https://source.android.com/ 
/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view.accessibility;

import static android.accessibilityservice.AccessibilityServiceInfo.FLAG_ENABLE_ACCESSIBILITY_VOLUME;

import android.Manifest;
import android.accessibilityservice.AccessibilityServiceInfo;
import android.accessibilityservice.AccessibilityServiceInfo.FeedbackType;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.SdkConstant;
import android.annotation.SystemService;
import android.content.ComponentName;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.ServiceInfo;
import android.content.res.Resources;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.Process;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.os.UserHandle;
import android.util.ArrayMap;
import android.util.Log;
import android.util.SparseArray;
import android.view.IWindow;
import android.view.View;
import android.view.accessibility.AccessibilityEvent.EventType;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.util.IntPair;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;


System level service that serves as an event dispatch for AccessibilityEvents, and provides facilities for querying the accessibility state of the system. Accessibility events are generated when something notable happens in the user interface, for example an Activity starts, the focus or selection of a View changes etc. Parties interested in handling accessibility events implement and register an accessibility service which extends AccessibilityService. 
See Also:
/**
 * System level service that serves as an event dispatch for {@link AccessibilityEvent}s,
 * and provides facilities for querying the accessibility state of the system.
 * Accessibility events are generated when something notable happens in the user interface,
 * for example an {@link android.app.Activity} starts, the focus or selection of a
 * {@link android.view.View} changes etc. Parties interested in handling accessibility
 * events implement and register an accessibility service which extends
 * {@link android.accessibilityservice.AccessibilityService}.
 *
 * @see AccessibilityEvent
 * @see AccessibilityNodeInfo
 * @see android.accessibilityservice.AccessibilityService
 * @see Context#getSystemService
 * @see Context#ACCESSIBILITY_SERVICE
 */
@SystemService(Context.ACCESSIBILITY_SERVICE)
public final class AccessibilityManager {
    private static final boolean DEBUG = false;

    private static final String LOG_TAG = "AccessibilityManager";

    
@hide
/** @hide */
    public static final int STATE_FLAG_ACCESSIBILITY_ENABLED = 0x00000001;

    
@hide
/** @hide */
    public static final int STATE_FLAG_TOUCH_EXPLORATION_ENABLED = 0x00000002;

    
@hide
/** @hide */
    public static final int STATE_FLAG_HIGH_TEXT_CONTRAST_ENABLED = 0x00000004;

    
@hide
/** @hide */
    public static final int DALTONIZER_DISABLED = -1;

    
@hide
/** @hide */
    public static final int DALTONIZER_SIMULATE_MONOCHROMACY = 0;

    
@hide
/** @hide */
    public static final int DALTONIZER_CORRECT_DEUTERANOMALY = 12;

    
@hide
/** @hide */
    public static final int AUTOCLICK_DELAY_DEFAULT = 600;

    
Activity action: Launch UI to manage which accessibility service or feature is assigned
to the navigation bar Accessibility button.


Input: Nothing.




Output: Nothing.



@hide
/**
     * Activity action: Launch UI to manage which accessibility service or feature is assigned
     * to the navigation bar Accessibility button.
     * <p>
     * Input: Nothing.
     * </p>
     * <p>
     * Output: Nothing.
     * </p>
     *
     * @hide
     */
    @SdkConstant(SdkConstant.SdkConstantType.ACTIVITY_INTENT_ACTION)
    public static final String ACTION_CHOOSE_ACCESSIBILITY_BUTTON =
            "com.android.internal.intent.action.CHOOSE_ACCESSIBILITY_BUTTON";

    static final Object sInstanceSync = new Object();

    private static AccessibilityManager sInstance;

    private final Object mLock = new Object();

    private IAccessibilityManager mService;

    final int mUserId;

    final Handler mHandler;

    final Handler.Callback mCallback;

    boolean mIsEnabled;

    int mRelevantEventTypes = AccessibilityEvent.TYPES_ALL_MASK;

    boolean mIsTouchExplorationEnabled;

    boolean mIsHighTextContrastEnabled;

    AccessibilityPolicy mAccessibilityPolicy;

    private final ArrayMap<AccessibilityStateChangeListener, Handler>
            mAccessibilityStateChangeListeners = new ArrayMap<>();

    private final ArrayMap<TouchExplorationStateChangeListener, Handler>
            mTouchExplorationStateChangeListeners = new ArrayMap<>();

    private final ArrayMap<HighTextContrastChangeListener, Handler>
            mHighTextContrastStateChangeListeners = new ArrayMap<>();

    private final ArrayMap<AccessibilityServicesStateChangeListener, Handler>
            mServicesStateChangeListeners = new ArrayMap<>();

    
Map from a view's accessibility id to the list of request preparers set for that view

/**
     * Map from a view's accessibility id to the list of request preparers set for that view
     */
    private SparseArray<List<AccessibilityRequestPreparer>> mRequestPreparerLists;

    
Listener for the system accessibility state. To listen for changes to the accessibility state on the device, implement this interface and register it with the system by calling addAccessibilityStateChangeListener. 
/**
     * Listener for the system accessibility state. To listen for changes to the
     * accessibility state on the device, implement this interface and register
     * it with the system by calling {@link #addAccessibilityStateChangeListener}.
     */
    public interface AccessibilityStateChangeListener {

        
Called when the accessibility enabled state changes.

