| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License |
| */ |
| |
| package com.android.systemui.classifier; |
| |
| import android.view.MotionEvent; |
| |
| import java.util.HashMap; |
| |
| /** |
| * A classifier which looks at the speed and distance between successive points of a Stroke. |
| * It looks at two consecutive speeds between two points and calculates the ratio between them. |
| * The final result is the maximum of these values. It does the same for distances. If some speed |
| * or distance is equal to zero then the ratio between this and the next part is not calculated. To |
| * the duration of each part there is added one nanosecond so that it is always possible to |
| * calculate the speed of a part. |
| */ |
| public class AccelerationClassifier extends StrokeClassifier { |
| private final HashMap<Stroke, Data> mStrokeMap = new HashMap<>(); |
| |
| public AccelerationClassifier(ClassifierData classifierData) { |
| mClassifierData = classifierData; |
| } |
| |
| @Override |
| public String getTag() { |
| return "ACC"; |
| } |
| |
| @Override |
| public void onTouchEvent(MotionEvent event) { |
| int action = event.getActionMasked(); |
| |
| if (action == MotionEvent.ACTION_DOWN) { |
| mStrokeMap.clear(); |
| } |
| |
| for (int i = 0; i < event.getPointerCount(); i++) { |
| Stroke stroke = mClassifierData.getStroke(event.getPointerId(i)); |
| Point point = stroke.getPoints().get(stroke.getPoints().size() - 1); |
| if (mStrokeMap.get(stroke) == null) { |
| mStrokeMap.put(stroke, new Data(point)); |
| } else { |
| mStrokeMap.get(stroke).addPoint(point); |
| } |
| } |
| } |
| |
| @Override |
| public float getFalseTouchEvaluation(int type, Stroke stroke) { |
| Data data = mStrokeMap.get(stroke); |
| return 2 * SpeedRatioEvaluator.evaluate(data.maxSpeedRatio); |
| } |
| |
| private static class Data { |
| |
| static final float MILLIS_TO_NANOS = 1e6f; |
| |
| Point previousPoint; |
| float previousSpeed = 0; |
| float maxSpeedRatio = 0; |
| |
| public Data(Point point) { |
| previousPoint = point; |
| } |
| |
| public void addPoint(Point point) { |
| float distance = previousPoint.dist(point); |
| float duration = (float) (point.timeOffsetNano - previousPoint.timeOffsetNano + 1); |
| float speed = distance / duration; |
| |
| if (duration > 20 * MILLIS_TO_NANOS || duration < 5 * MILLIS_TO_NANOS) { |
| // reject this segment and ensure we won't use data about it in the next round. |
| previousSpeed = 0; |
| previousPoint = point; |
| return; |
| } |
| if (previousSpeed != 0.0f) { |
| maxSpeedRatio = Math.max(maxSpeedRatio, speed / previousSpeed); |
| } |
| |
| previousSpeed = speed; |
| previousPoint = point; |
| } |
| } |
| } |