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Commit 38e8b4e5 authored by Svetoslav Ganov's avatar Svetoslav Ganov
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Updating accessibility documentation.

Change-Id: Ice8cf9ac6918b3bfa553776c68d4619fa6559cf8
parent f1bfa84c
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+155 −110
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@@ -31,70 +31,86 @@ import android.view.accessibility.AccessibilityNodeInfo;
 * An accessibility service runs in the background and receives callbacks by the system
 * when {@link AccessibilityEvent}s are fired. Such events denote some state transition
 * in the user interface, for example, the focus has changed, a button has been clicked,
 * etc.
 * etc. Such a service can optionally request the capability for querying the content
 * of the active window. Development of an accessibility service requires extends this
 * class and implements its abstract methods.
 * <p>
 * An accessibility service extends this class and implements its abstract methods. Such
 * a service is declared as any other service in an AndroidManifest.xml but it must also
 * specify that it handles the "android.accessibilityservice.AccessibilityService"
 * {@link android.content.Intent}. Following is an example of such a declaration:
 * <p>
 * <code>
 * &lt;service android:name=".MyAccessibilityService"&gt;<br>
 * &nbsp;&nbsp;&lt;intent-filter&gt;<br>
 * &nbsp;&nbsp;&nbsp;&nbsp;&lt;action android:name="android.accessibilityservice.AccessibilityService" /&gt;<br>
 * &nbsp;&nbsp;&lt;/intent-filter&gt;<br>
 * &lt;/service&gt;<br>
 * </code>
 * <strong>Lifecycle</strong>
 * </p>
 * <p>
 * The lifecycle of an accessibility service is managed exclusively by the system. Starting
 * or stopping an accessibility service is triggered by an explicit user action through
 * The lifecycle of an accessibility service is managed exclusively by the system and
 * follows the established service life cycle. Additionally, starting or stopping an
 * accessibility service is triggered exclusively by an explicit user action through
 * enabling or disabling it in the device settings. After the system binds to a service it
 * calls {@link AccessibilityService#onServiceConnected()}. This method can be
 * overriden by clients that want to perform post binding setup.
 * </p>
 * <p>
 * <strong>Declaration</strong>
 * </p>
 * <p>
 * An accessibility is declared as any other service in an AndroidManifest.xml but it
 * must also specify that it handles the "android.accessibilityservice.AccessibilityService"
 * {@link android.content.Intent}. Failure to declare this intent will cause the system to
 * ignore the accessibility service. Following is an example declaration:
 * </p>
 * <p>
 * <code>
 * <pre>
 *   &lt;service android:name=".MyAccessibilityService"&gt;
 *     &lt;intent-filter&gt;
 *       &lt;action android:name="android.accessibilityservice.AccessibilityService" /&gt;
 *     &lt;/intent-filter&gt;
 *     . . .
 *   &lt;/service&gt;
 * </pre>
 * </code>
 * </p>
 * <p>
 * <strong>Configuration</strong>
 * </p>
 * <p>
 * An accessibility service can be configured to receive specific types of accessibility events,
 * listen only to specific packages, get events from each type only once in a given time frame,
 * retrieve window content, specify a settings activity, etc.
 * </p>
 * <p>
 * There are two approaches for configuring an accessibility service:
 * </p>
 * <ul>
 * <li>
 * Providing a {@link #SERVICE_META_DATA meta-data} entry in the manifest when declaring
 * the service. A service declaration with a meta-data tag is presented below:
 * <p>
 * <code>
 *         &lt;service android:name=".MyAccessibilityService"&gt;<br>
 *         &nbsp;&nbsp;&lt;intent-filter&gt;<br>
 *         &nbsp;&nbsp;&nbsp;&nbsp;&lt;action android:name="android.accessibilityservice.AccessibilityService" /&gt;<br>
 *         &nbsp;&nbsp;&lt;/intent-filter&gt;<br>
 *         &nbsp;&nbsp;&lt;meta-data android:name="android.accessibilityservice.as" android:resource="@xml/accessibilityservice" /&gt;<br>
 *         &lt;/service&gt;<br>
 * <pre>
 *   &lt;service android:name=".MyAccessibilityService"&gt;
 *     &lt;intent-filter&gt;
 *       &lt;action android:name="android.accessibilityservice.AccessibilityService" /&gt;
 *     &lt;/intent-filter&gt;
 *     &lt;meta-data android:name="android.accessibilityservice" android:resource="@xml/accessibilityservice" /&gt;
 *   &lt;/service&gt;
 * </pre>
 * </code>
 * </p>
 * <p>
 *     <strong>
 *       This approach enables setting all accessibility service properties.
 *     </strong>
 * <strong>Note:</strong>This approach enables setting all properties.
 * </p>
 * <p>
 *       For more details refer to {@link #SERVICE_META_DATA}.
 * For more details refer to {@link #SERVICE_META_DATA} and
 * <code>&lt;{@link android.R.styleable#AccessibilityService accessibility-service}&gt;</code>..
 * </p>
 * </li>
 * <li>
 * Calling {@link AccessibilityService#setServiceInfo(AccessibilityServiceInfo)}. Note
 *     that this method can be called any time to change the service configuration.<br>
 * that this method can be called any time to dynamically change the service configuration.
 * <p>
 *     <strong>
 *       This approach enables setting only dynamically configurable accessibility
 *       service properties:
 * <strong>Note:</strong> This approach enables setting only dynamically configurable properties:
 * {@link AccessibilityServiceInfo#eventTypes},
 * {@link AccessibilityServiceInfo#feedbackType},
 * {@link AccessibilityServiceInfo#flags},
 * {@link AccessibilityServiceInfo#notificationTimeout},
 * {@link AccessibilityServiceInfo#packageNames}
