Flex - Tree Control


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Introduction

The Tree control displays hierarchical data arranged as an expandable tree.

Class Declaration

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

public class Tree 
   extends List
      implements IIMESupport

Public Properties

S.No Property & Description
1

dataDescriptor : mx.controls.treeClasses:ITreeDataDescriptor

Returns the current ITreeDataDescriptor.

2

dataProvider : Object

[override] An object that contains the data to be displayed.

3

dragMoveEnabled : Boolean

[override] Indicates that items can be moved instead of just copied from the Tree control as part of a drag-and-drop operation.

4

firstVisibleItem : Object

The item that is currently displayed in the top row of the tree.

5

hasRoot : Boolean

[read-only] Indicates that the current dataProvider has a root item; for example, a single top node in a hierarchical structure.

6

itemIcons : Object

An object that specifies the icons for the items.

7

maxHorizontalScrollPosition : Number

[override] The maximum value for the maxHorizontalScrollPosition property for the Tree control.

8

openItems : Object

The items that have been opened or set opened.

9

showRoot : Boolean

Sets the visibility of the root item.

Public Methods

S.No Method & Description
1

Tree()

Constructor.

2

expandChildrenOf(item:Object, open:Boolean):void

Opens or closes all the tree items below the specified item.

3

expandItem(item:Object, open:Boolean, animate:Boolean = false, dispatchEvent:Boolean = false, cause:Event = null):void

Opens or closes a branch item.

4

getParentItem(item:Object):*

Returns the known parent of a child item.

5

isItemOpen(item:Object):Boolean

Returns true if the specified item branch is open (is showing its children).

6

setItemIcon(item:Object, iconID:Class, iconID2:Class):void

Sets the associated icon for the item.

Protected Methods

S.No Method & Description
1

dragCompleteHandler(event:DragEvent):void

[override] Handles DragEvent.DRAG_COMPLETE events.

2

dragDropHandler(event:DragEvent):void

[override] Handles DragEvent.DRAG_DROP events.

3

initListData(item:Object, treeListData:mx.controls.treeClasses:TreeListData):void

Initializes a TreeListData object that is used by the tree item renderer.

4

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

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

Events

S.No Event & Description
1

itemClose

Dispatched when a branch is closed or collapsed.

2

itemOpen

Dispatched when a branch is opened or expanded.

3

itemOpening

Dispatched when a branch open or close is initiated.

Methods Inherited

This class inherits methods from the following classes −

  • mx.controls.List
  • mx.controls.listClasess.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 Tree Control Example

Let us follow the following steps to check usage of Tree 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[
         [Bindable]
         public var selectedNode:XML;

         // Event handler for the Tree control change event.
         public function treeChanged(event:Event):void {
            selectedNode = Tree(event.target).selectedItem as XML;
         }
      ]]>
   </fx:Script>
   
   <fx:Declarations>
      <fx:XMLList id = "treeData">
         <node label = "E-Mail Box">
            <node label = "Inbox">
            <node label = "Client" />
               <node label = "Product" />
               <node label = "Personal" />
            </node>
            
            <node label = "Sent Items">
               <node label = "Professional" />
               <node label = "Personal" />
            </node>
            
            <node label = "Deleted Items" />
            <node label = "Spam" />
         </node>    
      </fx:XMLList>
   </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 = "treePanel" title = "Using Tree" 
            width = "500" height = "300">
            <s:layout>
               <s:VerticalLayout  gap = "10" verticalAlign = "middle" 
                  horizontalAlign = "center" />	
            </s:layout>
               
            <mx:Tree id = "tree" width = "95%" height = "75%" 
               labelField = "@label" showRoot = "false" 
               dataProvider = "{treeData}" change = "treeChanged(event)" />
            <s:TextArea height = "20%" width = "95%" 
               text = "Selected Item: {selectedNode.@label}" />
         </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 Tree Control
flex_complex_controls.htm

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