Types of Accessibility
Accessible components can export several types of
assistive functionalities—for example: actions, text properties,
component properties, icon properties, selections, table properties,
hypertext, and bounded-range value properties. Most of these functions
are already present in the Swing components, so if you stick closely to
Swing, you probably won’t need to implement these interfaces in your
components. In an effort to explain how one might implement these
interfaces, we have provided a simple example showing how to add
AccessibleAction support to an
AWT-based component.
The AccessibleAction Interface
The AccessibleAction
interface outlines the methods that an accessible
object or component must have to export its actions. The idea is that
an assistive technology can determine the correct action by obtaining
the total number of actions that the component exports, then reviewing
each of their descriptions to resolve the correct one. Once this has
occurred, the doAccessibleAction( )
method can be called with the correct index to invoke the required
method.
Properties
The properties in Table
25-5 must be readable through the AccessibleAction interface. accessibleActionCount stores the number of
accessible actions that the component implements. The indexed
property accessibleActionDescription provides a
string describing the action associated with the given index. The
action with index 0 is the component’s default action.
Table 25-5. AccessibleAction properties ...