// Copyright 2007. Adobe Systems Incorporated. All Rights Reserved.
  package fl.accessibility {
  
          import flash.accessibility.Accessibility;
          import flash.events.Event;
          import fl.controls.ComboBox;
          import fl.core.UIComponent;
          
          

The @ax-student-ar-fl-accessibility-ComboBoxAccImpl class, also called the ComboBox Accessibility Implementation class, is used to make a ComboBox component accessible. <p>The @ax-student-ar-fl-accessibility-ComboBoxAccImpl class supports system roles, object-based events, and states.</p> <p>A ComboBox reports the role <code>ROLE_SYSTEM_COMBOBOX</code> (0x2E) to a screen reader. Items of a ComboBox report the role <code>ROLE_SYSTEM_LISTITEM</code> (0x22).</p> <p>A ComboBox reports the following states to a screen reader:</p> <ul> <li><code>STATE_SYSTEM_NORMAL</code> (0x00000000)</li> <li><code>STATE_SYSTEM_UNAVAILABLE</code> (0x00000001)</li> <li><code>STATE_SYSTEM_FOCUSED</code> (0x00000004)</li> <li><code>STATE_SYSTEM_PRESSED</code> (0x00000008)</li> <li><code>STATE_SYSTEM_CHECKED</code> (0x00000010)</li> <li><code>STATE_SYSTEM_FOCUSABLE</code> (0x00100000)</li> </ul> <p>Additionally, items of a ComboBox report the following states:</p> <ul> <li><code>STATE_SYSTEM_SELECTED</code> (0x00000002)</li> <li><code>STATE_SYSTEM_SELECTABLE</code> (0x00200000)</li> </ul> <p>A ComboBox dispatches the following events to a screen reader:</p> <ul> <li><code>EVENT_OBJECT_SELECTION</code> (0x8006)</li> <li><code>EVENT_OBJECT_STATECHANGE</code> (0x800A)</li> <li><code>EVENT_OBJECT_NAMECHANGE</code> (0x800C)</li> <li><code>EVENT_OBJECT_VALUECHANGE</code> (0x800E)</li> </ul>
see: fl.controls.ComboBox ComboBox @langversion 3.0 @playerversion Flash 9.0.28.0

  
          public class @ax-student-ar-fl-accessibility-ComboBoxAccImpl extends AccImpl {
                  //--------------------------------------------------------------------------
                  //  Class initialization
                  //--------------------------------------------------------------------------
          
          

@private Static variable triggering the <code>hookAccessibility()</code> method. This is used for initializing @ax-student-ar-fl-accessibility-ComboBoxAccImpl class to hook its <code>createAccessibilityImplementation()</code> method to ComboBox class before it gets called from UIComponent. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static var accessibilityHooked:Boolean = hookAccessibility();
  
          

@private Static method for swapping the <code>createAccessibilityImplementation()</code> method of ComboBox with the @ax-student-ar-fl-accessibility-ComboBoxAccImpl class. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static function hookAccessibility():Boolean {
                          ComboBox.createAccessibilityImplementation = createAccessibilityImplementation;
                          return true;
                  }
          
                  //--------------------------------------------------------------------------
                  //  Class constants
                  //--------------------------------------------------------------------------
          
          

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const ROLE_SYSTEM_LISTITEM:uint = 0x22;
                  
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const STATE_SYSTEM_FOCUSED:uint = 0x00000004;
                  
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const STATE_SYSTEM_SELECTABLE:uint = 0x00200000;
          
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const STATE_SYSTEM_SELECTED:uint = 0x00000002;
                  
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const EVENT_OBJECT_VALUECHANGE:uint = 0x800E;
                  
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const EVENT_OBJECT_SELECTION:uint = 0x8006;
          
                  //--------------------------------------------------------------------------
                  //  Class methods
                  //--------------------------------------------------------------------------
          
                  

@private Method for creating the Accessibility class. This method is called from UIComponent. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  public static function createAccessibilityImplementation(component:UIComponent):void {
                          component.accessibilityImplementation = new @ax-student-ar-fl-accessibility-ComboBoxAccImpl(component);
                  }
          
                  

Enables accessibility for a ComboBox component. This method is required for the compiler to activate the accessibility classes for a component. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  public static function enableAccessibility():void {
                          ListAccImpl.enableAccessibility();
                  }
                  
