CompositionLocals.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.glance
import android.content.Context
import androidx.compose.runtime.Composable
import androidx.compose.runtime.staticCompositionLocalOf
import androidx.compose.ui.unit.DpSize
import androidx.datastore.preferences.core.Preferences
import androidx.glance.state.GlanceStateDefinition
/**
* Size of the glance view being generated.
*
* The glance view will have at least that much space to be displayed. The exact meaning may
* changed depending on the surface and how it is configured.
*/
val LocalSize = staticCompositionLocalOf<DpSize> { error("No default size") }
/**
* Context of application when generating the glance view.
*/
val LocalContext = staticCompositionLocalOf<Context> { error("No default context") }
/**
* Local view state, defined in surface implementation. A customizable store for view specific state
* data.
*/
val LocalState =
staticCompositionLocalOf<Any?> { null }
/**
* Unique Id for the glance view being generated by the current composition.
*/
val LocalGlanceId = staticCompositionLocalOf<GlanceId> { error("No default glance id") }
/**
* Retrieves the current customizable store for view specific state data as defined by
* [GlanceStateDefinition] in the surface implementation.
*
* @return the current store of the provided type [T]
*/
@Composable
inline fun <reified T> currentState(): T = LocalState.current as T
/**
* Retrieves the current [Preferences] value of the provided [Preferences.Key] from the current
* state when [Preferences] store is used as [GlanceStateDefinition] in the surface implementation.
*
* @param key the [Preferences.Key] to retrieve its value
* @return the stored value or null if not available.
*/
@Composable
inline fun <reified T> currentState(key: Preferences.Key<T>): T? =
currentState<Preferences>()[key]