跑马灯的实现

昨天去火车站买票，看到火车站上的跑马灯文字提示很好玩，就自己编个小程序娱乐了一下~~

很简单的代码。。。

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    lbl1: TLabel;
    lbl2: TLabel;
    tmr1: TTimer;
    procedure FormCreate(Sender: TObject);
    procedure tmr1Timer(Sender: TObject);
    procedure FormDblClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  lbl1.Left := 330;
  lbl2.Left := 330;
  lbl1.Top  := 160;
  lbl2.Top  := 160;

end;

procedure TForm1.FormDblClick(Sender: TObject);
begin
  lbl1.Caption := InputBox('输入:','请输入跑马灯的文字:','我是跑马灯,呵呵呵呵');
  lbl2.Caption := lbl1.Caption;
end;

procedure TForm1.tmr1Timer(Sender: TObject);
begin

  if lbl1.Left <= 0 then         //如果到了边界，label2显示，并开始移动
    begin
      lbl2.Visible := true;
      lbl2.Left := lbl2.Left - 1;
    end
  else
    begin
      lbl2.Visible := false;        //如果还没到边界，label2不显示，初始化label的边界
      lbl2.Left := Form1.Width;
    end;

  if (lbl1.Left + lbl1.Width) < 0 then   //如果移动到了不显示的位置，从label2的当前位置继续移动
    lbl1.Left := lbl2.Left;

  lbl1.Left := lbl1.Left - 1;
end;

end.