You can create accessible documents with ActionScript® code. For accessibility properties that apply to the entire document, you can create or modify a global variable called _accProps. See the _accProps property in ActionScript 2.0 Language Reference at www.adobe.com/go/learn_fl_cs4_as2lr_en.

For properties that apply to a specific object, you can use the syntax instancename._accProps. The value of _accProps is an object that can include any of the following properties:

Modifying the _accProps variable has no effect by itself. You must also use the Accessibility.updateProperties method to inform screen reader users of Flash content changes. Calling the method causes Flash Player to re‑examine all accessibility properties, update property descriptions for the screen reader, and, if necessary, send events to the screen reader that indicate changes have occurred.

When updating accessibility properties of multiple objects at once, include only a single call to Accessiblity.updateProperties (too frequent updates to the screen reader can cause some screen readers to become too verbose).

See the Accessibility.updateProperties method in the ActionScript 2.0 Language Reference at www.adobe.com/go/learn_fl_cs4_as2lr_en.

To create Flash content that behaves in a specific way if a screen reader is active, use the Accessibility.isActive() ActionScript method, which returns a value of true if a screen reader is present, and false otherwise. You can then design your Flash content to perform so that it’s compatible with screen reader use (for example, by hiding child elements from the screen reader). For more information, see the Accessibility.isActive method in the ActionScript 2.0 Language Reference at www.adobe.com/go/learn_fl_cs4_as2lr_en.

For example, you could use the Accessibility.isActive() method to decide whether to include unsolicited animation. Unsolicited animation happens without the screen reader doing anything, which can be confusing for screen readers.

The Accessibility.isActive() method provides asynchronous communication between the Flash content and Flash Player; a slight real-time delay can occur between the time the method is called and the time when Flash Player becomes active, returning an incorrect value of false. To ensure that the method is called correctly, do one of the following:

• Instead of using the Accessibility.isActive() method when the Flash content first plays, call the method whenever you need to make a decision about accessibility.

• Introduce a short delay of one or two seconds at the beginning of your document to give the Flash content enough time to contact Flash Player.

  For example, you can use an onFocus event to attach this method to a button. This approach generally gives the SWF file enough time to load and you can assume a screen reader user will tab to the first button or object on the Stage.

A core set of UI components accelerates building accessible applications. These components automate many of the most common accessibility practices related to labeling, keyboard access, and testing and help ensure a consistent user experience across rich applications. Flash includes the following set of accessible components:

• SimpleButton

• CheckBox

• RadioButton

• Label

• TextInput

• TextArea

• ComboBox

• ListBox

• Window

• Alert

• DataGrid

Accessible Flash components must contain ActionScript that defines their accessible behavior. For information on which accessible components work with screen readers, see the Flash Accessibility web page at www.adobe.com/go/flash_accessibility/.

For general information about components, see “About Components” in Using ActionScript 2.0 Components at www.adobe.com/go/go/learn_fl_cs4_as2components_en.

For each accessible component, enable the accessible portion of the component with the enableAccessibility() command. This command includes the accessibility object with the component as the document is compiled. Because no simple way exists to remove an object after it is added to the component, these options are disabled by default. Therefore, it’s important that you enable accessibility for each component. Perform this step only once for each component; you do not need to enable accessibility for each instance of a component for a given document. See “Button component”, “CheckBox component”, “ComboBox component”, “Label component”, “List component”, “RadioButton component”, and “Window component” in the ActionScript 2.0 Components Language Reference at www.adobe.com/go/learn_fl_cs4_as2lr_en.