activity/activity-ktx/src/main/java/androidx/activity/OnBackPressedDispatcher.kt

/*
 * Copyright 2019 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.lifecycle.LifecycleOwner

/**
 * Create and add a new [OnBackPressedCallback] that calls [onBackPressed] in
 * [OnBackPressedCallback.handleOnBackPressed].
 *
 * If an [owner] is specified, the callback will only be added when the Lifecycle is
 * [androidx.lifecycle.Lifecycle.State.STARTED].
 *
 * A default [enabled] state can be supplied.
 */
public fun OnBackPressedDispatcher.addCallback(
    owner: LifecycleOwner? = null,
    enabled: Boolean = true,
    onBackPressed: OnBackPressedCallback.() -> Unit
): OnBackPressedCallback {
    val callback = object : OnBackPressedCallback(enabled) {
        override fun handleOnBackPressed() {
            onBackPressed()
        }
    }
    if (owner != null) {
        addCallback(owner, callback)
    } else {
        addCallback(callback)
    }
    return callback
}