Adobe® Flex® 4 Language Reference
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flash.accessibility 
Accessibility 
Packageflash.accessibility
Classpublic final class Accessibility
InheritanceAccessibility Inheritance Object

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

The Accessibility class manages communication with screen readers. Screen readers are a type of assistive technology for visually impaired users that provides an audio version of screen content. The methods of the Accessibility class are static—that is, you don't have to create an instance of the class to use its methods.

To get and set accessible properties for a specific object, such as a button, movie clip, or text field, use the DisplayObject.accessibilityProperties property. To determine whether the player is running in an environment that supports accessibility aids, use the Capabilities.hasAccessibility property.

Note: AIR 2 supports the JAWS 11 (or higher) screen reader software. For additional information, please see http://www.adobe.com/accessibility/.

View the examples

See also



Public Properties
 PropertyDefined By
  active : Boolean
[static] [read-only] Indicates whether a screen reader is active and the application is communicating with it.
Accessibility
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
Public Methods
 MethodDefined By
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
 Inherited
Returns the string representation of the specified object.
Object
  
[static] Tells Flash Player to apply any accessibility changes made by using the DisplayObject.accessibilityProperties property.
Accessibility
 Inherited
Returns the primitive value of the specified object.
Object
Property Detail

active

property
active:Boolean  [read-only]

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Indicates whether a screen reader is active and the application is communicating with it. Use this method when you want your application to behave differently in the presence of a screen reader.

Once this property is set to true, it remains true for the duration of the application. (It is unusual for a user to turn off the screen reader once it is started.)

Note: Before calling this method, wait 1 or 2 seconds after launching your AIR application or after the first appearance of the Flash® Player window in which your document is playing. Otherwise, you might get a return value of false even if there is an active accessibility client. This happens because of an asynchronous communication mechanism between accessibility clients and Flash Player or AIR.

To determine whether the player is running in an environment that supports screen readers, use the Capabilities.hasAccessibility property.



Implementation
    public static function get active():Boolean

See also

Method Detail

updateProperties

()method
public static function updateProperties():void

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Tells Flash Player to apply any accessibility changes made by using the DisplayObject.accessibilityProperties property. You need to call this method for your changes to take effect.

If you modify the accessibility properties for multiple objects, only one call to the Accessibility.updateProperties() method is necessary; multiple calls can result in reduced performance and erroneous screen reader output.


Throws
IllegalOperationError — Accessibility is not supported in this version of Flash Player. Do not call the Accessibility.updateProperties() method if the flash.system.Capabilities.hasAccessibility property is false.

See also

AccessibilityExample.as

The following example uses AccessibilityExample, CustomAccessibleButton, CustomSimpleButton, and ButtonDisplayState sample classes to create an accessibility-compliant menu that works with most screen readers. The example carries out the following tasks:
  1. It traces the Accessibility.active property to determine whether a screen reader is currently active and the player is communicating with it.
  2. If the active property returns true, the example calls the updateProperties() method to apply the accessibility changes made to the buttons in this example.
  3. The example calls the flash.utils.setTimeout() method, specifying that the updateAccessibility() closure method should be called after 2 seconds.

Note: Call setTimeout() before checking Accessibility.active to give Flash Player the 2 seconds it needs to connect to a screen reader if one is available. If you do not supply a sufficient delay time, the setTimeout call might return false even if a screen reader is available.

The following example processes the Accessibility.updateProperties() method only if the call to Accessibility.active returns true, which occurs only if Flash Player is currently connected to an active screen reader. If updateProperties is called without an active screen reader, it throws an IllegalOperationError exception.

