WindowInfoRepository.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.
*/
package androidx.window.layout
import android.app.Activity
import android.os.Looper
import androidx.annotation.RestrictTo
import androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP
import androidx.window.R
import kotlinx.coroutines.flow.Flow
/**
* An interface to provide all the relevant info about a [android.view.Window].
*/
public interface WindowInfoRepository {
/**
* Returns a [Flow] for consuming the current [WindowMetrics] according to the current
* system state.
*
* The metrics describe the size of the area the window would occupy with
* [MATCH_PARENT][android.view.WindowManager.LayoutParams.MATCH_PARENT] width and height
* and any combination of flags that would allow the window to extend behind display cutouts.
*
* The value of this is based on the **current** windowing state of the system. For
* example, for activities in multi-window mode, the metrics returned are based on the
* current bounds that the user has selected for the [Activity][android.app.Activity]'s
* window.
*
* @see android.view.WindowManager.getCurrentWindowMetrics
*/
public val currentWindowMetrics: Flow<WindowMetrics>
/**
* A [Flow] of [WindowLayoutInfo] that contains all the available features.
*/
public val windowLayoutInfo: Flow<WindowLayoutInfo>
public companion object {
private var decorator: WindowInfoRepositoryDecorator = EmptyDecorator
/**
* Provide an instance of [WindowInfoRepository] that is associated to the given [Activity]
*/
@JvmName("getOrCreate")
@JvmStatic
public fun Activity.windowInfoRepository(): WindowInfoRepository {
val taggedRepo = getTag(R.id.androidx_window_activity_scope) as? WindowInfoRepository
val repo = taggedRepo ?: getOrCreateTag(R.id.androidx_window_activity_scope) {
WindowInfoRepositoryImpl(
this,
WindowMetricsCalculatorCompat,
ExtensionWindowBackend.getInstance(this)
)
}
return decorator.decorate(repo)
}
private inline fun <reified T> Activity.getTag(id: Int): T? {
return window.decorView.getTag(id) as? T
}
/**
* Checks to see if an object of type [T] is associated with the tag [id]. If it is
* available then it is returned. Otherwise set an object crated using the [producer] and
* return that value.
* @return object associated with the tag.
*/
private inline fun <reified T> Activity.getOrCreateTag(id: Int, producer: () -> T): T {
return (window.decorView.getTag(id) as? T) ?: run {
assert(Looper.getMainLooper() == Looper.myLooper())
val value = producer()
window.decorView.setTag(id, value)
value
}
}
@JvmStatic
@RestrictTo(LIBRARY_GROUP)
public fun overrideDecorator(overridingDecorator: WindowInfoRepositoryDecorator) {
decorator = overridingDecorator
}
@JvmStatic
@RestrictTo(LIBRARY_GROUP)
public fun reset() {
decorator = EmptyDecorator
}
}
}
@RestrictTo(LIBRARY_GROUP)
public interface WindowInfoRepositoryDecorator {
/**
* Returns an instance of [WindowInfoRepository] associated to the [Activity]
*/
@RestrictTo(LIBRARY_GROUP)
public fun decorate(repository: WindowInfoRepository): WindowInfoRepository
}
private object EmptyDecorator : WindowInfoRepositoryDecorator {
override fun decorate(repository: WindowInfoRepository): WindowInfoRepository {
return repository
}
}