| /* |
| * Copyright 2018 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.activity |
| |
| import androidx.annotation.MainThread |
| import java.util.concurrent.CopyOnWriteArrayList |
| |
| /** |
| * Class for handling [OnBackPressedDispatcher.onBackPressed] callbacks without |
| * strongly coupling that implementation to a subclass of [ComponentActivity]. |
| * |
| * This class maintains its own [enabled state][isEnabled]. Only when this callback |
| * is enabled will it receive callbacks to [handleOnBackPressed]. |
| * |
| * Note that the enabled state is an additional layer on top of the |
| * [androidx.lifecycle.LifecycleOwner] passed to |
| * [OnBackPressedDispatcher.addCallback] |
| * which controls when the callback is added and removed to the dispatcher. |
| * |
| * By calling [remove], this callback will be removed from any |
| * [OnBackPressedDispatcher] it has been added to. It is strongly recommended |
| * to instead disable this callback to handle temporary changes in state. |
| * |
| * @param enabled The default enabled state for this callback. |
| * |
| * @see OnBackPressedDispatcher |
| */ |
| abstract class OnBackPressedCallback(enabled: Boolean) { |
| /** |
| * The enabled state of the callback. Only when this callback |
| * is enabled will it receive callbacks to [handleOnBackPressed]. |
| * |
| * Note that the enabled state is an additional layer on top of the |
| * [androidx.lifecycle.LifecycleOwner] passed to |
| * [OnBackPressedDispatcher.addCallback] |
| * which controls when the callback is added and removed to the dispatcher. |
| */ |
| @get:MainThread |
| @set:MainThread |
| var isEnabled: Boolean = enabled |
| set(value) { |
| field = value |
| enabledChangedCallback?.invoke() |
| } |
| |
| private val cancellables = CopyOnWriteArrayList<Cancellable>() |
| internal var enabledChangedCallback: (() -> Unit)? = null |
| |
| /** |
| * Removes this callback from any [OnBackPressedDispatcher] it is currently |
| * added to. |
| */ |
| @MainThread |
| fun remove() = cancellables.forEach { it.cancel() } |
| |
| /** |
| * Callback for handling the system UI generated equivalent to |
| * [OnBackPressedDispatcher.dispatchOnBackStarted]. |
| * |
| * This will only be called by the framework on API 34 and above. |
| */ |
| @Suppress("CallbackMethodName") /* mirror handleOnBackPressed local style */ |
| @MainThread |
| open fun handleOnBackStarted(backEvent: BackEventCompat) {} |
| |
| /** |
| * Callback for handling the system UI generated equivalent to |
| * [OnBackPressedDispatcher.dispatchOnBackProgressed]. |
| * |
| * This will only be called by the framework on API 34 and above. |
| */ |
| @Suppress("CallbackMethodName") /* mirror handleOnBackPressed local style */ |
| @MainThread |
| open fun handleOnBackProgressed(backEvent: BackEventCompat) {} |
| |
| /** |
| * Callback for handling the [OnBackPressedDispatcher.onBackPressed] event. |
| */ |
| @MainThread |
| abstract fun handleOnBackPressed() |
| |
| /** |
| * Callback for handling the system UI generated equivalent to |
| * [OnBackPressedDispatcher.dispatchOnBackCancelled]. |
| * |
| * This will only be called by the framework on API 34 and above. |
| */ |
| @Suppress("CallbackMethodName") /* mirror handleOnBackPressed local style */ |
| @MainThread |
| open fun handleOnBackCancelled() {} |
| |
| @JvmName("addCancellable") |
| internal fun addCancellable(cancellable: Cancellable) { |
| cancellables.add(cancellable) |
| } |
| |
| @JvmName("removeCancellable") |
| internal fun removeCancellable(cancellable: Cancellable) { |
| cancellables.remove(cancellable) |
| } |
| } |
