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/*
* Copyright 2017 Google Inc. All Rights Reserved.
* 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.google.skar.examples.helloskar.helpers;
import android.content.Context;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
/**
* Helper to detect taps using Android GestureDetector, and pass the taps between UI thread and
* render thread.
*/
public final class TapHelper implements OnTouchListener {
private final GestureDetector gestureDetector;
private final BlockingQueue<MotionEvent> queuedSingleTaps = new ArrayBlockingQueue<>(16);
private final BlockingQueue<ScrollEvent> queuedFingerHold = new ArrayBlockingQueue<>(16);
private boolean isScrolling = false;
private boolean previousScroll = true;
public static class ScrollEvent {
public MotionEvent e;
public boolean isStartOfScroll;
public ScrollEvent(MotionEvent e, boolean isStartOfScroll) {
this.e = e;
this.isStartOfScroll = isStartOfScroll;
}
}
/**
* Creates the tap helper.
*
* @param context the application's context.
*/
public TapHelper(Context context) {
gestureDetector =
new GestureDetector(
context,
new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onSingleTapUp(MotionEvent e) {
// Queue tap if there is space. Tap is lost if queue is full.
queuedSingleTaps.offer(e);
return true;
}
@Override
public boolean onScroll (MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
// Queue motion events when scrolling
if (e2.getPointerCount() == 1 && e1.getPointerCount() == 1) {
previousScroll = isScrolling;
isScrolling = true;
queuedFingerHold.offer(new ScrollEvent(e2, startedScrolling()));
return true;
}
return false;
}
@Override
public boolean onDown(MotionEvent e) {
return true;
}
});
}
/**
* Polls for a tap.
*
* @return if a tap was queued, a MotionEvent for the tap. Otherwise null if no taps are queued.
*/
public MotionEvent poll() {
return queuedSingleTaps.poll();
}
public ScrollEvent holdPoll() { return queuedFingerHold.poll(); }
public boolean startedScrolling() {
return isScrolling && !previousScroll;
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
boolean val = gestureDetector.onTouchEvent(motionEvent);
// If finger is up + is scrolling: don't scroll anymore, and empty Touch Hold queue
if (motionEvent.getAction() == MotionEvent.ACTION_UP && isScrolling) {
previousScroll = true;
isScrolling = false;
queuedFingerHold.clear();
}
return val;
}
}
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