                  //--------------------------------------------------------------------------
                  //  Constructor
                  //--------------------------------------------------------------------------
          
          

@private @internal Nivesh says: I don't think we should document the constructors for the accessibility classes. End-users just have to call the static enableAccessibility method. They don't really create an instance of the classes. Creates a new ComboBox Accessibility Implementation.
parameter: master The UIComponent instance that this AccImpl instance is making accessible. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  public function @ax-student-ar-fl-accessibility-ComboBoxAccImpl(master:UIComponent) {
                          super(master);
                          role = 0x2E;
                  }
                  
                  //--------------------------------------------------------------------------
                  //  Overridden properties: AccImpl
                  //--------------------------------------------------------------------------
          
                  

@private Array of events that we should listen for from the master component. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override protected function get eventsToHandle():Array {
                          return super.eventsToHandle.concat([ "change", "valueCommit" ]);
                  }
  
                  //--------------------------------------------------------------------------
                  //  Overridden methods: AccessibilityImplementation
                  //--------------------------------------------------------------------------
          
                  

@private Gets the role for the component.
parameter: childID uint @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function get_accRole(childID:uint):uint {
                          if (childID == 0) {
                                  return role;
                          }
                          return ROLE_SYSTEM_LISTITEM;
                  }
          
                  

@private IAccessible method for returning the value of the ComboBox (which would be the text of the item selected). The ComboBox should return the content of the TextField as the value.
parameter: childID uint
returns: Value string @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function get_accValue(childID:uint):String {
                          if (childID == 0) {
                                  return ComboBox(master).text;
                          }
                          return null;
                  }
          
                  

@private IAccessible method for returning the state of the ListItem (basically to remove 'not selected'). States are predefined for all the components in MSAA. Values are assigned to each state. Depending upon the listItem being Selected, Selectable, Invisible, Offscreen, a value is returned.
parameter: childID
returns: @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function get_accState(childID:uint):uint {
                          var accState:uint = getState(childID);
                          if (childID > 0) {
                                  accState |= STATE_SYSTEM_SELECTABLE;
                                  if (ComboBox(master).selectedIndex == childID - 1) {
                                          accState |= STATE_SYSTEM_SELECTED | STATE_SYSTEM_FOCUSED;
                                  }
                          }
                          return accState;
                  }
          
                  

@private Method to return an array of childIDs. @return @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function getChildIDArray():Array {
                          var childIDs:Array = [];
                          if (ComboBox(master).dataProvider) {
                                  var n:int = ComboBox(master).dataProvider.length;
                                  for (var i:int = 0; i < n; i++) {
                                          childIDs[i] = i + 1;
                                  }
                          }
                          return childIDs;
                  }
          
                  //--------------------------------------------------------------------------
                  //  Overridden methods: AccImpl
                  //--------------------------------------------------------------------------
          
                  

@private Method for returning the name of the ComboBox For children items, it would add m of n string to the name. ComboBox should return the name specified in the AccessibilityProperties.
parameter: childID
returns: @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override protected function getName(childID:uint):String {
                          var comboBox:ComboBox = ComboBox(master);
                          if (childID == 0 || !comboBox.dataProvider) {
                                  return "";
                          }
                          var mofn:String = " " + childID + " of " + comboBox.dataProvider.length;
                          var item:Object = comboBox.getItemAt(childID - 1);
                          return comboBox.itemToLabel(item) + mofn;
                  }
          
                  //--------------------------------------------------------------------------
                  //  Overridden event handlers: AccImpl
                  //--------------------------------------------------------------------------
          
                  

@private Override the generic event handler. All AccImpl must implement this to listen for events from its master component. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override protected function eventHandler(event:Event):void {
                          switch (event.type) {
                                  case "change":
                                          var index:int = ComboBox(master).selectedIndex;
                                          if (index >= 0) {
                                                  if(Accessibility.active) {
                                                          var childID:uint = index + 1;
                                                          Accessibility.sendEvent(master, childID, EVENT_OBJECT_SELECTION);
                                                          Accessibility.sendEvent(master, 0, EVENT_OBJECT_VALUECHANGE);
                                                  }
                                          }
                                          break;
                                  case "valueCommit":
                                          if(Accessibility.active) {
                                                  Accessibility.sendEvent(master, 0, EVENT_OBJECT_VALUECHANGE);
                                          }
                                          break;
                          }
                  }
          }
  }
  

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[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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(C) Æliens 27/08/2009

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