1));
  path.StartFigure;
  path.AddLines(PGPPoint(@pts2), Length(pts2));
  path.StartFigure;
  path.AddLines(PGPPoint(@pts3), Length(pts3));

  if CheckBox1.Checked then path.CloseFigure;
  if CheckBox2.Checked then path.CloseAllFigures;

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

  g.DrawPath(p, path);

  b.Free;
  p.Free;
  path.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 = 139
  ClientWidth = 227
  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 = 28
    Top = 105
    Width = 97
    Height = 17
    Caption = 'CheckBox1'
    TabOrder = 0
    OnClick = CheckBox1Click
  end
  object CheckBox2: TCheckBox
    Left = 120
    Top = 105
    Width = 97
    Height = 17
    Caption = 'CheckBox2'
    TabOrder = 1
    OnClick = CheckBox2Click
  end
end