| /* |
| * 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.os.Build; |
| import android.os.SystemProperties; |
| import android.util.Log; |
| import android.view.MotionEvent; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| |
| /** |
| * A classifier which calculates the variance of differences between successive angles in a stroke. |
| * For each stroke it keeps its last three points. If some successive points are the same, it |
| * ignores the repetitions. If a new point is added, the classifier calculates the angle between |
| * the last three points. After that, it calculates the difference between this angle and the |
| * previously calculated angle. Then it calculates the variance of the differences from a stroke. |
| * To the differences there is artificially added value 0.0 and the difference between the first |
| * angle and PI (angles are in radians). It helps with strokes which have few points and punishes |
| * more strokes which are not smooth. |
| * |
| * This classifier also tries to split the stroke into two parts in the place in which the biggest |
| * angle is. It calculates the angle variance of the two parts and sums them up. The reason the |
| * classifier is doing this, is because some human swipes at the beginning go for a moment in one |
| * direction and then they rapidly change direction for the rest of the stroke (like a tick). The |
| * final result is the minimum of angle variance of the whole stroke and the sum of angle variances |
| * of the two parts split up. The classifier tries the tick option only if the first part is |
| * shorter than the second part. |
| * |
| * Additionally, the classifier classifies the angles as left angles (those angles which value is |
| * in [0.0, PI - ANGLE_DEVIATION) interval), straight angles |
| * ([PI - ANGLE_DEVIATION, PI + ANGLE_DEVIATION] interval) and right angles |
| * ((PI + ANGLE_DEVIATION, 2 * PI) interval) and then calculates the percentage of angles which are |
| * in the same direction (straight angles can be left angels or right angles) |
| */ |
| public class AnglesClassifier extends StrokeClassifier { |
| private HashMap<Stroke, Data> mStrokeMap = new HashMap<>(); |
| |
| public static final boolean VERBOSE = SystemProperties.getBoolean("debug.falsing_log.ang", |
| Build.IS_DEBUGGABLE); |
| |
| private static String TAG = "ANG"; |
| |
| public AnglesClassifier(ClassifierData classifierData) { |
| mClassifierData = classifierData; |
| } |
| |
| @Override |
| public String getTag() { |
| return TAG; |
| } |
| |
| @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)); |
| |
| if (mStrokeMap.get(stroke) == null) { |
| mStrokeMap.put(stroke, new Data()); |
| } |
| mStrokeMap.get(stroke).addPoint(stroke.getPoints().get(stroke.getPoints().size() - 1)); |
| } |
| } |
| |
| @Override |
| public float getFalseTouchEvaluation(int type, Stroke stroke) { |
| Data data = mStrokeMap.get(stroke); |
| return AnglesVarianceEvaluator.evaluate(data.getAnglesVariance(), type) |
| + AnglesPercentageEvaluator.evaluate(data.getAnglesPercentage(), type); |
| } |
| |
| private static class Data { |
| private final float ANGLE_DEVIATION = (float) Math.PI / 20.0f; |
| |
| private List<Point> mLastThreePoints = new ArrayList<>(); |
| private float mFirstAngleVariance; |
| private float mPreviousAngle; |
| private float mBiggestAngle; |
| private float mSumSquares; |
| private float mSecondSumSquares; |
| private float mSum; |
| private float mSecondSum; |
| private float mCount; |
| private float mSecondCount; |
| private float mFirstLength; |
| private float mLength; |
| private float mAnglesCount; |
| private float mLeftAngles; |
| private float mRightAngles; |
| private float mStraightAngles; |
| |
| public Data() { |
| mFirstAngleVariance = 0.0f; |
| mPreviousAngle = (float) Math.PI; |
| mBiggestAngle = 0.0f; |
| mSumSquares = mSecondSumSquares = 0.0f; |
| mSum = mSecondSum = 0.0f; |
| mCount = mSecondCount = 1.0f; |
| mLength = mFirstLength = 0.0f; |
| mAnglesCount = mLeftAngles = mRightAngles = mStraightAngles = 0.0f; |
| } |
| |
| public void addPoint(Point point) { |
| // Checking if the added point is different than the previously added point |
| // Repetitions are being ignored so that proper angles are calculated. |
| if (mLastThreePoints.isEmpty() |
| || !mLastThreePoints.get(mLastThreePoints.size() - 1).equals(point)) { |
| if (!mLastThreePoints.isEmpty()) { |
| mLength += mLastThreePoints.get(mLastThreePoints.size() - 1).dist(point); |
| } |
| mLastThreePoints.add(point); |
| if (mLastThreePoints.size() == 4) { |
| mLastThreePoints.remove(0); |
| |
| float angle = mLastThreePoints.get(1).getAngle(mLastThreePoints.get(0), |
| mLastThreePoints.get(2)); |
| |
| mAnglesCount++; |
| if (angle < Math.PI - ANGLE_DEVIATION) { |
| mLeftAngles++; |
| } else if (angle <= Math.PI + ANGLE_DEVIATION) { |
| mStraightAngles++; |
| } else { |
| mRightAngles++; |
| } |
| |
| float difference = angle - mPreviousAngle; |
| |
| // If this is the biggest angle of the stroke so then we save the value of |
| // the angle variance so far and start to count the values for the angle |
| // variance of the second part. |
| if (mBiggestAngle < angle) { |
| mBiggestAngle = angle; |
| mFirstLength = mLength; |
| mFirstAngleVariance = getAnglesVariance(mSumSquares, mSum, mCount); |
| mSecondSumSquares = 0.0f; |
| mSecondSum = 0.0f; |
| mSecondCount = 1.0f; |
| } else { |
| mSecondSum += difference; |
| mSecondSumSquares += difference * difference; |
| mSecondCount += 1.0; |
| } |
| |
| mSum += difference; |
| mSumSquares += difference * difference; |
| mCount += 1.0; |
| mPreviousAngle = angle; |
| } |
| } |
| } |
| |
| public float getAnglesVariance(float sumSquares, float sum, float count) { |
| return sumSquares / count - (sum / count) * (sum / count); |
| } |
| |
| public float getAnglesVariance() { |
| float anglesVariance = getAnglesVariance(mSumSquares, mSum, mCount); |
| if (VERBOSE) { |
| FalsingLog.i(TAG, "getAnglesVariance: (first pass) " + anglesVariance); |
| FalsingLog.i(TAG, " - mFirstLength=" + mFirstLength); |
| FalsingLog.i(TAG, " - mLength=" + mLength); |
| } |
| if (mFirstLength < mLength / 2f) { |
| anglesVariance = Math.min(anglesVariance, mFirstAngleVariance |
| + getAnglesVariance(mSecondSumSquares, mSecondSum, mSecondCount)); |
| if (VERBOSE) FalsingLog.i(TAG, "getAnglesVariance: (second pass) " + anglesVariance); |
| } |
| return anglesVariance; |
| } |
| |
| public float getAnglesPercentage() { |
| if (mAnglesCount == 0.0f) { |
| if (VERBOSE) FalsingLog.i(TAG, "getAnglesPercentage: count==0, result=1"); |
| return 1.0f; |
| } |
| final float result = (Math.max(mLeftAngles, mRightAngles) + mStraightAngles) / mAnglesCount; |
| if (VERBOSE) { |
| FalsingLog.i(TAG, "getAnglesPercentage: left=" + mLeftAngles + " right=" |
| + mRightAngles + " straight=" + mStraightAngles + " count=" + mAnglesCount |
| + " result=" + result); |
| } |
| return result; |
| } |
| } |
| } |