Params:
  • enabled – Whether accessibility is enabled.
/**
         * Called when the accessibility enabled state changes.
         *
         * @param enabled Whether accessibility is enabled.
         */
        void onAccessibilityStateChanged(boolean enabled);
    }

    
Listener for the system touch exploration state. To listen for changes to the touch exploration state on the device, implement this interface and register it with the system by calling addTouchExplorationStateChangeListener. 
/**
     * Listener for the system touch exploration state. To listen for changes to
     * the touch exploration state on the device, implement this interface and
     * register it with the system by calling
     * {@link #addTouchExplorationStateChangeListener}.
     */
    public interface TouchExplorationStateChangeListener {

        
Called when the touch exploration enabled state changes.

Params:
  • enabled – Whether touch exploration is enabled.
/**
         * Called when the touch exploration enabled state changes.
         *
         * @param enabled Whether touch exploration is enabled.
         */
        void onTouchExplorationStateChanged(boolean enabled);
    }

    
Listener for changes to the state of accessibility services. Changes include services being enabled or disabled, or changes to the AccessibilityServiceInfo of a running service. {@see #addAccessibilityServicesStateChangeListener}. 
@hide
/**
     * Listener for changes to the state of accessibility services. Changes include services being
     * enabled or disabled, or changes to the {@link AccessibilityServiceInfo} of a running service.
     * {@see #addAccessibilityServicesStateChangeListener}.
     *
     * @hide
     */
    public interface AccessibilityServicesStateChangeListener {

        
Called when the state of accessibility services changes.

Params:
  • manager – The manager that is calling back
/**
         * Called when the state of accessibility services changes.
         *
         * @param manager The manager that is calling back
         */
        void onAccessibilityServicesStateChanged(AccessibilityManager manager);
    }

    
Listener for the system high text contrast state. To listen for changes to the high text contrast state on the device, implement this interface and register it with the system by calling addHighTextContrastStateChangeListener. 
@hide
/**
     * Listener for the system high text contrast state. To listen for changes to
     * the high text contrast state on the device, implement this interface and
     * register it with the system by calling
     * {@link #addHighTextContrastStateChangeListener}.
     *
     * @hide
     */
    public interface HighTextContrastChangeListener {

        
Called when the high text contrast enabled state changes.

Params:
  • enabled – Whether high text contrast is enabled.
/**
         * Called when the high text contrast enabled state changes.
         *
         * @param enabled Whether high text contrast is enabled.
         */
        void onHighTextContrastStateChanged(boolean enabled);
    }

    
Policy to inject behavior into the accessibility manager.

@hide
/**
     * Policy to inject behavior into the accessibility manager.
     *
     * @hide
     */
    public interface AccessibilityPolicy {
        
Checks whether accessibility is enabled.

Params:
  • accessibilityEnabled – Whether the accessibility layer is enabled.
Returns:whether accessibility is enabled.
/**
         * Checks whether accessibility is enabled.
         *
         * @param accessibilityEnabled Whether the accessibility layer is enabled.
         * @return whether accessibility is enabled.
         */
        boolean isEnabled(boolean accessibilityEnabled);

        
Notifies the policy for an accessibility event.

Params:
  • event – The event.
  • accessibilityEnabled – Whether the accessibility layer is enabled.
  • relevantEventTypes – The events relevant events.
Returns:The event to dispatch or null.
/**
         * Notifies the policy for an accessibility event.
         *
         * @param event The event.
         * @param accessibilityEnabled Whether the accessibility layer is enabled.
         * @param relevantEventTypes The events relevant events.
         * @return The event to dispatch or null.
         */
        @Nullable AccessibilityEvent onAccessibilityEvent(@NonNull AccessibilityEvent event,
                boolean accessibilityEnabled, @EventType int relevantEventTypes);

        
Gets the list of relevant events.

Params:
  • relevantEventTypes – The relevant events.
Returns:The relevant events to report.
/**
         * Gets the list of relevant events.
         *
         * @param relevantEventTypes The relevant events.
         * @return The relevant events to report.
         */
        @EventType int getRelevantEventTypes(@EventType int relevantEventTypes);

        
Gets the list of installed services to report.

Params:
  • installedService – The installed services.
Returns:The services to report.
/**
         * Gets the list of installed services to report.
         *
         * @param installedService The installed services.
         * @return The services to report.
         */
        @NonNull List<AccessibilityServiceInfo> getInstalledAccessibilityServiceList(
                @Nullable List<AccessibilityServiceInfo> installedService);

        
Gets the list of enabled accessibility services.

Params:
  • feedbackTypeFlags – The feedback type to query for.
  • enabledService – The enabled services.
Returns:The services to report.
/**
         * Gets the list of enabled accessibility services.
         *
         * @param feedbackTypeFlags The feedback type to query for.
         * @param enabledService The enabled services.
         * @return The services to report.
         */
        @Nullable List<AccessibilityServiceInfo> getEnabledAccessibilityServiceList(
                @FeedbackType int feedbackTypeFlags,
                @Nullable List<AccessibilityServiceInfo> enabledService);
    }

    private final IAccessibilityManagerClient.Stub mClient =
            new IAccessibilityManagerClient.Stub() {
        @Override
        public void setState(int state) {
            // We do not want to change this immediately as the application may
            // have already checked that accessibility is on and fired an event,
            // that is now propagating up the view tree, Hence, if accessibility
            // is now off an exception will be thrown. We want to have the exception
            // enforcement to guard against apps that fire unnecessary accessibility
            // events when accessibility is off.
            mHandler.obtainMessage(MyCallback.MSG_SET_STATE, state, 0).sendToTarget();
        }

        @Override
        public void notifyServicesStateChanged() {
            final ArrayMap<AccessibilityServicesStateChangeListener, Handler> listeners;
            synchronized (mLock) {
                if (mServicesStateChangeListeners.isEmpty()) {
                    return;
                }
                listeners = new ArrayMap<>(mServicesStateChangeListeners);
            }

            int numListeners = listeners.size();
            for (int i = 0; i < numListeners; i++) {
                final AccessibilityServicesStateChangeListener listener =
                        mServicesStateChangeListeners.keyAt(i);
                mServicesStateChangeListeners.valueAt(i).post(() -> listener
                        .onAccessibilityServicesStateChanged(AccessibilityManager.this));
            }
        }

        @Override
        public void setRelevantEventTypes(int eventTypes) {
            mRelevantEventTypes = eventTypes;
        }
    };

    
Get an AccessibilityManager instance (create one if necessary).

