PinnableContainer.kt
/*
* Copyright 2022 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.layout
import androidx.compose.runtime.Stable
import androidx.compose.runtime.compositionLocalOf
/**
* Parent layouts with pinning support for the children content will provide the current
* [PinnableContainer] via this composition local.
*/
val LocalPinnableContainer = compositionLocalOf<PinnableContainer?> { null }
/**
* Represents a container which can be pinned by some of its parents.
*
* For example in lists which only compose visible items it means this item will be kept
* composed even when it will be scrolled out of the view.
*/
@Stable
interface PinnableContainer {
/**
* Pin the current container when its content needs to be kept alive, for example when it has
* focus or user is interacting with it in some other way.
*
* Don't forget to call [PinnedHandle.unpin] when this content is not needed anymore.
*/
fun pin(): PinnedHandle
/**
* This is an object returned by [pin] which allows to unpin the content.
*/
fun interface PinnedHandle {
/**
* Unpin the container associated with this handle.
*/
fun unpin()
}
}