// Copyright 2007. Adobe Systems Incorporated. All Rights Reserved.
package fl.accessibility {
	
	import flash.accessibility.Accessibility;
	import flash.accessibility.AccessibilityProperties;
	import fl.controls.ScrollBar;
	import fl.core.UIComponent;
	import flash.events.Event;
	
	/**
	 * The UIComponentAccImpl class, also called the UIComponent Accessibility Implementation class,
	 * is used to make a UIComponent accessible. This class enables communication
	 * between a List-based component and a screen reader. Screen readers are used to translate
	 * screen content into synthesized speech or braille for visually impaired users.
	 * 
	 * <p>The ListAccImpl class supports system roles, object-based events, and states.</p>
	 * 
	 * @internal
     * Adobe: Probably just a dup-and-revise error, but this last sentence references the BaseListAccImpl class. 
	 * Probably should refer to the UIComponentAccImpl class?
	 * [CW] the whole description is wrong here. UIComponentAccImpl extends AccessibilityProperties
	 * and not AccessibilityImplementation, and exists purely to wrap the accessibilityProperties 
	 * property of UIComponents (and to make the ScrollBar component silent to screenreaders).
     * 
     * Metaliq: Claus, did you change the description above? I still see a mention of BaseListAccImpl class. (line 15, i changed it to ListAccImpl though)
     *
     * @see fl.core.UIComponent UIComponent
     *
     * @langversion 3.0
     * @playerversion Flash 9.0.28.0
	 */
	public class UIComponentAccImpl extends AccessibilityProperties {
		/**
		 *  @private
         *  Static variable triggering the <code>hookAccessibility()</code> method.
		 *  This is used for initializing UIComponentAccImpl class to hook its
         *  <code>createAccessibilityImplementation()</code> method to UIComponent class 
         *  before it gets called from <code>UIComponent.initialize()</code>.
         *
         * @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 UIComponent with the UIComponentAccImpl class.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static function hookAccessibility():Boolean {
			UIComponent.createAccessibilityImplementation = createAccessibilityImplementation;
			return true;
		}
	
		/**
         *  @private (protected)
         *  A reference to the UIComponent itself.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		protected var master:UIComponent;

		/**
		 *  @private
		 *  Method for creating the Accessibility class.
		 *  This method is called from UIComponent. 
		 * 
		 *  @param 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.accessibilityProperties = new UIComponentAccImpl(component);
		}
		
		/**
         *  Enables accessibility for a UIComponent 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 UIComponentAccImpl instance for the specified UIComponent component.
		 *
		 *  @param master The UIComponent instance that this AccImpl instance
         *  makes accessible.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		public function UIComponentAccImpl(component:UIComponent) {
			super();
			
			master = component;
			
			if (component.accessibilityProperties) {
				silent = component.accessibilityProperties.silent;
				forceSimple = component.accessibilityProperties.forceSimple;
				noAutoLabeling = component.accessibilityProperties.noAutoLabeling;
				if (component.accessibilityProperties.name) {
					name = component.accessibilityProperties.name;
				}
				if (component.accessibilityProperties.description) {
					description = component.accessibilityProperties.description;
				}
				if (component.accessibilityProperties.shortcut) {
					shortcut = component.accessibilityProperties.shortcut;
				}
			}
			
			if (master is ScrollBar) {
				silent = true;
			}
		}

		//--------------------------------------------------------------------------
		//  Event handlers
		//--------------------------------------------------------------------------
	
		/**
         *  @private (protected)
		 *  Generic event handler.
		 *  All UIComponentAccImpl subclasses must implement this
		 *  to listen for events from its master component. 
		 * 
         *  @param event The event object.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		protected function eventHandler(event:Event):void {
		}
	}
}