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/*
* Copyright (C) 2020 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 static com.android.systemui.classifier.FalsingModule.DOUBLE_TAP_TIMEOUT_MS;
import static com.android.systemui.classifier.FalsingModule.DOUBLE_TAP_TOUCH_SLOP;
import android.view.MotionEvent;
import java.util.List;
import javax.inject.Inject;
import javax.inject.Named;
/**
* Returns a false touch if the most two recent gestures are not taps or are too far apart.
*/
public class DoubleTapClassifier extends FalsingClassifier {
private final SingleTapClassifier mSingleTapClassifier;
private final float mDoubleTapSlop;
private final long mDoubleTapTimeMs;
@Inject
DoubleTapClassifier(FalsingDataProvider dataProvider, SingleTapClassifier singleTapClassifier,
@Named(DOUBLE_TAP_TOUCH_SLOP) float doubleTapSlop,
@Named(DOUBLE_TAP_TIMEOUT_MS) long doubleTapTimeMs) {
super(dataProvider);
mSingleTapClassifier = singleTapClassifier;
mDoubleTapSlop = doubleTapSlop;
mDoubleTapTimeMs = doubleTapTimeMs;
}
@Override
Result calculateFalsingResult(
@Classifier.InteractionType int interactionType,
double historyBelief, double historyConfidence) {
List<MotionEvent> secondTapEvents = getRecentMotionEvents();
List<MotionEvent> firstTapEvents = getPriorMotionEvents();
StringBuilder reason = new StringBuilder();
if (firstTapEvents == null) {
return falsed(0, "Only one gesture recorded");
}
return !isDoubleTap(firstTapEvents, secondTapEvents, reason)
? falsed(0.5, reason.toString()) : Result.passed(0.5);
}
/** Returns true if the two supplied lists of {@link MotionEvent}s look like a double-tap. */
public boolean isDoubleTap(List<MotionEvent> firstEvents, List<MotionEvent> secondEvents,
StringBuilder reason) {
Result firstTap = mSingleTapClassifier.isTap(firstEvents, 0.5);
if (firstTap.isFalse()) {
reason.append("First gesture is not a tap. ").append(firstTap.getReason());
return false;
}
Result secondTap = mSingleTapClassifier.isTap(secondEvents, 0.5);
if (secondTap.isFalse()) {
reason.append("Second gesture is not a tap. ").append(secondTap.getReason());
return false;
}
MotionEvent firstFinalEvent = firstEvents.get(firstEvents.size() - 1);
MotionEvent secondFinalEvent = secondEvents.get(secondEvents.size() - 1);
long dt = secondFinalEvent.getEventTime() - firstFinalEvent.getEventTime();
if (dt > mDoubleTapTimeMs) {
reason.append("Time between taps too large: ").append(dt).append("ms");
return false;
}
if (Math.abs(firstFinalEvent.getX() - secondFinalEvent.getX()) >= mDoubleTapSlop) {
reason.append("Delta X between taps too large:")
.append(Math.abs(firstFinalEvent.getX() - secondFinalEvent.getX()))
.append(" vs ")
.append(mDoubleTapSlop);
return false;
}
if (Math.abs(firstFinalEvent.getY() - secondFinalEvent.getY()) >= mDoubleTapSlop) {
reason.append("Delta Y between taps too large:")
.append(Math.abs(firstFinalEvent.getY() - secondFinalEvent.getY()))
.append(" vs ")
.append(mDoubleTapSlop);
return false;
}
return true;
}
}
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