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
17package com.android.incallui.answer.impl.classifier;
18
19import android.hardware.Sensor;
20import android.hardware.SensorEvent;
21import android.view.MotionEvent;
22import java.util.concurrent.TimeUnit;
23
24/**
25 * A classifier which looks at the proximity sensor during the gesture. It calculates the percentage
26 * the proximity sensor showing the near state during the whole gesture
27 */
28class ProximityClassifier extends GestureClassifier {
29  private long gestureStartTimeNano;
30  private long nearStartTimeNano;
31  private long nearDuration;
32  private boolean near;
33  private float averageNear;
34
35  public ProximityClassifier(ClassifierData classifierData) {}
36
37  @Override
38  public String getTag() {
39    return "PROX";
40  }
41
42  @Override
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      gestureStartTimeNano = TimeUnit.MILLISECONDS.toNanos(event.getEventTime());
55      nearStartTimeNano = TimeUnit.MILLISECONDS.toNanos(event.getEventTime());
56      nearDuration = 0;
57    }
58
59    if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
60      update(near, TimeUnit.MILLISECONDS.toNanos(event.getEventTime()));
61      long duration = TimeUnit.MILLISECONDS.toNanos(event.getEventTime()) - gestureStartTimeNano;
62
63      if (duration == 0) {
64        averageNear = near ? 1.0f : 0.0f;
65      } else {
66        averageNear = (float) nearDuration / (float) duration;
67      }
68    }
69  }
70
71  /**
72   * @param near is the sensor showing the near state right now
73   * @param timestampNano time of this event in nanoseconds
74   */
75  private void update(boolean near, long timestampNano) {
76    // This if is necessary because MotionEvents and SensorEvents do not come in
77    // chronological order
78    if (timestampNano > nearStartTimeNano) {
79      // if the state before was near then add the difference of the current time and
80      // mNearStartTimeNano to mNearDuration.
81      if (this.near) {
82        nearDuration += timestampNano - nearStartTimeNano;
83      }
84
85      // if the new state is near, set mNearStartTimeNano equal to this moment.
86      if (near) {
87        nearStartTimeNano = timestampNano;
88      }
89    }
90    this.near = near;
91  }
92
93  @Override
94  public float getFalseTouchEvaluation() {
95    return ProximityEvaluator.evaluate(averageNear);
96  }
97}
98