Improved angles variance and added the angles percentage evaluation
Change-Id: I312529ea89707d27a7ef1a5ffd6d94427eaf6e8f
diff --git a/packages/SystemUI/src/com/android/systemui/classifier/SpeedAnglesClassifier.java b/packages/SystemUI/src/com/android/systemui/classifier/SpeedAnglesClassifier.java
new file mode 100644
index 0000000..d544a3d
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/classifier/SpeedAnglesClassifier.java
@@ -0,0 +1,145 @@
+/*
+ * 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.lang.Math;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+/**
+ * A classifier which for each point from a stroke, it creates a point on plane with coordinates
+ * (timeOffsetNano, distanceCoveredUpToThisPoint) (scaled by DURATION_SCALE and LENGTH_SCALE)
+ * and then it calculates the angle variance of these points like the class
+ * {@link AnglesClassifier} (without splitting it into two parts). The classifier ignores
+ * the last point of a stroke because the UP event comes in with some delay and this ruins the
+ * smoothness of this curve. Additionally, the classifier classifies calculates the percentage of
+ * angles which value is in [PI - ANGLE_DEVIATION, 2* PI) interval. The reason why the classifier
+ * does that is because the speed of a good stroke is most often increases, so most of these angels
+ * should be in this interval.
+ */
+public class SpeedAnglesClassifier extends StrokeClassifier {
+ private HashMap<Stroke, Data> mStrokeMap = new HashMap<>();
+
+ public SpeedAnglesClassifier(ClassifierData classifierData) {
+ mClassifierData = classifierData;
+ }
+
+ @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());
+ }
+
+ if (action != MotionEvent.ACTION_UP && action != MotionEvent.ACTION_CANCEL
+ && !(action == MotionEvent.ACTION_POINTER_UP && i == event.getActionIndex())) {
+ 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 SpeedVarianceEvaluator.evaluate(data.getAnglesVariance())
+ + SpeedAnglesPercentageEvaluator.evaluate(data.getAnglesPercentage());
+ }
+
+ private static class Data {
+ private final float DURATION_SCALE = 1e8f;
+ private final float LENGTH_SCALE = 1.0f;
+ private final float ANGLE_DEVIATION = (float) Math.PI / 10.0f;
+
+ private List<Point> mLastThreePoints = new ArrayList<>();
+ private Point mPreviousPoint;
+ private float mPreviousAngle;
+ private float mSumSquares;
+ private float mSum;
+ private float mCount;
+ private float mDist;
+ private float mAnglesCount;
+ private float mAcceleratingAngles;
+
+ public Data() {
+ mPreviousPoint = null;
+ mPreviousAngle = (float) Math.PI;
+ mSumSquares = 0.0f;
+ mSum = 0.0f;
+ mCount = 1.0f;
+ mDist = 0.0f;
+ mAnglesCount = mAcceleratingAngles = 0.0f;
+ }
+
+ public void addPoint(Point point) {
+ if (mPreviousPoint != null) {
+ mDist += mPreviousPoint.dist(point);
+ }
+
+ mPreviousPoint = point;
+ Point speedPoint = new Point((float) point.timeOffsetNano / DURATION_SCALE,
+ mDist / LENGTH_SCALE);
+
+ // 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(speedPoint)) {
+ mLastThreePoints.add(speedPoint);
+ if (mLastThreePoints.size() == 4) {
+ mLastThreePoints.remove(0);
+
+ float angle = mLastThreePoints.get(1).getAngle(mLastThreePoints.get(0),
+ mLastThreePoints.get(2));
+
+ mAnglesCount++;
+ if (angle >= (float) Math.PI - ANGLE_DEVIATION) {
+ mAcceleratingAngles++;
+ }
+
+ float difference = angle - mPreviousAngle;
+ mSum += difference;
+ mSumSquares += difference * difference;
+ mCount += 1.0;
+ mPreviousAngle = angle;
+ }
+ }
+ }
+
+ public float getAnglesVariance() {
+ return mSumSquares / mCount - (mSum / mCount) * (mSum / mCount);
+ }
+
+ public float getAnglesPercentage() {
+ if (mAnglesCount == 0.0f) {
+ return 1.0f;
+ }
+ return (mAcceleratingAngles) / mAnglesCount;
+ }
+ }
+}
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