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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.view.accessibility;
     18 
     19 import android.content.Context;
     20 import android.content.pm.ServiceInfo;
     21 
     22 import java.util.Collections;
     23 import java.util.List;
     24 
     25 /**
     26  * System level service that serves as an event dispatch for {@link AccessibilityEvent}s.
     27  * Such events are generated when something notable happens in the user interface,
     28  * for example an {@link android.app.Activity} starts, the focus or selection of a
     29  * {@link android.view.View} changes etc. Parties interested in handling accessibility
     30  * events implement and register an accessibility service which extends
     31  * {@link android.accessibilityservice.AccessibilityService}.
     32  *
     33  * @see AccessibilityEvent
     34  * @see android.accessibilityservice.AccessibilityService
     35  * @see android.content.Context#getSystemService
     36  */
     37 public final class AccessibilityManager {
     38     private static AccessibilityManager sInstance = new AccessibilityManager();
     39 
     40     /**
     41      * Get an AccessibilityManager instance (create one if necessary).
     42      *
     43      * @hide
     44      */
     45     public static AccessibilityManager getInstance(Context context) {
     46         return sInstance;
     47     }
     48 
     49     /**
     50      * Create an instance.
     51      *
     52      * @param context A {@link Context}.
     53      */
     54     private AccessibilityManager() {
     55     }
     56 
     57     /**
     58      * Returns if the {@link AccessibilityManager} is enabled.
     59      *
     60      * @return True if this {@link AccessibilityManager} is enabled, false otherwise.
     61      */
     62     public boolean isEnabled() {
     63         return false;
     64     }
     65 
     66     /**
     67      * Sends an {@link AccessibilityEvent}. If this {@link AccessibilityManager} is not
     68      * enabled the call is a NOOP.
     69      *
     70      * @param event The {@link AccessibilityEvent}.
     71      *
     72      * @throws IllegalStateException if a client tries to send an {@link AccessibilityEvent}
     73      *         while accessibility is not enabled.
     74      */
     75     public void sendAccessibilityEvent(AccessibilityEvent event) {
     76     }
     77 
     78     /**
     79      * Requests interruption of the accessibility feedback from all accessibility services.
     80      */
     81     public void interrupt() {
     82     }
     83 
     84     /**
     85      * Returns the {@link ServiceInfo}s of the installed accessibility services.
     86      *
     87      * @return An unmodifiable list with {@link ServiceInfo}s.
     88      */
     89     public List<ServiceInfo> getAccessibilityServiceList() {
     90         // normal implementation does this in some case, so let's do the same
     91         // (unmodifiableList wrapped around null).
     92         List<ServiceInfo> services = null;
     93         return Collections.unmodifiableList(services);
     94     }
     95 }
     96