MenuItem | .NET Windows Forms in a Nutshell

MenuItem

marshal by reference, disposable

System. Windows .Forms (system. windows .forms.dll)

class

This Menu class represents the submenus of either a MainMenu , ContextMenu , or other MenuItem object. You can add it to the MenuItems property of any of these classes to create such a submenu.

You can control the appearance of the item with a number of different properties. You can set the Text for the menu item, and it can be Enabled , and made Visible . The BarBreak and Break properties cause the menu item to start a new column in the menu, with and without a dividing line, respectively. Checked determines whether a check mark appears next to item text, and RadioCheck determines whether the check mark appears as a radio button instead of a checkmark. Note that you have to handle the mutual exclusion yourself. You can set a Shortcut key to associate with the item, and ShowShortcut determines whether the key is displayed to the right of the text. You can also find out which Mnemonic character is acting as an Alt key shortcut.

To support MDI applications, you can mark an item as the MdiListItem . The system will automatically create and maintain a child menu for this object with a list of the MDI windows owned by the parent Form .

Also for the benefit of MDI and similar applications, Menu objects allow the merging of their items to meld together menus from disparate sources. To control this, you can specify the MergeOrder of a particular item. This is essentially a numeric priority for the item when merging two submenus with the same name . A low number will appear higher in the menu than a higher number. It is best to think of these as numeric groups where the same numbers will be bundled together in the final menu.

In addition to the MergeOrder , you can specify the MergeType . This allows you to specify whether the system will Add() the item to the existing collection (this is the default), Remove() the item when merging (i.e., it will not appear in the final menu), Replace any existing items at the same position in the merged menu, or MergeItems : interleave the items with the existing items, adding and replacing as appropriate. Note that the settings on both parties in the merge affect the end results. It is best to play with these options until you get a feel for how menu merging works in practice.

To determine when items are being manipulated, you can bind to the Click , Popup (a child menu is about to appear), and Select (the item has been highlighted) events. You can programmatically raise these events with the PerformClick() and PerformSelect() methods .

Note that MenuItem objects also support OwnerDraw . See MeasureItemEventArgs and DrawItemEventArgs for more information on owner draw facilities.

 public class  MenuItem  : Menu {  // Public Constructors  public  MenuItem  ();    public  MenuItem  (MenuMerge  mergeType  , int  mergeOrder  , Shortcut  shortcut  , string  text  , EventHandler  onClick  ,          EventHandler  onPopup  , EventHandler  onSelect  , MenuItem[ ]  items  );    public  MenuItem  (string  text  );    public  MenuItem  (string  text  , EventHandler  onClick  );    public  MenuItem  (string  text  , EventHandler  onClick  , Shortcut  shortcut  );    public  MenuItem  (string  text  , MenuItem[ ]  items  );  // Public Instance Properties  public bool  BarBreak  {set; get; }    public bool  Break  {set; get; }    public bool  Checked  {set; get; }    public bool  DefaultItem  {set; get; }    public bool  Enabled  {set; get; }    public int  Index  {set; get; }    public override bool  IsParent  {get; }  // overrides Menu  public bool  MdiList  {set; get; }    public int  MergeOrder  {set; get; }    public MenuMerge  MergeType  {set; get; }    public char  Mnemonic  {get; }    public bool  OwnerDraw  {set; get; }    public Menu  Parent  {get; }    public bool  RadioCheck  {set; get; }    public Shortcut  Shortcut  {set; get; }    public bool  ShowShortcut  {set; get; }    public string  Text  {set; get; }    public bool  Visible  {set; get; }  // Protected Instance Properties  protected int  MenuID  {get; }  // Public Instance Methods  public virtual MenuItem  CloneMenu  ();    public virtual MenuItem  MergeMenu  ();    public void  MergeMenu  (MenuItem  itemSrc  );    public void  PerformClick  ();    public virtual void  PerformSelect  ();    public override string  ToString  ();  // overrides Menu   // Protected Instance Methods  protected void  CloneMenu  (MenuItem  itemSrc  );    protected override void  Dispose  (bool  disposing  );  // overrides Menu  protected virtual void  OnClick  (EventArgs  e  );    protected virtual void  OnDrawItem  (DrawItemEventArgs  e  );    protected virtual void  OnInitMenuPopup  (EventArgs  e  );    protected virtual void  OnMeasureItem  (MeasureItemEventArgs  e  );    protected virtual void  OnPopup  (EventArgs  e  );    protected virtual void  OnSelect  (EventArgs  e  );  // Events  public event EventHandler  Click  ;    public event DrawItemEventHandler  DrawItem  ;    public event MeasureItemEventHandler  MeasureItem  ;    public event EventHandler  Popup  ;    public event EventHandler  Select  ; }

Hierarchy

System.Object System.MarshalByRefObject System.ComponentModel.Component(System.ComponentModel.IComponen, System.IDisposable) Menu MenuItem

Returned By

Menu.{FindMenuItem() , MdiListItem} , MenuItemCollection.this

Passed To

ContextMenu.ContextMenu() , System.Windows.Forms.Design.IMenuEditorService.SetSelection() , MainMenu.MainMenu() , Menu.Menu() , MenuItemCollection.{Add() , AddRange() , Contains() , IndexOf() , Remove()} , MenuItem.MenuItem()