1 /*
2  * Copyright (C) 2015 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.systemui.classifier;
18 
19 import android.hardware.Sensor;
20 import android.hardware.SensorEvent;
21 import android.view.MotionEvent;
22 
23 /**
24  * A classifier which looks at the proximity sensor during the gesture. It calculates the percentage
25  * the proximity sensor showing the near state during the whole gesture
26  */
27 public class ProximityClassifier extends GestureClassifier {
28     private long mGestureStartTimeNano;
29     private long mNearStartTimeNano;
30     private long mNearDuration;
31     private boolean mNear;
32     private float mAverageNear;
33 
ProximityClassifier(ClassifierData classifierData)34     public ProximityClassifier(ClassifierData classifierData) {
35     }
36 
37     @Override
getTag()38     public String getTag() {
39         return "PROX";
40     }
41 
42     @Override
onSensorChanged(SensorEvent event)43     public void onSensorChanged(SensorEvent event) {
44         if (event.sensor.getType() == Sensor.TYPE_PROXIMITY) {
45             update(event.values[0] < event.sensor.getMaximumRange(), event.timestamp);
46         }
47     }
48 
49     @Override
50     public void onTouchEvent(MotionEvent event) {
51         int action = event.getActionMasked();
52 
53         if (action == MotionEvent.ACTION_DOWN) {
54             mGestureStartTimeNano = event.getEventTimeNano();
55             mNearStartTimeNano = event.getEventTimeNano();
56             mNearDuration = 0;
57         }
58 
59         if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
60             update(mNear, event.getEventTimeNano());
61             long duration = event.getEventTimeNano() - mGestureStartTimeNano;
62 
63             if (duration == 0) {
64                 mAverageNear = mNear ? 1.0f : 0.0f;
65             } else {
66                 mAverageNear = (float) mNearDuration / (float) duration;
67             }
68         }
69     }
70 
71 
72     /**
73      * @param near is the sensor showing the near state right now
74      * @param timestampNano time of this event in nanoseconds
75      */
76     private void update(boolean near, long timestampNano) {
77         // This if is necessary because MotionEvents and SensorEvents do not come in
78         // chronological order
79         if (timestampNano > mNearStartTimeNano) {
80             // if the state before was near then add the difference of the current time and
81             // mNearStartTimeNano to mNearDuration.
82             if (mNear) {
83                 mNearDuration += timestampNano - mNearStartTimeNano;
84             }
85 
86             // if the new state is near, set mNearStartTimeNano equal to this moment.
87             if (near) {
88                 mNearStartTimeNano = timestampNano;
89             }
90         }
91         mNear = near;
92     }
93 
94     @Override
getFalseTouchEvaluation(int type)95     public float getFalseTouchEvaluation(int type) {
96         return ProximityEvaluator.evaluate(mAverageNear, type);
97     }
98 }
99