// Copyright 2007. Adobe Systems Incorporated. All Rights Reserved.
package fl.accessibility {

	import fl.controls.RadioButton;
	import fl.core.UIComponent;
	
	/**
	 * The RadioButtonAccImpl class, also called the RadioButton Accessibility Implementation class,
	 * is used to make a RadioButton component accessible. This class enables communication
	 * between a RadioButton component and a screen reader. Screen readers are used to translate
	 * screen content into synthesized speech or braille for visually impaired users. 
	 * 
	 * <p>The RadioButtonAccImpl class supports system roles, object-based events, and states.</p>
	 * 
	 * <p>A RadioButton reports the role <code>ROLE_SYSTEM_RADIOBUTTON</code> (0x2D) to a screen 
	 * reader.</p>
     *
	 * <p>A RadioButton 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>A RadioButton 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.RadioButton RadioButton
     *
     * @langversion 3.0
     * @playerversion Flash 9.0.28.0
	 */
	public class RadioButtonAccImpl extends CheckBoxAccImpl {
		/**
		 *  @private
         *  Static variable triggering the <code>hookAccessibility()</code> method.
		 *  This is used for initializing CheckBoxAccImpl class to hook its
         *  <code>createAccessibilityImplementation()</code> method to CheckBox 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 CheckBox with the CheckBoxAccImpl class.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static function hookAccessibility():Boolean {
			RadioButton.createAccessibilityImplementation = createAccessibilityImplementation;
			return true;
		}
	
		//--------------------------------------------------------------------------
		//  Class methods
		//--------------------------------------------------------------------------
	
		/**
		 *  @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.accessibilityImplementation = new RadioButtonAccImpl(component);
		}
	
		/**
         *  Enables accessibility for a RadioButton 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 RadioButtonAccImpl instance for the specified RadioButton component.
		 *
		 *  @param master The RadioButton instance that this AccImpl instance
         *         makes accessible.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		public function RadioButtonAccImpl(master:UIComponent) {
			super(master);
			role = 0x2D;
		}
	}
}