 *     </strong>
 * </p>
 * <p>
 * For more details refer to {@link AccessibilityServiceInfo}.
@@ -102,11 +118,64 @@ import android.view.accessibility.AccessibilityNodeInfo;
 * </li>
 * </ul>
 * <p>
 * An accessibility service can be registered for events in specific packages to provide a
 * specific type of feedback and is notified with a certain timeout after the last event
 * of interest has been fired.
 * <strong>Retrieving window content</strong>
 * </p>
 * <p>
 * An service can specify in its declaration that it can retrieve the active window
 * content which is represented as a tree of {@link AccessibilityNodeInfo}. Note that
 * declaring this capability requires that the service declares its configuration via
 * an XML resource referenced by {@link #SERVICE_META_DATA}.
 * </p>
 * <p>
 * For security purposes an accessibility service can retrieve only the content of the
 * currently active window. The currently active window is defined as the window from
 * which was fired the last event of the following types:
 * {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_START},
 * {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_END},
 * {@link AccessibilityEvent#TYPE_VIEW_CLICKED},
 * {@link AccessibilityEvent#TYPE_VIEW_FOCUSED},
 * {@link AccessibilityEvent#TYPE_VIEW_HOVER_ENTER},
 * {@link AccessibilityEvent#TYPE_VIEW_HOVER_EXIT},
 * {@link AccessibilityEvent#TYPE_VIEW_LONG_CLICKED},
 * {@link AccessibilityEvent#TYPE_VIEW_SELECTED},
 * {@link AccessibilityEvent#TYPE_VIEW_TEXT_CHANGED},
 * {@link AccessibilityEvent#TYPE_WINDOW_STATE_CHANGED},
 * {@link AccessibilityEvent#TYPE_VIEW_SCROLLED},
 * {@link AccessibilityEvent#TYPE_VIEW_TEXT_SELECTION_CHANGED},
 * {@link AccessibilityEvent#TYPE_WINDOW_CONTENT_CHANGED}.
 * In other words, the active window is the one where the user interaction is taking place.
 * </p>
 * <p>
 * The entry point for retrieving window content is through calling
 * {@link AccessibilityEvent#getSource() AccessibilityEvent.getSource()} of the last received
 * event of the above types or a previous event from the same window
 * (see {@link AccessibilityEvent#getWindowId() AccessibilityEvent.getWindowId()}). Invoking
 * this method will return an {@link AccessibilityNodeInfo} that can be used to traverse the
 * window content which represented as a tree of such objects.
 * </p>
 * <p>
 * <strong>Note</strong>An accessibility service may have requested to be notified for
 * a subset of the event types, thus be unaware that the active window has changed. Therefore
 * accessibility service that would like to retrieve window content should:
 * <ul>
 * <li>
 * Register for all event types with no notification timeout and keep track for the active
 * window by calling {@link AccessibilityEvent#getWindowId()} of the last received event and
 * compare this with the {@link AccessibilityNodeInfo#getWindowId()} before calling retrieval
 * methods on the latter.
 * </li>
 * <li>
 * Prepare that a retrieval method on {@link AccessibilityNodeInfo} may fail since the
 * active window has changed and the service did not get the accessibility event yet. Note
 * that it is possible to have a retrieval method failing event adopting the strategy
 * specified in the previous bullet because the accessibility event dispatch is asynchronous
 * and crosses process boundaries.
 * </li>
 * </ul>
 * </p>
 * <p>
 * <b>Notification strategy</b>
 * </p>
 * <p>
 * For each feedback type only one accessibility service is notified. Services are notified
 * in the order of registration. Hence, if two services are registered for the same
@@ -117,9 +186,10 @@ import android.view.accessibility.AccessibilityNodeInfo;
 * registration order. This enables "generic" accessibility services that work reasonably
 * well with most applications to coexist with "polished" ones that are targeted for
 * specific applications.
 * </p>
 * <p>
 * <b>Event types</b>
 * <p>
 * </p>
 * {@link AccessibilityEvent#TYPE_VIEW_CLICKED}
 * {@link AccessibilityEvent#TYPE_VIEW_LONG_CLICKED}
 * {@link AccessibilityEvent#TYPE_VIEW_FOCUSED}
@@ -127,6 +197,13 @@ import android.view.accessibility.AccessibilityNodeInfo;
 * {@link AccessibilityEvent#TYPE_VIEW_TEXT_CHANGED}
 * {@link AccessibilityEvent#TYPE_WINDOW_STATE_CHANGED}
 * {@link AccessibilityEvent#TYPE_NOTIFICATION_STATE_CHANGED}
 * {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_START}
 * {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_END}
 * {@link AccessibilityEvent#TYPE_VIEW_HOVER_ENTER}
 * {@link AccessibilityEvent#TYPE_VIEW_HOVER_EXIT}
 * {@link AccessibilityEvent#TYPE_VIEW_SCROLLED}
 * {@link AccessibilityEvent#TYPE_VIEW_TEXT_SELECTION_CHANGED}
 * {@link AccessibilityEvent#TYPE_WINDOW_CONTENT_CHANGED}
 * <p>
 * <b>Feedback types</b>
 * <p>
@@ -140,10 +217,10 @@ import android.view.accessibility.AccessibilityNodeInfo;
 * @see AccessibilityServiceInfo
 * @see android.view.accessibility.AccessibilityManager
 *
 * Note: The event notification timeout is useful to avoid propagating events to the client
 *       too frequently since this is accomplished via an expensive interprocess call.
 *       One can think of the timeout as a criteria to determine when event generation has
 *       settled down.
 * <strong>Note:</strong> The event notification timeout is useful to avoid propagating
 * events to the client too frequently since this is accomplished via an expensive
 * interprocess call. One can think of the timeout as a criteria to determine when
 * event generation has settled down.
 */
public abstract class AccessibilityService extends Service {
    /**
@@ -154,57 +231,25 @@ public abstract class AccessibilityService extends Service {

