| /* |
| * Copyright 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 androidx.compose.ui.platform |
| |
| import androidx.compose.runtime.snapshots.Snapshot |
| import androidx.compose.ui.platform.GlobalSnapshotManager.ensureStarted |
| import kotlinx.coroutines.CoroutineScope |
| import kotlinx.coroutines.channels.Channel |
| import kotlinx.coroutines.channels.consumeEach |
| import kotlinx.coroutines.launch |
| import java.util.concurrent.atomic.AtomicBoolean |
| |
| /** |
| * Platform-specific mechanism for starting a monitor of global snapshot state writes |
| * in order to schedule the periodic dispatch of snapshot apply notifications. |
| * This process should remain platform-specific; it is tied to the threading and update model of |
| * a particular platform and framework target. |
| * |
| * Composition bootstrapping mechanisms for a particular platform/framework should call |
| * [ensureStarted] during setup to initialize periodic global snapshot notifications. |
| * For Android, these notifications are always sent on [AndroidUiDispatcher.Main]. Other platforms |
| * may establish different policies for these notifications. |
| */ |
| internal object GlobalSnapshotManager { |
| private val started = AtomicBoolean(false) |
| |
| fun ensureStarted() { |
| if (started.compareAndSet(false, true)) { |
| val channel = Channel<Unit>(Channel.CONFLATED) |
| CoroutineScope(AndroidUiDispatcher.Main).launch { |
| channel.consumeEach { |
| Snapshot.sendApplyNotifications() |
| } |
| } |
| Snapshot.registerGlobalWriteObserver { |
| channel.trySend(Unit) |
| } |
| } |
| } |
| } |