| /* |
| * 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.runtime.livedata |
| |
| import androidx.compose.runtime.Composable |
| import androidx.compose.runtime.State |
| import androidx.compose.runtime.onPreCommit |
| import androidx.compose.runtime.state |
| import androidx.lifecycle.Lifecycle |
| import androidx.lifecycle.LifecycleOwner |
| import androidx.lifecycle.LiveData |
| import androidx.lifecycle.Observer |
| import androidx.ui.core.LifecycleOwnerAmbient |
| |
| /** |
| * Starts observing this [LiveData] and represents its values via [State]. Every time there would |
| * be new value posted into the [LiveData] the returned [State] will be updated causing |
| * recomposition of every [State.value] usage. |
| * |
| * The inner observer will automatically be removed when this composable disposes or the current |
| * [LifecycleOwner] moves to the [Lifecycle.State.DESTROYED] state. |
| * |
| * @sample androidx.compose.runtime.livedata.samples.LiveDataSample |
| */ |
| @Suppress("NOTHING_TO_INLINE") |
| @Composable |
| inline fun <T> LiveData<T>.observeAsState(): State<T?> = observeAsState(value) |
| |
| /** |
| * Starts observing this [LiveData] and represents its values via [State]. Every time there would |
| * be new value posted into the [LiveData] the returned [State] will be updated causing |
| * recomposition of every [State.value] usage. |
| * |
| * The inner observer will automatically be removed when this composable disposes or the current |
| * [LifecycleOwner] moves to the [Lifecycle.State.DESTROYED] state. |
| * |
| * @sample androidx.compose.runtime.livedata.samples.LiveDataWithInitialSample |
| */ |
| @Composable |
| fun <R, T : R> LiveData<T>.observeAsState(initial: R): State<R> { |
| val lifecycleOwner = LifecycleOwnerAmbient.current |
| val state = state { initial } |
| onPreCommit(this, lifecycleOwner) { |
| val observer = Observer<T> { state.value = it } |
| observe(lifecycleOwner, observer) |
| onDispose { removeObserver(observer) } |
| } |
| return state |
| } |