1 /* 2 * Copyright (C) 2022 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.systemui.statusbar.gesture 18 19 import android.annotation.CallSuper 20 import android.os.Looper 21 import android.view.Choreographer 22 import android.view.InputEvent 23 import android.view.MotionEvent 24 import com.android.systemui.shared.system.InputChannelCompat 25 import com.android.systemui.shared.system.InputMonitorCompat 26 27 /** 28 * An abstract class to help detect gestures that occur anywhere on the display (not specific to a 29 * certain view). 30 * 31 * This class handles starting/stopping the gesture detection system as well as 32 * registering/unregistering callbacks for when gestures occur. Note that the class will only listen 33 * for gestures when there's at least one callback registered. 34 * 35 * Subclasses should implement [onInputEvent] to detect their specific gesture. Once a specific 36 * gesture is detected, they should call [onGestureDetected] (which will notify the callbacks). 37 */ 38 abstract class GenericGestureDetector( 39 private val tag: String, 40 private val displayId: Int, 41 ) { 42 /** 43 * Active callbacks, each associated with a tag. Gestures will only be monitored if 44 * [callbacks.size] > 0. 45 */ 46 private val callbacks: MutableMap<String, (MotionEvent) -> Unit> = mutableMapOf() 47 48 private var inputMonitor: InputMonitorCompat? = null 49 private var inputReceiver: InputChannelCompat.InputEventReceiver? = null 50 51 /** 52 * Adds a callback that will be triggered when the tap gesture is detected. 53 * 54 * The callback receive the last motion event in the gesture. 55 */ addOnGestureDetectedCallbacknull56 fun addOnGestureDetectedCallback(tag: String, callback: (MotionEvent) -> Unit) { 57 synchronized(callbacks) { 58 val callbacksWasEmpty = callbacks.isEmpty() 59 callbacks[tag] = callback 60 if (callbacksWasEmpty) { 61 startGestureListening() 62 } 63 } 64 } 65 66 /** Removes the callback. */ removeOnGestureDetectedCallbacknull67 fun removeOnGestureDetectedCallback(tag: String) { 68 synchronized(callbacks) { 69 callbacks.remove(tag) 70 if (callbacks.isEmpty()) { 71 stopGestureListening() 72 } 73 } 74 } 75 76 /** Triggered each time a touch event occurs (and at least one callback is registered). */ onInputEventnull77 abstract fun onInputEvent(ev: InputEvent) 78 79 /** 80 * Should be called by subclasses when their specific gesture is detected with the last motion 81 * event in the gesture. 82 */ 83 internal fun onGestureDetected(e: MotionEvent) { 84 val callbackValues = synchronized(callbacks) { ArrayList(callbacks.values) } 85 callbackValues.forEach { it.invoke(e) } 86 } 87 88 /** Start listening to touch events. */ 89 @CallSuper startGestureListeningnull90 internal open fun startGestureListening() { 91 stopGestureListening() 92 93 inputMonitor = 94 InputMonitorCompat(tag, displayId).also { 95 inputReceiver = 96 it.getInputReceiver( 97 Looper.getMainLooper(), 98 Choreographer.getInstance(), 99 this::onInputEvent, 100 ) 101 } 102 } 103 104 /** Stop listening to touch events. */ 105 @CallSuper stopGestureListeningnull106 internal open fun stopGestureListening() { 107 inputMonitor?.let { 108 inputMonitor = null 109 it.dispose() 110 } 111 inputReceiver?.let { 112 inputReceiver = null 113 it.dispose() 114 } 115 } 116 } 117