Merge "Automatic scroll when live content is updated" into main

import androidx.compose.runtime.remember

import androidx.compose.runtime.rememberCoroutineScope

import androidx.compose.runtime.setValue

import androidx.compose.runtime.snapshotFlow

import androidx.compose.ui.Alignment

import androidx.compose.ui.ExperimentalComposeUiApi

import androidx.compose.ui.Modifier

    val contentPadding = gridContentPadding(viewModel.isEditMode, toolbarSize)

    val contentOffset = beforeContentPadding(contentPadding).toOffset()

    ScrollOnNewSmartspaceEffect(viewModel, gridState)

    if (!viewModel.isEditMode) {

        ScrollOnUpdatedLiveContentEffect(communalContent, gridState)

    }

    Box(

        modifier =

    viewModel.signalUserInteraction()

}

/**

 * Observes communal content and scrolls to any added or updated live content, e.g. a new media

 * session is started, or a paused timer is resumed.

 */

@Composable

private fun ScrollOnNewSmartspaceEffect(

    viewModel: BaseCommunalViewModel,

    gridState: LazyGridState

private fun ScrollOnUpdatedLiveContentEffect(

    communalContent: List<CommunalContentModel>,

    gridState: LazyGridState,

) {

    val communalContent by viewModel.communalContent.collectAsState(initial = emptyList())

    var smartspaceCount by remember { mutableStateOf(0) }

    val coroutineScope = rememberCoroutineScope()

    val liveContentKeys = remember { mutableListOf<String>() }

    LaunchedEffect(communalContent) {

        snapshotFlow { gridState.firstVisibleItemIndex }

            .collect { index ->

                val existingSmartspaceCount = smartspaceCount

                smartspaceCount = communalContent.count { it.isSmartspace() }

                val firstIndex = communalContent.indexOfFirst { it.isSmartspace() }

        val prevLiveContentKeys = liveContentKeys.toList()

        liveContentKeys.clear()

        liveContentKeys.addAll(communalContent.filter { it.isLiveContent() }.map { it.key })

                // Scroll to the beginning of the smartspace area whenever the number of

                // smartspace elements grows

                if (

                    existingSmartspaceCount < smartspaceCount &&

                        !viewModel.isEditMode &&

                        index > firstIndex

                ) {

                    gridState.animateScrollToItem(firstIndex)

                }

        // Find the first updated content

        val indexOfFirstUpdatedContent =

            liveContentKeys.indexOfFirst { !prevLiveContentKeys.contains(it) }

        // Scroll if current position is behind the first updated content

        if (indexOfFirstUpdatedContent in 0..<gridState.firstVisibleItemIndex) {

            // Launching with a scope to prevent the job from being canceled in the case of a

            // recomposition during scrolling

            coroutineScope.launch { gridState.animateScrollToItem(indexOfFirstUpdatedContent) }

        }

    }

}

    fun isWidgetContent() = this is WidgetContent

    fun isSmartspace() = this is Smartspace

    fun isLiveContent() = this is Smartspace || this is Umo

}