Params:
  • context – Context in which this manager operates.
@hide
/**
     * Get an AccessibilityManager instance (create one if necessary).
     *
     * @param context Context in which this manager operates.
     *
     * @hide
     */
    public static AccessibilityManager getInstance(Context context) {
        synchronized (sInstanceSync) {
            if (sInstance == null) {
                final int userId;
                if (Binder.getCallingUid() == Process.SYSTEM_UID
                        || context.checkCallingOrSelfPermission(
                                Manifest.permission.INTERACT_ACROSS_USERS)
                                        == PackageManager.PERMISSION_GRANTED
                        || context.checkCallingOrSelfPermission(
                                Manifest.permission.INTERACT_ACROSS_USERS_FULL)
                                        == PackageManager.PERMISSION_GRANTED) {
                    userId = UserHandle.USER_CURRENT;
                } else {
                    userId = context.getUserId();
                }
                sInstance = new AccessibilityManager(context, null, userId);
            }
        }
        return sInstance;
    }

    
Create an instance.

Params:
  • context – A Context.
  • service – An interface to the backing service.
  • userId – User id under which to run.
@hide
/**
     * Create an instance.
     *
     * @param context A {@link Context}.
     * @param service An interface to the backing service.
     * @param userId User id under which to run.
     *
     * @hide
     */
    public AccessibilityManager(Context context, IAccessibilityManager service, int userId) {
        // Constructor can't be chained because we can't create an instance of an inner class
        // before calling another constructor.
        mCallback = new MyCallback();
        mHandler = new Handler(context.getMainLooper(), mCallback);
        mUserId = userId;
        synchronized (mLock) {
            tryConnectToServiceLocked(service);
        }
    }

    
Create an instance.

Params:
  • handler – The handler to use
  • service – An interface to the backing service.
  • userId – User id under which to run.
@hide
/**
     * Create an instance.
     *
     * @param handler The handler to use
     * @param service An interface to the backing service.
     * @param userId User id under which to run.
     *
     * @hide
     */
    public AccessibilityManager(Handler handler, IAccessibilityManager service, int userId) {
        mCallback = new MyCallback();
        mHandler = handler;
        mUserId = userId;
        synchronized (mLock) {
            tryConnectToServiceLocked(service);
        }
    }

    
@hide
/**
     * @hide
     */
    public IAccessibilityManagerClient getClient() {
        return mClient;
    }

    
@hide
/**
     * @hide
     */
    @VisibleForTesting
    public Handler.Callback getCallback() {
        return mCallback;
    }

    
Returns if the accessibility in the system is enabled.

Returns:True if accessibility is enabled, false otherwise.
/**
     * Returns if the accessibility in the system is enabled.
     *
     * @return True if accessibility is enabled, false otherwise.
     */
    public boolean isEnabled() {
        synchronized (mLock) {
            return mIsEnabled || (mAccessibilityPolicy != null
                    && mAccessibilityPolicy.isEnabled(mIsEnabled));
        }
    }

    
Returns if the touch exploration in the system is enabled.

Returns:True if touch exploration is enabled, false otherwise.
/**
     * Returns if the touch exploration in the system is enabled.
     *
     * @return True if touch exploration is enabled, false otherwise.
     */
    public boolean isTouchExplorationEnabled() {
        synchronized (mLock) {
            IAccessibilityManager service = getServiceLocked();
            if (service == null) {
                return false;
            }
            return mIsTouchExplorationEnabled;
        }
    }

    
Returns if the high text contrast in the system is enabled.


Note: You need to query this only if you application is
doing its own rendering and does not rely on the platform rendering pipeline.



Returns:True if high text contrast is enabled, false otherwise.
@hide
/**
     * Returns if the high text contrast in the system is enabled.
     * <p>
     * <strong>Note:</strong> You need to query this only if you application is
     * doing its own rendering and does not rely on the platform rendering pipeline.
     * </p>
     *
     * @return True if high text contrast is enabled, false otherwise.
     *
     * @hide
     */
    public boolean isHighTextContrastEnabled() {
        synchronized (mLock) {
            IAccessibilityManager service = getServiceLocked();
            if (service == null) {
                return false;
            }
            return mIsHighTextContrastEnabled;
        }
    }

