unit1.pas

本光盘是《Delphi 7应用教程》一书的配套光盘

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Button1: TButton;
    Timer1: TTimer;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject); 
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  Label1.Left:=Form1.Width ;  //标签控件设置在右边界之外
  Timer1.Enabled:=True; //启动时钟控件，以自动移动文本
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
    if (Label1.Left+Label1.Width>0) then//如果没有移出窗体
      Label1.Left:=Label1.Left-20//Left属性值减20
    else
      Label1.Left:=Form1.Width;//移出左边界时从窗体右边界移入
end;

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (Key=vk_Left)And(ssAlt in Shift)And(Timer1.Enabled=False) then
    //表示按下左光标键和Alt键，同时时钟组件不可用
    if Label1.Left+Label1.Width>0 then
      Label1.Left:=Label1.Left-2
    else
      Label1.Left:=Form1.Width; 
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
 Label1.Left:=Form1.Width ;  //标签控件设置在右边界之外
  Timer1.Enabled:=False;
end;

end.