| /* |
| * Copyright 2016-2017 JetBrains s.r.o. |
| * |
| * 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 kotlinx.coroutines.experimental |
| |
| import org.w3c.dom.Window |
| |
| /** |
| * Converts an instance of [Window] to an implementation of [CoroutineDispatcher]. |
| */ |
| public fun Window.asCoroutineDispatcher(): CoroutineDispatcher = |
| @Suppress("UnsafeCastFromDynamic") |
| asDynamic().coroutineDispatcher ?: WindowDispatcher(this).also { |
| asDynamic().coroutineDispatcher = it |
| } |
| |
| /** |
| * Suspends coroutine until next JS animation frame and returns frame time on resumption. |
| * The time is consistent with [window.performance.now()][org.w3c.performance.Performance.now]. |
| * This function is cancellable. If the [Job] of the current coroutine is completed while this suspending |
| * function is waiting, this function immediately resumes with [CancellationException]. |
| */ |
| public suspend fun Window.awaitAnimationFrame(): Double = suspendCancellableCoroutine { cont -> |
| asWindowAnimationQueue().enqueue(cont) |
| } |
| |
| private fun Window.asWindowAnimationQueue(): WindowAnimationQueue = |
| @Suppress("UnsafeCastFromDynamic") |
| asDynamic().coroutineAnimationQueue ?: WindowAnimationQueue(this).also { |
| asDynamic().coroutineAnimationQueue = it |
| } |
| |
| private class WindowAnimationQueue(private val window: Window) { |
| private val dispatcher = window.asCoroutineDispatcher() |
| private var scheduled = false |
| private var current = Queue<CancellableContinuation<Double>>() |
| private var next = Queue<CancellableContinuation<Double>>() |
| private var timestamp = 0.0 |
| |
| fun enqueue(cont: CancellableContinuation<Double>) { |
| next.add(cont) |
| if (!scheduled) { |
| scheduled = true |
| window.requestAnimationFrame { ts -> |
| timestamp = ts |
| val prev = current |
| current = next |
| next = prev |
| scheduled = false |
| process() |
| } |
| } |
| } |
| |
| fun process() { |
| while(true) { |
| val element = current.poll() ?: return |
| with(element) { dispatcher.resumeUndispatched(timestamp) } |
| } |
| } |
| } |