    
Params:
  • event – The event to send.
Throws:
/**
     * Sends an {@link AccessibilityEvent}.
     *
     * @param event The event to send.
     *
     * @throws IllegalStateException if accessibility is not enabled.
     *
     * <strong>Note:</strong> The preferred mechanism for sending custom accessibility
     * events is through calling
     * {@link android.view.ViewParent#requestSendAccessibilityEvent(View, AccessibilityEvent)}
     * instead of this method to allow predecessors to augment/filter events sent by
     * their descendants.
     */
    public void sendAccessibilityEvent(AccessibilityEvent event) {
        final IAccessibilityManager service;
        final int userId;
        final AccessibilityEvent dispatchedEvent;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
            event.setEventTime(SystemClock.uptimeMillis());
            if (mAccessibilityPolicy != null) {
                dispatchedEvent = mAccessibilityPolicy.onAccessibilityEvent(event,
                        mIsEnabled, mRelevantEventTypes);
                if (dispatchedEvent == null) {
                    return;
                }
            } else {
                dispatchedEvent = event;
            }
            if (!isEnabled()) {
                Looper myLooper = Looper.myLooper();
                if (myLooper == Looper.getMainLooper()) {
                    throw new IllegalStateException(
                            "Accessibility off. Did you forget to check that?");
                } else {
                    // If we're not running on the thread with the main looper, it's possible for
                    // the state of accessibility to change between checking isEnabled and
                    // calling this method. So just log the error rather than throwing the
                    // exception.
                    Log.e(LOG_TAG, "AccessibilityEvent sent with accessibility disabled");
                    return;
                }
            }
            if ((dispatchedEvent.getEventType() & mRelevantEventTypes) == 0) {
                if (DEBUG) {
                    Log.i(LOG_TAG, "Not dispatching irrelevant event: " + dispatchedEvent
                            + " that is not among "
                            + AccessibilityEvent.eventTypeToString(mRelevantEventTypes));
                }
                return;
            }
            userId = mUserId;
        }
        try {
            // it is possible that this manager is in the same process as the service but
            // client using it is called through Binder from another process. Example: MMS
            // app adds a SMS notification and the NotificationManagerService calls this method
            long identityToken = Binder.clearCallingIdentity();
            try {
                service.sendAccessibilityEvent(dispatchedEvent, userId);
            } finally {
                Binder.restoreCallingIdentity(identityToken);
            }
            if (DEBUG) {
                Log.i(LOG_TAG, dispatchedEvent + " sent");
            }
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error during sending " + dispatchedEvent + " ", re);
        } finally {
            if (event != dispatchedEvent) {
                event.recycle();
            }
            dispatchedEvent.recycle();
        }
    }

    
Requests feedback interruption from all accessibility services.

/**
     * Requests feedback interruption from all accessibility services.
     */
    public void interrupt() {
        final IAccessibilityManager service;
        final int userId;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
            if (!isEnabled()) {
                Looper myLooper = Looper.myLooper();
                if (myLooper == Looper.getMainLooper()) {
                    throw new IllegalStateException(
                            "Accessibility off. Did you forget to check that?");
                } else {
                    // If we're not running on the thread with the main looper, it's possible for
                    // the state of accessibility to change between checking isEnabled and
                    // calling this method. So just log the error rather than throwing the
                    // exception.
                    Log.e(LOG_TAG, "Interrupt called with accessibility disabled");
                    return;
                }
            }
            userId = mUserId;
        }
        try {
            service.interrupt(userId);
            if (DEBUG) {
                Log.i(LOG_TAG, "Requested interrupt from all services");
            }
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while requesting interrupt from all services. ", re);
        }
    }

    
Returns the ServiceInfos of the installed accessibility services. 
Returns:An unmodifiable list with ServiceInfos.
Deprecated:Use getInstalledAccessibilityServiceList()
/**
     * Returns the {@link ServiceInfo}s of the installed accessibility services.
     *
     * @return An unmodifiable list with {@link ServiceInfo}s.
     *
     * @deprecated Use {@link #getInstalledAccessibilityServiceList()}
     */
    @Deprecated
    public List<ServiceInfo> getAccessibilityServiceList() {
        List<AccessibilityServiceInfo> infos = getInstalledAccessibilityServiceList();
        List<ServiceInfo> services = new ArrayList<>();
        final int infoCount = infos.size();
        for (int i = 0; i < infoCount; i++) {
            AccessibilityServiceInfo info = infos.get(i);
            services.add(info.getResolveInfo().serviceInfo);
        }
        return Collections.unmodifiableList(services);
    }

    
Returns the AccessibilityServiceInfos of the installed accessibility services. 
Returns:An unmodifiable list with AccessibilityServiceInfos.
/**
     * Returns the {@link AccessibilityServiceInfo}s of the installed accessibility services.
     *
     * @return An unmodifiable list with {@link AccessibilityServiceInfo}s.
     */
    public List<AccessibilityServiceInfo> getInstalledAccessibilityServiceList() {
        final IAccessibilityManager service;
        final int userId;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return Collections.emptyList();
            }
            userId = mUserId;
        }

        List<AccessibilityServiceInfo> services = null;
        try {
            services = service.getInstalledAccessibilityServiceList(userId);
            if (DEBUG) {
                Log.i(LOG_TAG, "Installed AccessibilityServices " + services);
            }
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while obtaining the installed AccessibilityServices. ", re);
        }
        if (mAccessibilityPolicy != null) {
            services = mAccessibilityPolicy.getInstalledAccessibilityServiceList(services);
        }
        if (services != null) {
            return Collections.unmodifiableList(services);
        } else {
            return Collections.emptyList();
        }
    }

