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diff --git a/java/com/android/incallui/answer/impl/classifier/AnglesClassifier.java b/java/com/android/incallui/answer/impl/classifier/AnglesClassifier.java
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+/*
+ * Copyright (C) 2016 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.incallui.answer.impl.classifier;
+
+import android.util.ArrayMap;
+import android.view.MotionEvent;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 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.
+ *
+ * <p>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.
+ *
+ * <p>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)
+ */
+class AnglesClassifier extends StrokeClassifier {
+  private Map<Stroke, Data> mStrokeMap = new ArrayMap<>();
+
+  public AnglesClassifier(ClassifierData classifierData) {
+    mClassifierData = classifierData;
+  }
+
+  @Override
+  public String getTag() {
+    return "ANG";
+  }
+
+  @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(Stroke stroke) {
+    Data data = mStrokeMap.get(stroke);
+    return AnglesVarianceEvaluator.evaluate(data.getAnglesVariance())
+        + AnglesPercentageEvaluator.evaluate(data.getAnglesPercentage());
+  }
+
+  private static class Data {
+    private static final float ANGLE_DEVIATION = (float) Math.PI / 20.0f;
+    private static final float MIN_MOVE_DIST_DP = .01f;
+
+    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 and short distances are being ignored so that proper angles are calculated.
+      if (mLastThreePoints.isEmpty()
+          || (!mLastThreePoints.get(mLastThreePoints.size() - 1).equals(point)
+              && (mLastThreePoints.get(mLastThreePoints.size() - 1).dist(point)
+                  > MIN_MOVE_DIST_DP))) {
+        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 += 1.0f;
+          }
+
+          mSum += difference;
+          mSumSquares += difference * difference;
+          mCount += 1.0f;
+          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 (mFirstLength < mLength / 2f) {
+        anglesVariance =
+            Math.min(
+                anglesVariance,
+                mFirstAngleVariance
+                    + getAnglesVariance(mSecondSumSquares, mSecondSum, mSecondCount));
+      }
+      return anglesVariance;
+    }
+
+    public float getAnglesPercentage() {
+      if (mAnglesCount == 0.0f) {
+        return 1.0f;
+      }
+      return (Math.max(mLeftAngles, mRightAngles) + mStraightAngles) / mAnglesCount;
+    }
+  }
+}