Flex - Menu Control

Introduction

The Menu control creates a pop-up menu of singly selectable choices or menuitems. The popped up menu can have as many levels of submenus as needed.

Class Declaration

Following is the declaration for mx.controls.Menu class −

public class Menu 
   extends List 
      implements IFocusManagerContainer

Public Properties

Sr.No	Property & Description
1	dataDescriptor : IMenuDataDescriptor The object that accesses and manipulates data in the data provider.
2	hasRoot : Boolean [read-only] A flag that indicates that the current data provider has a root node; for example, a single top node in a hierarchical structure.
3	parentMenu : Menu The parent menu in a hierarchical chain of menus, where the current menu is a submenu of the parent.
4	showRoot : Boolean A Boolean flag that specifies whether to display the data provider's root node.

Public Methods

Sr.No	Method & Description
1	Menu() Constructor.
2	createMenu(parent:DisplayObjectContainer, mdp:Object, showRoot:Boolean = true):Menu [static] Creates and returns an instance of the Menu class.
3	hide():void Hides the Menu control and any of its submenus if the Menu control is visible.
4	popUpMenu(menu:Menu, parent:DisplayObjectContainer, mdp:Object):void [static] Sets the dataProvider of an existing Menu control and places the Menu control in the specified parent container.
5	show(xShow:Object = null, yShow:Object = null):void Shows the Menu control.

Protected Methods

Sr.No	Method & Description
1	makeListData(data:Object, uid:String, rowNum:int):BaseListData [override] Creates a new MenuListData instance and populates the fields based on the input data provider item.
2	measure():void [override] Calculates the preferred width and height of the Menu based on the widths and heights of its menu items.
3	setMenuItemToggled(item:Object, toggle:Boolean):void Toggles the menu item.

Sr.No

Method & Description

makeListData(data:Object, uid:String, rowNum:int):BaseListData

[override] Creates a new MenuListData instance and populates the fields based on the input data provider item.

measure():void

[override] Calculates the preferred width and height of the Menu based on the widths and heights of its menu items.

setMenuItemToggled(item:Object, toggle:Boolean):void

Toggles the menu item.

Events

Sr.No	Event & Description
1	change Dispatched when selection changes as a result of user interaction.
2	itemClick Dispatched when a menu item is selected.
3	itemRollOut Dispatched when a user rolls the mouse out of a menu item.
4	itemRollOver Dispatched when a user rolls the mouse over a menu item.
5	menuHide Dispatched when a menu or submenu is dismissed.
6	menuShow Dispatched when a menu or submenu opens.

Methods Inherited

This class inherits methods from the following classes −

mx.controls.List
mx.controls.listClasses.ListBase
mx.core.ScrollControlBase
mx.core.UIComponent
mx.core.FlexSprite
flash.display.Sprite
flash.display.DisplayObjectContainer
flash.display.InteractiveObject
flash.display.DisplayObject
flash.events.EventDispatcher
Object

Flex Menu Control Example

Let us follow the following steps to check usage of Menu control in a Flex application by creating a test application −

Step	Description
1	Create a project with a name HelloWorld under a package com.tutorialspoint.client as explained in the Flex - Create Application chapter.
2	Modify HelloWorld.mxml as explained below. Keep rest of the files unchanged.
3	Compile and run the application to make sure business logic is working as per the requirements.

Following is the content of the modified mxml file src/com.tutorialspoint/HelloWorld.mxml.

<?xml version = "1.0" encoding = "utf-8"?>
<s:Application xmlns:fx = "http://ns.adobe.com/mxml/2009"
   xmlns:s = "library://ns.adobe.com/flex/spark"
   xmlns:mx = "library://ns.adobe.com/flex/mx"
   width = "100%" height = "100%" minWidth = "500" minHeight = "500">
   
   <fx:Style source = "/com/tutorialspoint/client/Style.css" />	
   <fx:Script>
      <![CDATA[
         import mx.controls.Menu;
         import mx.events.MenuEvent;
         
         protected var menu:Menu; 
         protected function showMenu(event:MouseEvent):void {
            menu = Menu.createMenu(null, menuData, false);
            menu.labelField = "@label";
            menu.show(mainContainer.x+menuPanel.x+ 2,
            mainContainer.y +menuPanel.y+32);
            menu.addEventListener(MenuEvent.CHANGE,onMenuChange);
         }

         protected function hideMenu(event:MouseEvent):void {
            menu.hide();
         }
         
         protected function onMenuChange(event:MenuEvent):void {
            lblSelected.text =  event.label;
         }
      ]]>
   </fx:Script>
   
   <fx:Declarations>
      <fx:XML format = "e4x" id = "menuData">
         <root>
            <menuitem label = "Menu Item A" >
               <menuitem label = "SubMenu Item A 1" enabled = "false" />
               <menuitem label = "SubMenu Item A 2" />
            </menuitem>
            
            <menuitem label = "Menu Item B" type = "check" toggled = "true" />
            <menuitem label = "Menu Item C" type = "check" toggled = "false" />
            <menuitem type = "separator" />
            
            <menuitem label = "Menu Item D" >
               <menuitem label = "SubMenu Item D 1" type = "radio" 
                  groupName = "one" />
               <menuitem label = "SubMenu Item D 2" type = "radio" 
                  groupName = "one" toggled = "true" />
               <menuitem label = "SubMenu Item D 3" type = "radio" 
                  groupName = "one" />
            </menuitem>
         </root>
      </fx:XML>
   </fx:Declarations>
   
   <s:BorderContainer width = "630" height = "480" id = "mainContainer" 
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "50" 
         horizontalAlign = "center" verticalAlign = "middle">
         <s:Label id = "lblHeader" text = "Complex Controls Demonstration" 
            fontSize = "40" color = "0x777777" styleName = "heading" />
         
         <s:Panel id = "menuPanel" title = "Using Menu" width = "500" 
            height = "300">
            <s:layout>
               <s:VerticalLayout  gap = "10" verticalAlign = "middle" 
                  horizontalAlign = "center" />	
            </s:layout>		
            
            <s:HGroup>
               <s:Button label = "Show Menu" click = "showMenu(event)" />
               <s:Button label = "Hide Menu" click = "hideMenu(event)" />
            </s:HGroup>
            
            <s:HGroup>
               <s:Label text = "Menu Item selected:" />
               <s:Label id = "lblSelected" fontWeight = "bold" />	
            </s:HGroup>
         </s:Panel>
      </s:VGroup>	 
   </s:BorderContainer>	
</s:Application>

Once you are ready with all the changes done, let us compile and run the application in normal mode as we did in Flex - Create Application chapter. If everything is fine with your application, it will produce the following result: [ Try it online ]

flex_complex_controls.htm