    
Returns the AccessibilityServiceInfos of the enabled accessibility services for a given feedback type. 
Params:
  • feedbackTypeFlags – The feedback type flags.
See Also:
Returns:An unmodifiable list with AccessibilityServiceInfos.
/**
     * Returns the {@link AccessibilityServiceInfo}s of the enabled accessibility services
     * for a given feedback type.
     *
     * @param feedbackTypeFlags The feedback type flags.
     * @return An unmodifiable list with {@link AccessibilityServiceInfo}s.
     *
     * @see AccessibilityServiceInfo#FEEDBACK_AUDIBLE
     * @see AccessibilityServiceInfo#FEEDBACK_GENERIC
     * @see AccessibilityServiceInfo#FEEDBACK_HAPTIC
     * @see AccessibilityServiceInfo#FEEDBACK_SPOKEN
     * @see AccessibilityServiceInfo#FEEDBACK_VISUAL
     * @see AccessibilityServiceInfo#FEEDBACK_BRAILLE
     */
    public List<AccessibilityServiceInfo> getEnabledAccessibilityServiceList(
            int feedbackTypeFlags) {
        final IAccessibilityManager service;
        final int userId;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return Collections.emptyList();
            }
            userId = mUserId;
        }

        List<AccessibilityServiceInfo> services = null;
        try {
            services = service.getEnabledAccessibilityServiceList(feedbackTypeFlags, userId);
            if (DEBUG) {
                Log.i(LOG_TAG, "Installed AccessibilityServices " + services);
            }
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while obtaining the installed AccessibilityServices. ", re);
        }
        if (mAccessibilityPolicy != null) {
            services = mAccessibilityPolicy.getEnabledAccessibilityServiceList(
                    feedbackTypeFlags, services);
        }
        if (services != null) {
            return Collections.unmodifiableList(services);
        } else {
            return Collections.emptyList();
        }
    }

    
Registers an AccessibilityStateChangeListener for changes in the global accessibility state of the system. Equivalent to calling addAccessibilityStateChangeListener(AccessibilityStateChangeListener, Handler) with a null handler. 
Params:
  • listener – The listener.
Returns:Always returns true.
/**
     * Registers an {@link AccessibilityStateChangeListener} for changes in
     * the global accessibility state of the system. Equivalent to calling
     * {@link #addAccessibilityStateChangeListener(AccessibilityStateChangeListener, Handler)}
     * with a null handler.
     *
     * @param listener The listener.
     * @return Always returns {@code true}.
     */
    public boolean addAccessibilityStateChangeListener(
            @NonNull AccessibilityStateChangeListener listener) {
        addAccessibilityStateChangeListener(listener, null);
        return true;
    }

    
Registers an AccessibilityStateChangeListener for changes in the global accessibility state of the system. If the listener has already been registered, the handler used to call it back is updated. 
Params:
  • listener – The listener.
  • handler – The handler on which the listener should be called back, or null for a callback on the process's main handler.
/**
     * Registers an {@link AccessibilityStateChangeListener} for changes in
     * the global accessibility state of the system. If the listener has already been registered,
     * the handler used to call it back is updated.
     *
     * @param listener The listener.
     * @param handler The handler on which the listener should be called back, or {@code null}
     *                for a callback on the process's main handler.
     */
    public void addAccessibilityStateChangeListener(
            @NonNull AccessibilityStateChangeListener listener, @Nullable Handler handler) {
        synchronized (mLock) {
            mAccessibilityStateChangeListeners
                    .put(listener, (handler == null) ? mHandler : handler);
        }
    }

    
Params:
  • listener – The listener.
Returns:True if the listener was previously registered.
/**
     * Unregisters an {@link AccessibilityStateChangeListener}.
     *
     * @param listener The listener.
     * @return True if the listener was previously registered.
     */
    public boolean removeAccessibilityStateChangeListener(
            @NonNull AccessibilityStateChangeListener listener) {
        synchronized (mLock) {
            int index = mAccessibilityStateChangeListeners.indexOfKey(listener);
            mAccessibilityStateChangeListeners.remove(listener);
            return (index >= 0);
        }
    }

    
Registers a TouchExplorationStateChangeListener for changes in the global touch exploration state of the system. Equivalent to calling addTouchExplorationStateChangeListener(TouchExplorationStateChangeListener, Handler) with a null handler. 
Params:
  • listener – The listener.
Returns:Always returns true.
/**
     * Registers a {@link TouchExplorationStateChangeListener} for changes in
     * the global touch exploration state of the system. Equivalent to calling
     * {@link #addTouchExplorationStateChangeListener(TouchExplorationStateChangeListener, Handler)}
     * with a null handler.
     *
     * @param listener The listener.
     * @return Always returns {@code true}.
     */
    public boolean addTouchExplorationStateChangeListener(
            @NonNull TouchExplorationStateChangeListener listener) {
        addTouchExplorationStateChangeListener(listener, null);
        return true;
    }

    
Registers an TouchExplorationStateChangeListener for changes in the global touch exploration state of the system. If the listener has already been registered, the handler used to call it back is updated. 
Params:
  • listener – The listener.
  • handler – The handler on which the listener should be called back, or null for a callback on the process's main handler.
/**
     * Registers an {@link TouchExplorationStateChangeListener} for changes in
     * the global touch exploration state of the system. If the listener has already been
     * registered, the handler used to call it back is updated.
     *
     * @param listener The listener.
     * @param handler The handler on which the listener should be called back, or {@code null}
     *                for a callback on the process's main handler.
     */
    public void addTouchExplorationStateChangeListener(
            @NonNull TouchExplorationStateChangeListener listener, @Nullable Handler handler) {
        synchronized (mLock) {
            mTouchExplorationStateChangeListeners
                    .put(listener, (handler == null) ? mHandler : handler);
        }
    }

