Adjust scroll position when smartspace content appears.

This changelist scrolls the communal hub to the beginning of the
smartspace section whenever the smartspace content grows.

Test: Manual. Verified scroll position is updated when new smartspace
timers are added.
Flag: ACONFIG com.android.systemui.communal_hub STAGING
Fixes: 325635703

Change-Id: I1b74720d9a67f32ca0ab0dcb41898884f842e19b

2 files changed, 34 insertions, 0 deletions

diff --git a/packages/SystemUI/compose/features/src/com/android/systemui/communal/ui/compose/CommunalHub.kt b/packages/SystemUI/compose/features/src/com/android/systemui/communal/ui/compose/CommunalHub.kt
index 515c8169f1c4..abfba3d6db86 100644
--- a/packages/SystemUI/compose/features/src/com/android/systemui/communal/ui/compose/CommunalHub.kt
+++ b/packages/SystemUI/compose/features/src/com/android/systemui/communal/ui/compose/CommunalHub.kt
@@ -66,6 +66,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.State
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.derivedStateOf
@@ -74,6 +75,7 @@ import androidx.compose.runtime.mutableStateOf
 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
@@ -152,6 +154,8 @@ fun CommunalHub(
     val contentPadding = gridContentPadding(viewModel.isEditMode, toolbarSize)
     val contentOffset = beforeContentPadding(contentPadding).toOffset()
 
+    ScrollOnNewSmartspaceEffect(viewModel, gridState)
+
     Box(
         modifier =
             modifier
@@ -279,6 +283,34 @@ fun CommunalHub(
     }
 }
 
+@Composable
+private fun ScrollOnNewSmartspaceEffect(
+    viewModel: BaseCommunalViewModel,
+    gridState: LazyGridState
+) {
+    val communalContent by viewModel.communalContent.collectAsState(initial = emptyList())
+    var smartspaceCount by remember { mutableStateOf(0) }
+
+    LaunchedEffect(communalContent) {
+        snapshotFlow { gridState.firstVisibleItemIndex }
+            .collect { index ->
+                val existingSmartspaceCount = smartspaceCount
+                smartspaceCount = communalContent.count { it.isSmartspace() }
+                val firstIndex = communalContent.indexOfFirst { it.isSmartspace() }
+
+                // 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)
+                }
+            }
+    }
+}
+
 @OptIn(ExperimentalFoundationApi::class)
 @Composable
 private fun ColumnScope.CommunalHubLazyGrid(
diff --git a/packages/SystemUI/src/com/android/systemui/communal/domain/model/CommunalContentModel.kt b/packages/SystemUI/src/com/android/systemui/communal/domain/model/CommunalContentModel.kt
index c64f666ebf10..12576d466823 100644
--- a/packages/SystemUI/src/com/android/systemui/communal/domain/model/CommunalContentModel.kt
+++ b/packages/SystemUI/src/com/android/systemui/communal/domain/model/CommunalContentModel.kt
@@ -152,4 +152,6 @@ sealed interface CommunalContentModel {
     }
 
     fun isWidgetContent() = this is WidgetContent
+
+    fun isSmartspace() = this is Smartspace
 }