Blazej Magnowski | 68d0c9b | 2015-09-18 17:25:55 -0700 | [diff] [blame] | 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.view.MotionEvent; |
| 20 | |
| 21 | import java.util.HashMap; |
| 22 | |
| 23 | /** |
| 24 | * A classifier which looks at the speed and distance between successive points of a Stroke. |
| 25 | * It looks at two consecutive speeds between two points and calculates the ratio between them. |
| 26 | * The final result is the maximum of these values. It does the same for distances. If some speed |
| 27 | * or distance is equal to zero then the ratio between this and the next part is not calculated. To |
| 28 | * the duration of each part there is added one nanosecond so that it is always possible to |
| 29 | * calculate the speed of a part. |
| 30 | */ |
| 31 | public class AccelerationClassifier extends StrokeClassifier { |
| 32 | private final HashMap<Stroke, Data> mStrokeMap = new HashMap<>(); |
| 33 | |
| 34 | public AccelerationClassifier(ClassifierData classifierData) { |
| 35 | mClassifierData = classifierData; |
| 36 | } |
| 37 | |
| 38 | @Override |
| 39 | public void onTouchEvent(MotionEvent event) { |
| 40 | int action = event.getActionMasked(); |
| 41 | |
| 42 | if (action == MotionEvent.ACTION_DOWN) { |
| 43 | mStrokeMap.clear(); |
| 44 | } |
| 45 | |
| 46 | for (int i = 0; i < event.getPointerCount(); i++) { |
| 47 | Stroke stroke = mClassifierData.getStroke(event.getPointerId(i)); |
| 48 | Point point = stroke.getPoints().get(stroke.getPoints().size() - 1); |
| 49 | if (mStrokeMap.get(stroke) == null) { |
| 50 | mStrokeMap.put(stroke, new Data(point)); |
| 51 | } else { |
| 52 | mStrokeMap.get(stroke).addPoint(point); |
| 53 | } |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | @Override |
| 58 | public float getFalseTouchEvaluation(int type, Stroke stroke) { |
| 59 | Data data = mStrokeMap.get(stroke); |
| 60 | return SpeedRatioEvaluator.evaluate(data.maxSpeedRatio) |
| 61 | + DistanceRatioEvaluator.evaluate(data.maxDistanceRatio); |
| 62 | } |
| 63 | |
| 64 | private static class Data { |
| 65 | public Point previousPoint; |
| 66 | public float previousSpeed; |
| 67 | public float previousDistance; |
| 68 | public float maxSpeedRatio; |
| 69 | public float maxDistanceRatio; |
| 70 | |
| 71 | public Data(Point point) { |
| 72 | previousPoint = point; |
| 73 | previousSpeed = previousDistance = 0.0f; |
| 74 | maxDistanceRatio = maxSpeedRatio = 0.0f; |
| 75 | } |
| 76 | |
| 77 | public void addPoint(Point point) { |
| 78 | float distance = previousPoint.dist(point); |
| 79 | float duration = (float) (point.timeOffsetNano - previousPoint.timeOffsetNano + 1); |
| 80 | float speed = distance / duration; |
| 81 | if (previousDistance != 0.0f) { |
| 82 | maxDistanceRatio = Math.max(maxDistanceRatio, distance / previousDistance); |
| 83 | } |
| 84 | |
| 85 | if (previousSpeed != 0.0f) { |
| 86 | maxSpeedRatio = Math.max(maxSpeedRatio, speed / previousSpeed); |
| 87 | } |
| 88 | |
| 89 | previousDistance = distance; |
| 90 | previousSpeed = speed; |
| 91 | previousPoint = point; |
| 92 | } |
| 93 | } |
| 94 | } |