    
Params:
  • listener – The listener.
Returns:True if listener was previously registered.
/**
     * Unregisters a {@link TouchExplorationStateChangeListener}.
     *
     * @param listener The listener.
     * @return True if listener was previously registered.
     */
    public boolean removeTouchExplorationStateChangeListener(
            @NonNull TouchExplorationStateChangeListener listener) {
        synchronized (mLock) {
            int index = mTouchExplorationStateChangeListeners.indexOfKey(listener);
            mTouchExplorationStateChangeListeners.remove(listener);
            return (index >= 0);
        }
    }

    
Params:
  • listener – The listener.
  • handler – The handler on which the listener should be called back, or null for a callback on the process's main handler.
@hide
/**
     * Registers a {@link AccessibilityServicesStateChangeListener}.
     *
     * @param listener The listener.
     * @param handler The handler on which the listener should be called back, or {@code null}
     *                for a callback on the process's main handler.
     * @hide
     */
    public void addAccessibilityServicesStateChangeListener(
            @NonNull AccessibilityServicesStateChangeListener listener, @Nullable Handler handler) {
        synchronized (mLock) {
            mServicesStateChangeListeners
                    .put(listener, (handler == null) ? mHandler : handler);
        }
    }

    
Params:
  • listener – The listener.
@hide
/**
     * Unregisters a {@link AccessibilityServicesStateChangeListener}.
     *
     * @param listener The listener.
     *
     * @hide
     */
    public void removeAccessibilityServicesStateChangeListener(
            @NonNull AccessibilityServicesStateChangeListener listener) {
        synchronized (mLock) {
            mServicesStateChangeListeners.remove(listener);
        }
    }

    /**
     * Registers a {@link AccessibilityRequestPreparer}.
     */
    public void addAccessibilityRequestPreparer(AccessibilityRequestPreparer preparer) {
        if (mRequestPreparerLists == null) {
            mRequestPreparerLists = new SparseArray<>(1);
        }
        int id = preparer.getView().getAccessibilityViewId();
        List<AccessibilityRequestPreparer> requestPreparerList = mRequestPreparerLists.get(id);
        if (requestPreparerList == null) {
            requestPreparerList = new ArrayList<>(1);
            mRequestPreparerLists.put(id, requestPreparerList);
        }
        requestPreparerList.add(preparer);
    }

    /**
     * Unregisters a {@link AccessibilityRequestPreparer}.
     */
    public void removeAccessibilityRequestPreparer(AccessibilityRequestPreparer preparer) {
        if (mRequestPreparerLists == null) {
            return;
        }
        int viewId = preparer.getView().getAccessibilityViewId();
        List<AccessibilityRequestPreparer> requestPreparerList = mRequestPreparerLists.get(viewId);
        if (requestPreparerList != null) {
            requestPreparerList.remove(preparer);
            if (requestPreparerList.isEmpty()) {
                mRequestPreparerLists.remove(viewId);
            }
        }
    }

    
Get the preparers that are registered for an accessibility ID

Params:
  • id – The ID of interest
Returns:The list of preparers, or null if there are none.
@hide
/**
     * Get the preparers that are registered for an accessibility ID
     *
     * @param id The ID of interest
     * @return The list of preparers, or {@code null} if there are none.
     *
     * @hide
     */
    public List<AccessibilityRequestPreparer> getRequestPreparersForAccessibilityId(int id) {
        if (mRequestPreparerLists == null) {
            return null;
        }
        return mRequestPreparerLists.get(id);
    }

    
Registers a HighTextContrastChangeListener for changes in the global high text contrast state of the system. 
Params:
  • listener – The listener.
@hide
/**
     * Registers a {@link HighTextContrastChangeListener} for changes in
     * the global high text contrast state of the system.
     *
     * @param listener The listener.
     *
     * @hide
     */
    public void addHighTextContrastStateChangeListener(
            @NonNull HighTextContrastChangeListener listener, @Nullable Handler handler) {
        synchronized (mLock) {
            mHighTextContrastStateChangeListeners
                    .put(listener, (handler == null) ? mHandler : handler);
        }
    }

    
Params:
  • listener – The listener.
@hide
/**
     * Unregisters a {@link HighTextContrastChangeListener}.
     *
     * @param listener The listener.
     *
     * @hide
     */
    public void removeHighTextContrastStateChangeListener(
            @NonNull HighTextContrastChangeListener listener) {
        synchronized (mLock) {
            mHighTextContrastStateChangeListeners.remove(listener);
        }
    }

    
Sets the AccessibilityPolicy controlling this manager. 
Params:
  • policy – The policy.
@hide
/**
     * Sets the {@link AccessibilityPolicy} controlling this manager.
     *
     * @param policy The policy.
     *
     * @hide
     */
    public void setAccessibilityPolicy(@Nullable AccessibilityPolicy policy) {
        synchronized (mLock) {
            mAccessibilityPolicy = policy;
        }
    }

    
Check if the accessibility volume stream is active.

Returns:True if accessibility volume is active (i.e. some service has requested it). False
otherwise.
@hide
/**
     * Check if the accessibility volume stream is active.
     *
     * @return True if accessibility volume is active (i.e. some service has requested it). False
     * otherwise.
     * @hide
     */
    public boolean isAccessibilityVolumeStreamActive() {
        List<AccessibilityServiceInfo> serviceInfos =
                getEnabledAccessibilityServiceList(AccessibilityServiceInfo.FEEDBACK_ALL_MASK);
        for (int i = 0; i < serviceInfos.size(); i++) {
            if ((serviceInfos.get(i).flags & FLAG_ENABLE_ACCESSIBILITY_VOLUME) != 0) {
                return true;
            }
        }
        return false;
    }

    
Report a fingerprint gesture to accessibility. Only available for the system process.

