fix: fix channel list pagination spinner (#375)

Signed-off-by: Sahil Kumar <[email protected]>

packages/stream_chat_flutter/lib/src/channel_list_view.dart

@@ -628,13 +628,14 @@ class _ChannelListViewState extends State<ChannelListView> {
               ),
             );
           }
-          return Container(
-            height: 100,
-            padding: EdgeInsets.all(32),
-            child: Center(
-              child: snapshot.data ? CircularProgressIndicator() : Container(),
-            ),
-          );
+          return snapshot.data
+              ? Center(
+                  child: Padding(
+                    padding: const EdgeInsets.all(16.0),
+                    child: const CircularProgressIndicator(),
+                  ),
+                )
+              : Offstage();
         });
   }
 

packages/stream_chat_flutter_core/lib/src/channels_bloc.dart

@@ -84,6 +84,8 @@ class ChannelsBlocState extends State<ChannelsBloc>
 
   final List<Channel> _hiddenChannels = [];
 
+  bool _paginationEnded = false;
+
   /// Calls [client.queryChannels] updating [queryChannelsLoading] stream
   Future<void> queryChannels({
     Map<String, dynamic> filter,
@@ -93,7 +95,9 @@ class ChannelsBlocState extends State<ChannelsBloc>
   }) async {
     final client = StreamChatCore.of(context).client;
 
-    if (_queryChannelsLoadingController.value == true) return;
+    if (_paginationEnded || _queryChannelsLoadingController.value == true) {
+      return;
+    }
 
     if (_channelsController.hasValue) {
       _queryChannelsLoadingController.add(true);
@@ -104,12 +108,14 @@ class ChannelsBlocState extends State<ChannelsBloc>
           paginationParams.offset == null ||
           paginationParams.offset == 0;
       final oldChannels = List<Channel>.from(channels ?? []);
+      var newChannels = <Channel>[];
       await for (final channels in client.queryChannels(
         filter: filter,
         sort: sortOptions,
         options: options,
         paginationParams: paginationParams,
       )) {
+        newChannels = channels;
         if (clear) {
           _channelsController.add(channels);
         } else {
@@ -121,6 +127,9 @@ class ChannelsBlocState extends State<ChannelsBloc>
           _queryChannelsLoadingController.sink.add(false);
         }
       }
+      if (newChannels.isEmpty || newChannels.length < paginationParams.limit) {
+        _paginationEnded = true;
+      }
     } catch (e, stk) {
       if (_channelsController.hasValue) {
         _queryChannelsLoadingController.addError(e, stk);

packages/stream_chat_flutter_core/lib/src/lazy_load_scroll_view.dart

@@ -47,6 +47,7 @@ class LazyLoadScrollView extends StatefulWidget {
 
 class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
   _LoadingStatus _loadMoreStatus = _LoadingStatus.stable;
+  double _scrollPosition = 0;
 
   @override
   Widget build(BuildContext context) =>
@@ -84,15 +85,21 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
 
       final extentBefore = notification.metrics.extentBefore;
       final extentAfter = notification.metrics.extentAfter;
+      final scrollingDown = _scrollPosition < pixels;
 
-      if (extentAfter <= scrollOffset) {
-        _onEndOfPage();
-        return true;
-      }
-      if (extentBefore <= scrollOffset) {
-        _onStartOfPage();
-        return true;
+      if (scrollingDown) {
+        if (extentAfter <= scrollOffset) {
+          _onEndOfPage();
+          return true;
+        }
+      } else {
+        if (extentBefore <= scrollOffset) {
+          _onStartOfPage();
+          return true;
+        }
       }
+
+      _scrollPosition = pixels;
     }
     if (notification is OverscrollNotification) {
       if (notification.overscroll > 0) {
@@ -108,8 +115,8 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
 
   void _onEndOfPage() {
     if (_loadMoreStatus != null && _loadMoreStatus == _LoadingStatus.stable) {
-      _loadMoreStatus = _LoadingStatus.loading;
       if (widget.onEndOfPage != null) {
+        _loadMoreStatus = _LoadingStatus.loading;
         widget.onEndOfPage().whenComplete(() {
           _loadMoreStatus = _LoadingStatus.stable;
         });
@@ -119,8 +126,8 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
 
   void _onStartOfPage() {
     if (_loadMoreStatus != null && _loadMoreStatus == _LoadingStatus.stable) {
-      _loadMoreStatus = _LoadingStatus.loading;
       if (widget.onStartOfPage != null) {
+        _loadMoreStatus = _LoadingStatus.loading;
         widget.onStartOfPage().whenComplete(() {
           _loadMoreStatus = _LoadingStatus.stable;
         });

packages/stream_chat_flutter_core/test/channel_list_core_test.dart

@@ -9,7 +9,7 @@ import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 import 'mocks.dart';
 
 void main() {
-  const pagination = PaginationParams(offset: 0, limit: 25);
+  const pagination = PaginationParams(offset: 0, limit: 3);
 
   List<Channel> _generateChannels(
     StreamChatClient client, {
@@ -180,6 +180,7 @@ void main() {
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) =>
             Container(key: errorWidgetKey),
+        pagination: pagination,
       );
 
       final mockClient = MockClient();
@@ -227,6 +228,7 @@ void main() {
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Container(key: emptyWidgetKey),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
+        pagination: pagination,
       );
 
       final mockClient = MockClient();
@@ -274,6 +276,7 @@ void main() {
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
+        pagination: pagination,
       );
 
       final mockClient = MockClient();
@@ -329,6 +332,7 @@ void main() {
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
+        pagination: pagination,
       );
 
       final mockClient = MockClient();