    /**
     * Name under which an AccessibilityService component publishes information
     * about itself. This meta-data must reference an XML resource containing
     * an
     * about itself. This meta-data must reference an XML resource containing an
     * <code>&lt;{@link android.R.styleable#AccessibilityService accessibility-service}&gt;</code>
     * tag. This is a a sample XML file configuring an accessibility service:
     * <p>
     * <code>
     *   &lt;?xml version="1.0" encoding="utf-8"?&gt;<br>
     *   &lt;accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"<br>
     *   &nbsp;&nbsp;android:accessibilityEventTypes="typeViewClicked|typeViewFocused"<br>
     *   &nbsp;&nbsp;android:packageNames="foo.bar, foo.baz"<br>
     *   &nbsp;&nbsp;android:accessibilityFeedbackType="feedbackSpoken"<br>
     *   &nbsp;&nbsp;android:notificationTimeout="100"<br>
     *   &nbsp;&nbsp;android:accessibilityFlags="flagDefault"<br>
     *   &nbsp;&nbsp;android:settingsActivity="foo.bar.TestBackActivity"<br>
     *   &nbsp;&nbsp;. . .<br>
     * <pre>
     *   &lt;accessibility-service
     *     android:accessibilityEventTypes="typeViewClicked|typeViewFocused"
     *     android:packageNames="foo.bar, foo.baz"
     *     android:accessibilityFeedbackType="feedbackSpoken"
     *     android:notificationTimeout="100"
     *     android:accessibilityFlags="flagDefault"
     *     android:settingsActivity="foo.bar.TestBackActivity"
     *     android:canRetrieveWindowContent="true"
     *     . . .
     *   /&gt;
     * </pre>
     * </code>
     * </p>
     * <p>
     *  <strong>Note:</strong> A service can retrieve only the content of the active window.
     *          An active window is the source of the most recent event of type
     *          {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_START},
     *          {@link AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_END},
     *          {@link AccessibilityEvent#TYPE_VIEW_CLICKED},
     *          {@link AccessibilityEvent#TYPE_VIEW_FOCUSED},
     *          {@link AccessibilityEvent#TYPE_VIEW_HOVER_ENTER},
     *          {@link AccessibilityEvent#TYPE_VIEW_HOVER_EXIT},
     *          {@link AccessibilityEvent#TYPE_VIEW_LONG_CLICKED},
     *          {@link AccessibilityEvent#TYPE_VIEW_SELECTED},
     *          {@link AccessibilityEvent#TYPE_VIEW_TEXT_CHANGED},
     *          {@link AccessibilityEvent#TYPE_WINDOW_STATE_CHANGED}.
     *          Therefore the service should:
     *          <ul>
     *            <li>
     *              Register for all event types with no notification timeout and keep track
     *              for the active window by calling
     *              {@link AccessibilityEvent#getWindowId()} of the last received
     *              event and compare this with the
     *              {@link AccessibilityNodeInfo#getWindowId()} before calling
     *              retrieval methods on the latter.
     *            </li>
     *            <li>
     *              Prepare that a retrieval method on {@link AccessibilityNodeInfo} may fail
     *              since the active window has changed and the service did not get the 
     *              accessibility event. Note that it is possible to have a retrieval method
     *              failing event adopting the strategy specified in the previous bullet
     *              because the accessibility event dispatch is asynchronous and crosses
     *              process boundaries. 
     *            </li>
     *          <ul>
     * </p>
     */
    public static final String SERVICE_META_DATA = "android.accessibilityservice";

