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      1 /*
      2  * Copyright (C) 2011 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 com.android.server.accessibility;
     18 
     19 import com.android.server.wm.InputFilter;
     20 
     21 import android.content.Context;
     22 import android.util.Slog;
     23 import android.view.InputDevice;
     24 import android.view.InputEvent;
     25 import android.view.MotionEvent;
     26 import android.view.WindowManagerPolicy;
     27 
     28 /**
     29  * Input filter for accessibility.
     30  *
     31  * Currently just a stub but will eventually implement touch exploration, etc.
     32  */
     33 public class AccessibilityInputFilter extends InputFilter {
     34     private static final String TAG = "AccessibilityInputFilter";
     35     private static final boolean DEBUG = false;
     36 
     37     private final Context mContext;
     38 
     39     /**
     40      * This is an interface for explorers that take a {@link MotionEvent}
     41      * stream and perform touch exploration of the screen content.
     42      */
     43     public interface Explorer {
     44         /**
     45          * Handles a {@link MotionEvent}.
     46          *
     47          * @param event The event to handle.
     48          * @param policyFlags The policy flags associated with the event.
     49          */
     50         public void onMotionEvent(MotionEvent event, int policyFlags);
     51 
     52         /**
     53          * Requests that the explorer clears its internal state.
     54          *
     55          * @param event The last received event.
     56          * @param policyFlags The policy flags associated with the event.
     57          */
     58         public void clear(MotionEvent event, int policyFlags);
     59 
     60         /**
     61          * Requests that the explorer clears its internal state.
     62          */
     63         public void clear();
     64     }
     65 
     66     private TouchExplorer mTouchExplorer;
     67     private int mTouchscreenSourceDeviceId;
     68 
     69     public AccessibilityInputFilter(Context context) {
     70         super(context.getMainLooper());
     71         mContext = context;
     72     }
     73 
     74     @Override
     75     public void onInstalled() {
     76         if (DEBUG) {
     77             Slog.d(TAG, "Accessibility input filter installed.");
     78         }
     79         mTouchExplorer = new TouchExplorer(this, mContext);
     80         super.onInstalled();
     81     }
     82 
     83     @Override
     84     public void onUninstalled() {
     85         if (DEBUG) {
     86             Slog.d(TAG, "Accessibility input filter uninstalled.");
     87         }
     88         mTouchExplorer.clear();
     89         super.onUninstalled();
     90     }
     91 
     92     @Override
     93     public void onInputEvent(InputEvent event, int policyFlags) {
     94         if (DEBUG) {
     95             Slog.d(TAG, "Received event: " + event + ", policyFlags=0x"
     96                     + Integer.toHexString(policyFlags));
     97         }
     98         if (event.getSource() == InputDevice.SOURCE_TOUCHSCREEN) {
     99             MotionEvent motionEvent = (MotionEvent) event;
    100             int deviceId = event.getDeviceId();
    101             if (mTouchscreenSourceDeviceId != deviceId) {
    102                 mTouchscreenSourceDeviceId = deviceId;
    103                 mTouchExplorer.clear(motionEvent, policyFlags);
    104             }
    105             if ((policyFlags & WindowManagerPolicy.FLAG_PASS_TO_USER) != 0) {
    106                 mTouchExplorer.onMotionEvent(motionEvent, policyFlags);
    107             } else {
    108                 mTouchExplorer.clear(motionEvent, policyFlags);
    109             }
    110         } else {
    111             super.onInputEvent(event, policyFlags);
    112         }
    113     }
    114 }
    115