ViewTreeOnBackPressedDispatcherOwner.kt
/*
* Copyright 2021 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.
*/
@file:JvmName("ViewTreeOnBackPressedDispatcherOwner")
package androidx.activity
import android.view.View
/**
* Set the [OnBackPressedDispatcherOwner] associated with the given [View].
* Calls to [findViewTreeOnBackPressedDispatcherOwner] from this view or descendants will
* return [onBackPressedDispatcherOwner].
*
* This should only be called by constructs such as activities or dialogs that manage
* a view tree and handle the dispatch of the system back button. Callers
* should only set a [OnBackPressedDispatcherOwner] that will be *stable.*
*
* @param onBackPressedDispatcherOwner [OnBackPressedDispatcherOwner] associated with the [View]
*/
@JvmName("set")
fun View.setViewTreeOnBackPressedDispatcherOwner(
onBackPressedDispatcherOwner: OnBackPressedDispatcherOwner
) {
setTag(R.id.view_tree_on_back_pressed_dispatcher_owner, onBackPressedDispatcherOwner)
}
/**
* Retrieve the [OnBackPressedDispatcherOwner] associated with the given [View].
* This may be used to add a callback for the system back button.
*
* @return The [OnBackPressedDispatcherOwner] associated with this view and/or some subset
* of its ancestors
*/
@JvmName("get")
fun View.findViewTreeOnBackPressedDispatcherOwner(): OnBackPressedDispatcherOwner? {
return generateSequence(this) {
it.parent as? View
}.mapNotNull {
it.getTag(R.id.view_tree_on_back_pressed_dispatcher_owner) as? OnBackPressedDispatcherOwner
}.firstOrNull()
}