Params:
  • keyCode – The key code of the gesture
Returns:true if accessibility consumes the event. false if not.
@hide
/**
     * Report a fingerprint gesture to accessibility. Only available for the system process.
     *
     * @param keyCode The key code of the gesture
     * @return {@code true} if accessibility consumes the event. {@code false} if not.
     * @hide
     */
    public boolean sendFingerprintGesture(int keyCode) {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return false;
            }
        }
        try {
            return service.sendFingerprintGesture(keyCode);
        } catch (RemoteException e) {
            return false;
        }
    }

    
Sets the current state and notifies listeners, if necessary.

Params:
  • stateFlags – The state flags.
/**
     * Sets the current state and notifies listeners, if necessary.
     *
     * @param stateFlags The state flags.
     */
    private void setStateLocked(int stateFlags) {
        final boolean enabled = (stateFlags & STATE_FLAG_ACCESSIBILITY_ENABLED) != 0;
        final boolean touchExplorationEnabled =
                (stateFlags & STATE_FLAG_TOUCH_EXPLORATION_ENABLED) != 0;
        final boolean highTextContrastEnabled =
                (stateFlags & STATE_FLAG_HIGH_TEXT_CONTRAST_ENABLED) != 0;

        final boolean wasEnabled = isEnabled();
        final boolean wasTouchExplorationEnabled = mIsTouchExplorationEnabled;
        final boolean wasHighTextContrastEnabled = mIsHighTextContrastEnabled;

        // Ensure listeners get current state from isZzzEnabled() calls.
        mIsEnabled = enabled;
        mIsTouchExplorationEnabled = touchExplorationEnabled;
        mIsHighTextContrastEnabled = highTextContrastEnabled;

        if (wasEnabled != isEnabled()) {
            notifyAccessibilityStateChanged();
        }

        if (wasTouchExplorationEnabled != touchExplorationEnabled) {
            notifyTouchExplorationStateChanged();
        }

        if (wasHighTextContrastEnabled != highTextContrastEnabled) {
            notifyHighTextContrastStateChanged();
        }
    }

    
Find an installed service with the specified ComponentName. 
Params:
  • componentName – The name to match to the service.
Returns:The info corresponding to the installed service, or null if no such service is installed.
@hide
/**
     * Find an installed service with the specified {@link ComponentName}.
     *
     * @param componentName The name to match to the service.
     *
     * @return The info corresponding to the installed service, or {@code null} if no such service
     * is installed.
     * @hide
     */
    public AccessibilityServiceInfo getInstalledServiceInfoWithComponentName(
            ComponentName componentName) {
        final List<AccessibilityServiceInfo> installedServiceInfos =
                getInstalledAccessibilityServiceList();
        if ((installedServiceInfos == null) || (componentName == null)) {
            return null;
        }
        for (int i = 0; i < installedServiceInfos.size(); i++) {
            if (componentName.equals(installedServiceInfos.get(i).getComponentName())) {
                return installedServiceInfos.get(i);
            }
        }
        return null;
    }

    
Adds an accessibility interaction connection interface for a given window.

Params:
  • windowToken – The window token to which a connection is added.
  • connection – The connection.
@hide
/**
     * Adds an accessibility interaction connection interface for a given window.
     * @param windowToken The window token to which a connection is added.
     * @param connection The connection.
     *
     * @hide
     */
    public int addAccessibilityInteractionConnection(IWindow windowToken,
            String packageName, IAccessibilityInteractionConnection connection) {
        final IAccessibilityManager service;
        final int userId;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return View.NO_ID;
            }
            userId = mUserId;
        }
        try {
            return service.addAccessibilityInteractionConnection(windowToken, connection,
                    packageName, userId);
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while adding an accessibility interaction connection. ", re);
        }
        return View.NO_ID;
    }

    
Removed an accessibility interaction connection interface for a given window.

Params:
  • windowToken – The window token to which a connection is removed.
@hide
/**
     * Removed an accessibility interaction connection interface for a given window.
     * @param windowToken The window token to which a connection is removed.
     *
     * @hide
     */
    public void removeAccessibilityInteractionConnection(IWindow windowToken) {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
        }
        try {
            service.removeAccessibilityInteractionConnection(windowToken);
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while removing an accessibility interaction connection. ", re);
        }
    }

    
Perform the accessibility shortcut if the caller has permission.

@hide
/**
     * Perform the accessibility shortcut if the caller has permission.
     *
     * @hide
     */
    public void performAccessibilityShortcut() {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
        }
        try {
            service.performAccessibilityShortcut();
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error performing accessibility shortcut. ", re);
        }
    }

    
Notifies that the accessibility button in the system's navigation area has been clicked

@hide
/**
     * Notifies that the accessibility button in the system's navigation area has been clicked
     *
     * @hide
     */
    public void notifyAccessibilityButtonClicked() {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
        }
        try {
            service.notifyAccessibilityButtonClicked();
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while dispatching accessibility button click", re);
        }
    }

    
Notifies that the visibility of the accessibility button in the system's navigation area
has changed.

Params:
  • shown – true if the accessibility button is visible within the system navigation area, false otherwise
@hide
/**
     * Notifies that the visibility of the accessibility button in the system's navigation area
     * has changed.
     *
     * @param shown {@code true} if the accessibility button is visible within the system
     *                  navigation area, {@code false} otherwise
     * @hide
     */
    public void notifyAccessibilityButtonVisibilityChanged(boolean shown) {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
        }
        try {
            service.notifyAccessibilityButtonVisibilityChanged(shown);
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error while dispatching accessibility button visibility change", re);
        }
    }

    
Set an IAccessibilityInteractionConnection to replace the actions of a picture-in-picture
window. Intended for use by the System UI only.

