学习 Message(22): WM_SYSCOMMAND 消息[六] : 系统菜单综合操作示例

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)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  protected
    procedure WMSysCommand(var Message: TWMSysCommand); message WM_SYSCOMMAND;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{定义两个菜单命令 ID 常数, 自定义的此类常数应该小于 $F000, 因为系统使用的都大于这个数}
const
  MenuCmdID1 = 101;
  MenuCmdID2 = 102;

{添加}
procedure TForm1.Button1Click(Sender: TObject);
var
  h: HMENU;
begin
  {系统菜单句柄}
  h := GetSystemMenu(Handle, False);
  AppendMenu(h, MFT_STRING, MenuCmdID1, '新添加的菜单项');
end;

{插入}
procedure TForm1.Button2Click(Sender: TObject);
var
  h: HMENU;
begin
  h := GetSystemMenu(Handle, False);
  {这是插入在 "还原" 菜单(SC_RESTORE) 前面}
  InsertMenu(h, SC_RESTORE, MFT_STRING, MenuCmdID2, '插入的菜单项');
end;

{修改}
procedure TForm1.Button3Click(Sender: TObject);
var
  h: HMENU;
begin
  h := GetSystemMenu(Handle, False);
  ModifyMenu(h, SC_MOVE, MF_BYCOMMAND, SC_MOVE, '这是我改的');
end;

{删除}
procedure TForm1.Button4Click(Sender: TObject);
var
  h: HMENU;
begin
  h := GetSystemMenu(Handle, False);
  {这是删除的 "关闭" 菜单, 此时窗口的关闭按钮会变灰}
  DeleteMenu(h, SC_CLOSE, MF_BYCOMMAND);
end;

{恢复}
procedure TForm1.Button5Click(Sender: TObject);
begin
  GetSystemMenu(Handle, True);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption := '添加';
  Button2.Caption := '插入';
  Button3.Caption := '修改';
  Button4.Caption := '删除';
  Button5.Caption := '恢复';
end;

procedure TForm1.WMSysCommand(var Message: TWMSysCommand);
var
  h: HMENU;
  buf: array[Byte] of Char;
begin
  h := GetSystemMenu(Handle, False);
  case Message.CmdType of
    MenuCmdID1: begin
      GetMenuString(h, MenuCmdID1, buf, Length(buf), MF_BYCOMMAND);
      ShowMessage(buf);
    end;
    MenuCmdID2: begin
      GetMenuString(h, MenuCmdID2, buf, Length(buf), MF_BYCOMMAND);
      ShowMessage(buf);
    end;
  end;
  inherited;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 191
  ClientWidth = 206
  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 Button1: TButton
    Left = 48
    Top = 20
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 48
    Top = 51
    Width = 75
    Height = 25
    Caption = 'Button2'
    TabOrder = 1
    OnClick = Button2Click
  end
  object Button3: TButton
    Left = 48
    Top = 82
    Width = 75
    Height = 25
    Caption = 'Button3'
    TabOrder = 2
    OnClick = Button3Click
  end
  object Button4: TButton
    Left = 48
    Top = 113
    Width = 75
    Height = 25
    Caption = 'Button4'
    TabOrder = 3
    OnClick = Button4Click
  end
  object Button5: TButton
    Left = 48
    Top = 144
    Width = 75
    Height = 25
    Caption = 'Button5'
    TabOrder = 4
    OnClick = Button5Click
  end
end