AccessibilityNodeProvider

public abstract class AccessibilityNodeProvider
extends Object

This class is the contract a client should implement to enable support of a virtual view hierarchy rooted at a given view for accessibility purposes. A virtual view hierarchy is a tree of imaginary Views that is reported as a part of the view hierarchy when an AccessibilityService explores the window content. Since the virtual View tree does not exist this class is responsible for managing the AccessibilityNodeInfos describing that tree to accessibility services.

The main use case of these APIs is to enable a custom view that draws complex content, for example a monthly calendar grid, to be presented as a tree of logical nodes, for example month days each containing events, thus conveying its logical structure.

A typical use case is to override getAccessibilityNodeProvider() of the View that is a root of a virtual View hierarchy to return an instance of this class. In such a case this instance is responsible for managing AccessibilityNodeInfos describing the virtual sub-tree rooted at the View including the one representing the View itself. Similarly the returned instance is responsible for performing accessibility actions on any virtual view or the root view itself. For example:

     getAccessibilityNodeProvider(
         if (mAccessibilityNodeProvider == null) {
             mAccessibilityNodeProvider = new AccessibilityNodeProvider() {
                 public boolean performAction(int action, int virtualDescendantId) {
                     // Implementation.
                     return false;
                 }

                 public List findAccessibilityNodeInfosByText(String text,
                         int virtualDescendantId) {
                     // Implementation.
                     return null;
                 }

                 public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualDescendantId) {
                     // Implementation.
                     return null;
                 }
             });
     return mAccessibilityNodeProvider;
 

Summary

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long millis, int nanos) Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed. final void wait(long millis) Causes the current thread to wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed. final void wait() Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object.

Constants

int HOST_VIEW_ID

Public constructors

AccessibilityNodeProvider ()

Public methods

AccessibilityNodeInfo createAccessibilityNodeInfo (int virtualViewId)

List<AccessibilityNodeInfo> findAccessibilityNodeInfosByText (String text, 
                int virtualViewId)

AccessibilityNodeInfo findFocus (int focus)

boolean performAction (int virtualViewId, 
                int action, 
                Bundle arguments)