unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    TrayIcon1: TTrayIcon;
    Button1: TButton;
    procedure TrayIcon1Click(Sender: TObject);
    procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{关闭}
procedure TForm1.Button1Click(Sender: TObject);
begin
  Application.Terminate;
end;

{点击关闭按钮时让窗体最小化到系统托盘}
procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  Tag := Ord(WindowState);
  WindowState := wsMinimized;
  TrayIcon1.SetDefaultIcon;
  TrayIcon1.Visible := True;
  Hide;
  CanClose := False;
end;

{点击系统托盘中的图标恢复窗口}
procedure TForm1.TrayIcon1Click(Sender: TObject);
begin
  TrayIcon1.Visible := False;
  Show;
  WindowState := TWindowState(tag);
  SetForegroundWindow(Handle);
end;

end.

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 339
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCloseQuery = FormCloseQuery
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 232
    Top = 40
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object TrayIcon1: TTrayIcon
    OnClick = TrayIcon1Click
    Left = 160
    Top = 104
  end
end

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

  IMyInterface1 = interface
    function Func(a,b: Integer): Integer;
  end;

  TAdd = class(TInterfacedObject, IMyInterface1)
  public
    function Func(a: Integer; b: Integer): Integer;
    destructor Destroy; override;
  end;

  TMul = class(TInterfacedObject, IMyInterface1)
  public
    function Func(a: Integer; b: Integer): Integer;
    destructor Destroy; override;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TAdd }

destructor TAdd.Destroy;
begin
  ShowMessage('TAdd.Destroy');
  inherited;
end;

function TAdd.Func(a, b: Integer): Integer;
begin
  Result := a + b;
end;

{ TMul }

destructor TMul.Destroy;
begin
  ShowMessage('TMul.Destroy');
  inherited;
end;

function TMul.Func(a, b: Integer): Integer;
begin
  Result := a * b;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  I: IMyInterface1;
begin
  I := TAdd.Create;
  ShowMessage(IntToStr(I.Func(9, 9))); {18}

  I := TMul.Create;  {I 在指向新的目标前会先释放前面所属的类}
  ShowMessage(IntToStr(I.Func(9, 9))); {81}
end;

end.

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    TrayIcon1: TTrayIcon;
    PopupMenu1: TPopupMenu;
    aaa1: TMenuItem;
    bbb1: TMenuItem;
    ccc1: TMenuItem;
    procedure FormCreate(Sender: TObject);
    procedure TrayIcon1DblClick(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  {指定图标, 这里是用程序相同的图标; 也可在设计时选择, 还可以指定一个图标组, 再用 IconIndex 切换}
  TrayIcon1.Icon := Application.Icon;
  {指定右键菜单}
  TrayIcon1.PopupMenu := PopupMenu1;
  {使之可见}
  TrayIcon1.Visible := True;
end;

{给图标添加到双击事件}
procedure TForm1.TrayIcon1DblClick(Sender: TObject);
begin
  ShowMessage('OnDblClick');
end;

end.

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 339
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object TrayIcon1: TTrayIcon
    OnDblClick = TrayIcon1DblClick
    Left = 152
    Top = 88
  end
  object PopupMenu1: TPopupMenu
    Left = 216
    Top = 88
    object aaa1: TMenuItem
      Caption = 'aaa'
    end
    object bbb1: TMenuItem
      Caption = 'bbb'
    end
    object ccc1: TMenuItem
      Caption = 'ccc'
    end
  end
end