fix(chat): keep sticky date header below pinned/overflow items and sync with visible messages

app/src/main/java/com/nextcloud/talk/chat/ChatActivity.kt

@@ -62,11 +62,19 @@ import androidx.compose.runtime.SideEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.ComposeView
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.dp
+import androidx.coordinatorlayout.widget.CoordinatorLayout
+import androidx.core.content.ContextCompat
 import androidx.core.content.FileProvider
 import androidx.core.content.PermissionChecker
 import androidx.core.content.PermissionChecker.PERMISSION_GRANTED
@@ -287,6 +295,7 @@ class ChatActivity :
     private val chatEmptyStateType = mutableStateOf<ChatEmptyStateType?>(null)
     private val upcomingEventUiState =
         mutableStateOf<ChatViewModel.UpcomingEventUIState>(ChatViewModel.UpcomingEventUIState.None)
+    private val overflowContainerHeightPx = mutableIntStateOf(0)
 
     private val startSelectContactForResult = registerForActivityResult(
         ActivityResultContracts
@@ -510,6 +519,10 @@ class ChatActivity :
 
         setUpcomingEventContent()
 
+        binding.chatOverflowContainer.viewTreeObserver.addOnGlobalLayoutListener {
+            overflowContainerHeightPx.intValue = binding.chatOverflowContainer.height
+        }
+
         lifecycleScope.launch {
             currentUserProvider.getCurrentUser()
                 .onSuccess { user ->
@@ -787,6 +800,9 @@ class ChatActivity :
                         openWhenDownloadState.value = (downloadingFileState.value.intersect(visibleIds).isNotEmpty())
                     }
 
+                    val overflowHeightDp = with(LocalDensity.current) {
+                        overflowContainerHeightPx.intValue.toDp()
+                    }
                     ChatView(
                         state = ChatViewState(
                             chatItems = uiState.items,
@@ -798,7 +814,8 @@ class ChatActivity :
                             highlightedSearchTerm = uiState.highlightedSearchTerm,
                             hasChatPermission = this::participantPermissions.isInitialized &&
                                 participantPermissions.hasChatPermission(),
-                            downloadingFileState = downloadingFileState.value
+                            downloadingFileState = downloadingFileState.value,
+                            stickyHeaderTopOffset = overflowHeightDp
                         ),
                         callbacks = ChatViewCallbacks(
                             onLoadMore = { messageId, direction -> loadMoreMessages(messageId, direction) },

app/src/main/java/com/nextcloud/talk/ui/chat/ChatView.kt

@@ -54,9 +54,11 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import com.nextcloud.talk.R
@@ -95,7 +97,8 @@ data class ChatViewState(
     val chatMode: ChatViewModel.ChatMode = ChatViewModel.ChatMode.DEFAULT_MODE,
     val highlightedMessageId: Int? = null,
     val highlightedSearchTerm: String? = null,
-    val downloadingFileState: List<String> = listOf()
+    val downloadingFileState: List<String> = listOf(),
+    val stickyHeaderTopOffset: Dp = 0.dp
 )
 
 data class ChatViewCallbacks(
@@ -263,23 +266,36 @@ fun ChatView(
     }
 
     // Sticky date header
-    val stickyDateHeaderText by remember(listState, state.chatItems) {
+    val density = LocalDensity.current
+    val overflowPx = with(density) { state.stickyHeaderTopOffset.roundToPx() }
+
+    val stickyDateHeaderText by remember(listState, state.chatItems, overflowPx) {
         derivedStateOf {
-            state.chatItems.getOrNull(
-                listState.layoutInfo.visibleItemsInfo.lastOrNull()?.index ?: 0
-            )?.let { item ->
-                when (item) {
-                    is ChatViewModel.ChatItem.MessageItem ->
-                        formatTime(item.uiMessage.timestamp * LONG_1000)
+            val visibleItems = listState.layoutInfo.visibleItemsInfo
+            val viewportEnd = listState.layoutInfo.viewportEndOffset
+            // In reverseLayout=true, offsets increase from bottom (newest) to top (oldest).
+            // An item's bottom edge is at screen Y = viewportEnd - offset; it is visible when that
+            // is >= overflowPx, i.e. offset <= viewportEnd - overflowPx.
+            val targetItem = if (overflowPx > 0) {
+                visibleItems.filter { it.offset <= viewportEnd - overflowPx }.lastOrNull()
+            } else {
+                visibleItems.lastOrNull()
+            }
+            targetItem?.let { itemInfo ->
+                state.chatItems.getOrNull(itemInfo.index)?.let { item ->
+                    when (item) {
+                        is ChatViewModel.ChatItem.MessageItem ->
+                            formatTime(item.uiMessage.timestamp * LONG_1000)
 
-                    is ChatViewModel.ChatItem.DateHeaderItem ->
-                        formatTime(item.date)
+                        is ChatViewModel.ChatItem.DateHeaderItem ->
+                            formatTime(item.date)
 
-                    is ChatViewModel.ChatItem.UnreadMessagesMarkerItem ->
-                        formatTime(item.date)
+                        is ChatViewModel.ChatItem.UnreadMessagesMarkerItem ->
+                            formatTime(item.date)
 
-                    else -> ""
-                }
+                        else -> ""
+                    }
+                } ?: ""
             } ?: ""
         }
     }
@@ -397,7 +413,7 @@ fun ChatView(
             text = stickyDateHeaderText,
             modifier = Modifier
                 .align(Alignment.TopCenter)
-                .padding(top = 2.dp)
+                .padding(top = state.stickyHeaderTopOffset + 2.dp)
                 .alpha(stickyDateHeaderAlpha)
         )
 

app/src/main/res/layout/activity_chat.xml

@@ -57,6 +57,7 @@
 
 
         <LinearLayout
+            android:id="@+id/chat_overflow_container"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:orientation="vertical">