// Copyright 2007. Adobe Systems Incorporated. All Rights Reserved.
  package fl.accessibility {
          
          import flash.accessibility.Accessibility;
          import flash.events.Event;
          import flash.events.KeyboardEvent;
          import flash.ui.Keyboard;
          import fl.controls.LabelButton;
          import fl.core.UIComponent;
          import fl.events.ComponentEvent;
          
          

The @ax-student-ar-fl-accessibility-LabelButtonAccImpl class, also called the LabelButton Accessibility Implementation class, is used to make a LabelButton component accessible. This class enables communication between a LabelButton component and a screen reader. Screen readers are used to translate screen content into synthesized speech or braille for visually impaired users. <p>The @ax-student-ar-fl-accessibility-LabelButtonAccImpl class supports system roles, object-based events, and states.</p> <p>A LabelButton reports the role <code>ROLE_SYSTEM_PUSHBUTTON</code> (0x2B) to a screen reader.</p> <p>A LabelButton 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_FOCUSABLE</code> (0x00100000)</li> </ul> <p>A LabelButton dispatches the following events to a screen reader:</p> <ul> <li><code>EVENT_OBJECT_STATECHANGE</code> (0x800A)</li> <li><code>EVENT_OBJECT_NAMECHANGE</code> (0x800C)</li> </ul>
see: fl.controls.LabelButton LabelButton @langversion 3.0 @playerversion Flash 9.0.28.0

  
          public class @ax-student-ar-fl-accessibility-LabelButtonAccImpl extends AccImpl {
                  

@private Static variable triggering the <code>hookAccessibility()</code> method. This is used for initializing @ax-student-ar-fl-accessibility-LabelButtonAccImpl class to hook its <code>createAccessibilityImplementation()</code> method to LabelButton 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 LabelButton with the @ax-student-ar-fl-accessibility-LabelButtonAccImpl class. @langversion 3.0 @playerversion Flash 9.0.28.0

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

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const STATE_SYSTEM_PRESSED:uint = 0x00000008;
          
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const EVENT_OBJECT_NAMECHANGE:uint = 0x800C;
                  
                  

@private @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  private static const EVENT_OBJECT_STATECHANGE:uint = 0x800A;
                  
                  //--------------------------------------------------------------------------
                  //  Class methods
                  //--------------------------------------------------------------------------
          
                  

@private Method for creating the Accessibility class. This method is called from UIComponent.
parameter: component The UIComponent instance that this AccImpl instance is making accessible. @langversion 3.0 @playerversion Flash 9.0.28.0

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

Enables accessibility for a LabelButton 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 {
                  }
          
                  //--------------------------------------------------------------------------
                  //  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 @ax-student-ar-fl-accessibility-LabelButtonAccImpl instance for the specified LabelButton component.
parameter: component The LabelButton instance that this @ax-student-ar-fl-accessibility-LabelButtonAccImpl instance makes accessible. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  public function @ax-student-ar-fl-accessibility-LabelButtonAccImpl(component:UIComponent) {
                          super(component);
                          role = 0x2B;
                  }
          
                  //--------------------------------------------------------------------------
                  //  Overridden properties: AccImpl
                  //--------------------------------------------------------------------------
          
                  

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

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

@private IAccessible method for returning the state of the LabelButton. States are predefined for all the components in MSAA. Values are assigned to each state. Depending upon the button being pressed or released, a value is returned.
parameter: childID The child id.
returns: State. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function get_accState(childID:uint):uint {
                          var accState:uint = getState(childID);
                          if (LabelButton(master).selected) {
                                  accState |= STATE_SYSTEM_PRESSED;
                          }
                          
                          return accState;
                  }
          
                  

@private IAccessible method for returning the default action of the LabelButton, which is Press.
parameter: childID The child id
returns: DefaultAction @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function get_accDefaultAction(childID:uint):String {
                          return "Press";
                  }
          
                  

@private IAccessible method for performing the default action associated with LabelButton, which is Press.
parameter: childID The child id. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override public function accDoDefaultAction(childID:uint):void {
                          
                          
                          if (master.enabled) {
                                  var event:KeyboardEvent = new KeyboardEvent(KeyboardEvent.KEY_DOWN);
                                  event.keyCode = Keyboard.SPACE;
                                  master.dispatchEvent(event);
                                  
                                  event = new KeyboardEvent(KeyboardEvent.KEY_UP);
                                  event.keyCode = Keyboard.SPACE;
                                  master.dispatchEvent(event);
                          }
                  }
                  
                  //--------------------------------------------------------------------------
                  //  Overridden methods: AccImpl
                  //--------------------------------------------------------------------------
          
                  

@private method for returning the name of the LabelButton which is spoken out by the screen reader The LabelButton should return the label inside as the name of the LabelButton. The name returned here would take precedence over the name specified in the Accessibility panel.
parameter: childID The child id.
returns: Name. @langversion 3.0 @playerversion Flash 9.0.28.0

  
                  override protected function getName(childID:uint):String {
                          var label:String = LabelButton(master).label;
                          return label != null && label != "" ? label : "";
                  }
          
                  //--------------------------------------------------------------------------
                  //  Overridden event handlers: AccImpl
                  //--------------------------------------------------------------------------
          
                  

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

  
                  override protected function eventHandler(event:Event):void {
                          switch (event.type) {
                                  case ComponentEvent.BUTTON_DOWN:
                                          
                                          if(Accessibility.active) {
                                                  Accessibility.sendEvent(master, 0, EVENT_OBJECT_STATECHANGE);
                                                  Accessibility.updateProperties();
                                          }
                                          break;
                                  case ComponentEvent.LABEL_CHANGE:
                                          
                                          if(Accessibility.active) {
                                                  Accessibility.sendEvent(master, 0, EVENT_OBJECT_NAMECHANGE);
                                                  Accessibility.updateProperties();
                                          }
                                          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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