+18 −11
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@@ -37,13 +37,13 @@ import org.xmlpull.v1.XmlPullParserException;
import java.io.IOException;

/**
 * This class describes an {@link AccessibilityService}. The system
 * notifies an {@link AccessibilityService} for
 * {@link android.view.accessibility.AccessibilityEvent}s
 * This class describes an {@link AccessibilityService}. The system notifies an
 * {@link AccessibilityService} for {@link android.view.accessibility.AccessibilityEvent}s
 * according to the information encapsulated in this class.
 *
 * @see AccessibilityService
 * @see android.view.accessibility.AccessibilityEvent
 * @see android.view.accessibility.AccessibilityManager
 */
public class AccessibilityServiceInfo implements Parcelable {

@@ -93,12 +93,19 @@ public class AccessibilityServiceInfo implements Parcelable {
     * @see android.view.accessibility.AccessibilityEvent#TYPE_VIEW_TEXT_CHANGED
     * @see android.view.accessibility.AccessibilityEvent#TYPE_WINDOW_STATE_CHANGED
     * @see android.view.accessibility.AccessibilityEvent#TYPE_NOTIFICATION_STATE_CHANGED
     * @see android.view.accessibility.AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_START
     * @see android.view.accessibility.AccessibilityEvent#TYPE_TOUCH_EXPLORATION_GESTURE_END
     * @see android.view.accessibility.AccessibilityEvent#TYPE_VIEW_HOVER_ENTER
     * @see android.view.accessibility.AccessibilityEvent#TYPE_VIEW_HOVER_EXIT
     * @see android.view.accessibility.AccessibilityEvent#TYPE_VIEW_SCROLLED
     * @see android.view.accessibility.AccessibilityEvent#TYPE_VIEW_TEXT_SELECTION_CHANGED
     * @see android.view.accessibility.AccessibilityEvent#TYPE_WINDOW_CONTENT_CHANGED
     */
    public int eventTypes;

