再学 GDI+[35]: TGPPen - 虚线画笔位移 - SetDashOffset

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, ExtCtrls;



type

  TForm1 = class(TForm)

    Timer1: TTimer;

    procedure FormPaint(Sender: TObject);

    procedure Timer1Timer(Sender: TObject);

    procedure FormCreate(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GDIPOBJ, GDIPAPI;



var

  n: Integer;



procedure TForm1.FormCreate(Sender: TObject);

begin

  Timer1.Interval := 100;

end;



procedure TForm1.FormPaint(Sender: TObject);

var

  g: TGPGraphics;

  p: TGPPen;

begin

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

  p := TGPPen.Create(aclChocolate, 8);

  p.SetDashStyle(DashStyleDashDotDot);



  p.SetDashOffset(n);



  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, 0, 0);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, ClientWidth div 2, 0);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, ClientWidth, 0);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, ClientWidth, ClientHeight div 2);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, ClientWidth, ClientHeight);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, ClientWidth div 2, ClientHeight);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, 0, ClientHeight);

  g.DrawLine(p, ClientWidth div 2, ClientHeight div 2, 0, ClientHeight div 2);



  Dec(n);

  if n > Sqrt(Sqr(ClientWidth) + Sqr(ClientWidth)) then n := 0;



  p.Free;

  g.Free;

end;



procedure TForm1.Timer1Timer(Sender: TObject);

begin

  Repaint;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 167

  ClientWidth = 242

  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 Timer1: TTimer

    OnTimer = Timer1Timer

    Left = 112

    Top = 88

  end

end