Params:
  • connection – The connection to handle the actions. Set to null to avoid affecting the actions.
@hide
/**
     * Set an IAccessibilityInteractionConnection to replace the actions of a picture-in-picture
     * window. Intended for use by the System UI only.
     *
     * @param connection The connection to handle the actions. Set to {@code null} to avoid
     * affecting the actions.
     *
     * @hide
     */
    public void setPictureInPictureActionReplacingConnection(
            @Nullable IAccessibilityInteractionConnection connection) {
        final IAccessibilityManager service;
        synchronized (mLock) {
            service = getServiceLocked();
            if (service == null) {
                return;
            }
        }
        try {
            service.setPictureInPictureActionReplacingConnection(connection);
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "Error setting picture in picture action replacement", re);
        }
    }

    private IAccessibilityManager getServiceLocked() {
        if (mService == null) {
            tryConnectToServiceLocked(null);
        }
        return mService;
    }

    private void tryConnectToServiceLocked(IAccessibilityManager service) {
        if (service == null) {
            IBinder iBinder = ServiceManager.getService(Context.ACCESSIBILITY_SERVICE);
            if (iBinder == null) {
                return;
            }
            service = IAccessibilityManager.Stub.asInterface(iBinder);
        }

        try {
            final long userStateAndRelevantEvents = service.addClient(mClient, mUserId);
            setStateLocked(IntPair.first(userStateAndRelevantEvents));
            mRelevantEventTypes = IntPair.second(userStateAndRelevantEvents);
            mService = service;
        } catch (RemoteException re) {
            Log.e(LOG_TAG, "AccessibilityManagerService is dead", re);
        }
    }

    
Notifies the registered AccessibilityStateChangeListeners. 
/**
     * Notifies the registered {@link AccessibilityStateChangeListener}s.
     */
    private void notifyAccessibilityStateChanged() {
        final boolean isEnabled;
        final ArrayMap<AccessibilityStateChangeListener, Handler> listeners;
        synchronized (mLock) {
            if (mAccessibilityStateChangeListeners.isEmpty()) {
                return;
            }
            isEnabled = isEnabled();
            listeners = new ArrayMap<>(mAccessibilityStateChangeListeners);
        }

        final int numListeners = listeners.size();
        for (int i = 0; i < numListeners; i++) {
            final AccessibilityStateChangeListener listener = listeners.keyAt(i);
            listeners.valueAt(i).post(() ->
                    listener.onAccessibilityStateChanged(isEnabled));
        }
    }

    
Notifies the registered TouchExplorationStateChangeListeners. 
/**
     * Notifies the registered {@link TouchExplorationStateChangeListener}s.
     */
    private void notifyTouchExplorationStateChanged() {
        final boolean isTouchExplorationEnabled;
        final ArrayMap<TouchExplorationStateChangeListener, Handler> listeners;
        synchronized (mLock) {
            if (mTouchExplorationStateChangeListeners.isEmpty()) {
                return;
            }
            isTouchExplorationEnabled = mIsTouchExplorationEnabled;
            listeners = new ArrayMap<>(mTouchExplorationStateChangeListeners);
        }

        final int numListeners = listeners.size();
        for (int i = 0; i < numListeners; i++) {
            final TouchExplorationStateChangeListener listener = listeners.keyAt(i);
            listeners.valueAt(i).post(() ->
                    listener.onTouchExplorationStateChanged(isTouchExplorationEnabled));
        }
    }

    
Notifies the registered HighTextContrastChangeListeners. 
/**
     * Notifies the registered {@link HighTextContrastChangeListener}s.
     */
    private void notifyHighTextContrastStateChanged() {
        final boolean isHighTextContrastEnabled;
        final ArrayMap<HighTextContrastChangeListener, Handler> listeners;
        synchronized (mLock) {
            if (mHighTextContrastStateChangeListeners.isEmpty()) {
                return;
            }
            isHighTextContrastEnabled = mIsHighTextContrastEnabled;
            listeners = new ArrayMap<>(mHighTextContrastStateChangeListeners);
        }

        final int numListeners = listeners.size();
        for (int i = 0; i < numListeners; i++) {
            final HighTextContrastChangeListener listener = listeners.keyAt(i);
            listeners.valueAt(i).post(() ->
                    listener.onHighTextContrastStateChanged(isHighTextContrastEnabled));
        }
    }

    
Determines if the accessibility button within the system navigation area is supported.

Returns:true if the accessibility button is supported on this device, false otherwise
/**
     * Determines if the accessibility button within the system navigation area is supported.
     *
     * @return {@code true} if the accessibility button is supported on this device,
     * {@code false} otherwise
     */
    public static boolean isAccessibilityButtonSupported() {
        final Resources res = Resources.getSystem();
        return res.getBoolean(com.android.internal.R.bool.config_showNavigationBar);
    }

    private final class MyCallback implements Handler.Callback {
        public static final int MSG_SET_STATE = 1;

        @Override
        public boolean handleMessage(Message message) {
            switch (message.what) {
                case MSG_SET_STATE: {
                    // See comment at mClient
                    final int state = message.arg1;
                    synchronized (mLock) {
                        setStateLocked(state);
                    }
                } break;
            }
            return true;
        }
    }
}