WindowManager.kt
/*
* 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.Composable
import androidx.compose.runtime.ExperimentalComposeApi
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.Stable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.runtime.snapshots.snapshotFlow
import kotlinx.coroutines.InternalCoroutinesApi
import kotlinx.coroutines.flow.collect
/**
* Provides information about the Window that is hosting this compose hierarchy.
*/
@Stable
interface WindowManager {
/**
* Indicates whether the window hosting this compose hierarchy is in focus.
*
* When there are multiple windows visible, either in a multi-window environment or if a
* popup or dialog is visible, this property can be used to determine if the current window
* is in focus.
*/
val isWindowFocused: Boolean
}
/**
* Provides a callback that is called whenever the window gains or loses focus.
*/
@OptIn(
ExperimentalComposeApi::class,
InternalCoroutinesApi::class
)
@Composable
fun WindowFocusObserver(onWindowFocusChanged: (isWindowFocused: Boolean) -> Unit) {
val windowManager = AmbientWindowManager.current
val callback = rememberUpdatedState(onWindowFocusChanged)
LaunchedEffect(windowManager) {
snapshotFlow { windowManager.isWindowFocused }.collect { callback.value(it) }
}
}
internal class WindowManagerImpl : WindowManager {
private val _isWindowFocused = mutableStateOf(false)
override var isWindowFocused: Boolean
set(value) { _isWindowFocused.value = value }
get() = _isWindowFocused.value
}