    /**
     * The package names an {@link AccessibilityService} is interested in. Setting
     * to null is equivalent to all packages.
     * to <code>null</code> is equivalent to all packages.
     * <p>
     *   <strong>Can be dynamically set at runtime.</strong>
     * </p>
@@ -125,10 +132,10 @@ public class AccessibilityServiceInfo implements Parcelable {
     *   <strong>Can be dynamically set at runtime.</strong>.
     * </p>
     * <p>
     * Note: The event notification timeout is useful to avoid propagating events to the client
     *       too frequently since this is accomplished via an expensive interprocess call.
     *       One can think of the timeout as a criteria to determine when event generation has
     *       settled down
     * <strong>Note:</strong> The event notification timeout is useful to avoid propagating
     *       events to the client too frequently since this is accomplished via an expensive
     *       interprocess call. One can think of the timeout as a criteria to determine when
     *       event generation has settled down.
     */
    public long notificationTimeout;

@@ -159,7 +166,7 @@ public class AccessibilityServiceInfo implements Parcelable {
    private String mSettingsActivityName;

    /**
     * Flag whether this accessibility service can retrieve screen content.
     * Flag whether this accessibility service can retrieve window content.
     */
    private boolean mCanRetrieveWindowContent;

@@ -296,12 +303,12 @@ public class AccessibilityServiceInfo implements Parcelable {
    }

    /**
     * Whether this service can retrieve the currently focused window content.
     * Whether this service can retrieve the current window's content.
     * <p>
     *    <strong>Statically set from
     *    {@link AccessibilityService#SERVICE_META_DATA meta-data}.</strong>
     * </p>
     * @return True screen content is retrieved.
     * @return True window content can be retrieved.
     */
    public boolean getCanRetrieveWindowContent() {
        return mCanRetrieveWindowContent;
+22 −0
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<html>
<body>
<p>
  The classes in this package are used for development of accessibility service that
  provide alternative or augmented feedback to the user.
</p>
<p>
  An {@link android.accessibilityservice.AccessibilityService} runs in the background and
  receives callbacks by the system when {@link android.view.accessibility.AccessibilityEvent}s
  are fired. Such events denote some state transition in the user interface, for example, the
  focus has changed, a button has been clicked, etc. Such a service can optionally request the
  capability for querying the content of the active window. Development of an accessibility
  service requires extends this class and implements its abstract methods.
</p>
<p>
  An {@link android.accessibilityservice.AccessibilityServiceInfo} describes an
  {@link android.accessibilityservice.AccessibilityService}. The system notifies an
  AccessibilityService for {@link android.view.accessibility.AccessibilityEvent}s
  according to the information encapsulated in this class.
</p>
</body>
</html>
+111 −77

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+8 −6
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@@ -24,11 +24,12 @@ public interface AccessibilityEventSource {
    /**
     * Handles the request for sending an {@link AccessibilityEvent} given
     * the event type. The method must first check if accessibility is on
     * via calling {@link AccessibilityManager#isEnabled()}, obtain
     * an {@link AccessibilityEvent} from the event pool through calling
     * {@link AccessibilityEvent#obtain(int)}, populate the event, and
     * send it for dispatch via calling
     * {@link AccessibilityManager#sendAccessibilityEvent(AccessibilityEvent)}.
     * via calling {@link AccessibilityManager#isEnabled() AccessibilityManager.isEnabled()},
     * obtain an {@link AccessibilityEvent} from the event pool through calling
     * {@link AccessibilityEvent#obtain(int) AccessibilityEvent.obtain(int)}, populate the
     * event, and send it for dispatch via calling
     * {@link AccessibilityManager#sendAccessibilityEvent(AccessibilityEvent)
     * AccessibilityManager.sendAccessibilityEvent(AccessibilityEvent)}.
     *
     * @see AccessibilityEvent
     * @see AccessibilityManager
@@ -41,7 +42,8 @@ public interface AccessibilityEventSource {
     * Handles the request for sending an {@link AccessibilityEvent}. The
     * method does not guarantee to check if accessibility is on before
     * sending the event for dispatch. It is responsibility of the caller
     * to do the check via calling {@link AccessibilityManager#isEnabled()}.
     * to do the check via calling {@link AccessibilityManager#isEnabled()
     * AccessibilityManager.isEnabled()}.
     *
     * @see AccessibilityEvent
     * @see AccessibilityManager
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