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/*
* Copyright (C) 2016 Google Inc.
*
* 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.setupwizardlib.gesture;
import android.graphics.Rect;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
/**
* Helper class to detect the consective-tap gestures on a view.
*
* <p>This class is instantiated and used similar to a GestureDetector, where onTouchEvent should be
* called when there are MotionEvents this detector should know about.
*/
public final class ConsecutiveTapsGestureDetector {
public interface OnConsecutiveTapsListener {
/** Callback method when the user tapped on the target view X number of times. */
void onConsecutiveTaps(int numOfConsecutiveTaps);
}
private final View view;
private final OnConsecutiveTapsListener listener;
private final int consecutiveTapTouchSlopSquare;
private final int consecutiveTapTimeout;
private int consecutiveTapsCounter = 0;
private MotionEvent previousTapEvent;
/**
* @param listener The listener that responds to the gesture.
* @param view The target view that associated with consecutive-tap gesture.
*/
public ConsecutiveTapsGestureDetector(OnConsecutiveTapsListener listener, View view) {
this.listener = listener;
this.view = view;
int doubleTapSlop = ViewConfiguration.get(this.view.getContext()).getScaledDoubleTapSlop();
consecutiveTapTouchSlopSquare = doubleTapSlop * doubleTapSlop;
consecutiveTapTimeout = ViewConfiguration.getDoubleTapTimeout();
}
/**
* This method should be called from the relevant activity or view, typically in onTouchEvent,
* onInterceptTouchEvent or dispatchTouchEvent.
*
* @param ev The motion event
*/
public void onTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_UP) {
Rect viewRect = new Rect();
int[] leftTop = new int[2];
view.getLocationOnScreen(leftTop);
viewRect.set(
leftTop[0], leftTop[1], leftTop[0] + view.getWidth(), leftTop[1] + view.getHeight());
if (viewRect.contains((int) ev.getX(), (int) ev.getY())) {
if (isConsecutiveTap(ev)) {
consecutiveTapsCounter++;
} else {
consecutiveTapsCounter = 1;
}
listener.onConsecutiveTaps(consecutiveTapsCounter);
} else {
// Touch outside the target view. Reset counter.
consecutiveTapsCounter = 0;
}
if (previousTapEvent != null) {
previousTapEvent.recycle();
}
previousTapEvent = MotionEvent.obtain(ev);
}
}
/** Resets the consecutive-tap counter to zero. */
public void resetCounter() {
consecutiveTapsCounter = 0;
}
/**
* Returns true if the distance between consecutive tap is within {@link
* #consecutiveTapTouchSlopSquare}. False, otherwise.
*/
private boolean isConsecutiveTap(MotionEvent currentTapEvent) {
if (previousTapEvent == null) {
return false;
}
double deltaX = previousTapEvent.getX() - currentTapEvent.getX();
double deltaY = previousTapEvent.getY() - currentTapEvent.getY();
long deltaTime = currentTapEvent.getEventTime() - previousTapEvent.getEventTime();
return (deltaX * deltaX + deltaY * deltaY <= consecutiveTapTouchSlopSquare)
&& deltaTime < consecutiveTapTimeout;
}
}
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