package {
    import flash.display.Sprite;
    import flash.accessibility.Accessibility;
    import flash.utils.setTimeout;
    
    public class AccessibilityExample extends Sprite {
        public static const BUTTON_WIDTH:uint = 90;
        public static const BUTTON_HEIGHT:uint = 20;
        
        private var gutter:uint = 5;
        private var menuLabels:Array = new Array("PROJECTS", "PORTFOLIO", "CONTACT");
        private var menuDescriptions:Array = new Array("Learn more about our projects"
                                                     , "See our portfolio"
                                                     , "Get in touch with our team");
        
        public function AccessibilityExample() {
            configureAssets();
            setTimeout(updateAccessibility, 2000); 
        }
        
        private function updateAccessibility():void {
            trace("Accessibility.active: " + Accessibility.active);
            if(Accessibility.active) {
                Accessibility.updateProperties();
            }
        }
        
        private function configureAssets():void {
            var child:CustomAccessibleButton;
            for(var i:uint; i < menuLabels.length; i++) {
                child = new CustomAccessibleButton();
                child.y = (numChildren * (BUTTON_HEIGHT + gutter));
                child.setLabel(menuLabels[i]);
                child.setDescription(menuDescriptions[i]);
                addChild(child);
            }
        }
    }
}
    
import flash.accessibility.AccessibilityProperties;
import flash.display.Shape;
import flash.display.SimpleButton;
import flash.display.Sprite;
import flash.events.Event;
import flash.text.TextFormat;
import flash.text.TextField;


class CustomAccessibleButton extends Sprite {
    private var button:SimpleButton;
    private var label:TextField;
    private var description:String;
    private var _name:String;
        
    public function CustomAccessibleButton(_width:uint = 0, _height:uint = 0) {
        _width = (_width == 0) ? AccessibilityExample.BUTTON_WIDTH : _width;
        _height = (_height == 0) ? AccessibilityExample.BUTTON_HEIGHT : _height;
        
        button = buildButton(_width, _height);
        label = buildLabel(_width, _height);
            
        addEventListener(Event.ADDED, addedHandler);
    }
        
    private function addedHandler(event:Event):void {
        trace("addedHandler: " + this._name);
        var accessProps:AccessibilityProperties = new AccessibilityProperties();
        accessProps.name = this._name;
        accessProps.description = description;
        accessibilityProperties = accessProps;
        removeEventListener(Event.ADDED, addedHandler);
    }
        
    private function buildButton(_width:uint, _height:uint):SimpleButton {
        var child:SimpleButton = new CustomSimpleButton(_width, _height);
        addChild(child);
        return child;
    }

    private function buildLabel(_width:uint, _height:uint):TextField {
        var format:TextFormat = new TextFormat();
        format.font = "Verdana";
        format.size = 11;
        format.color = 0xFFFFFF;
        format.align = TextFormatAlign.CENTER;
        format.bold = true;
        
        var child:TextField = new TextField();
        child.y = 1;
        child.width = _width;
        child.height = _height;
        child.selectable = false;
        child.defaultTextFormat = format;
        child.mouseEnabled = false;
            
        addChild(child);
        return child;
    }
        
    public function setLabel(text:String):void {
        label.text = text;
        this._name = text;
    }
        
    public function setDescription(text:String):void {
        description = text;
    }
}
    
class CustomSimpleButton extends SimpleButton {
    private var upColor:uint = 0xFFCC00;
    private var overColor:uint = 0xCCFF00;
    private var downColor:uint = 0x00CCFF;

    public function CustomSimpleButton(_width:uint, _height:uint) {
        downState = new ButtonDisplayState(downColor, _width, _height);
        overState = new ButtonDisplayState(overColor, _width, _height);
        upState = new ButtonDisplayState(upColor, _width, _height);
        hitTestState = new ButtonDisplayState(upColor, _width, _height);
        useHandCursor = true;
    }        
}

class ButtonDisplayState extends Shape {
    private var bgColor:uint;
    private var _width:uint;
    private var _height:uint;

    public function ButtonDisplayState(bgColor:uint, _width:uint, _height:uint) {
        this.bgColor = bgColor;
        this._width = _width;
        this._height = _height;
        draw();
    }

    private function draw():void {
        graphics.beginFill(bgColor);
        graphics.drawRect(0, 0, _width, _height);
        graphics.endFill();
    }
}