Merge pull request #108 from GetStream/feature/messageListView

add scroll to bottom fab

lib/src/message_list_view.dart

@@ -97,6 +97,7 @@ class MessageListView extends StatefulWidget {
   /// Instantiate a new MessageListView
   MessageListView({
     Key key,
+    this.showScrollToBottom = true,
     this.messageBuilder,
     this.parentMessageBuilder,
     this.parentMessage,
@@ -120,6 +121,9 @@ class MessageListView extends StatefulWidget {
   /// By default it calls [Navigator.push] using the widget built using [threadBuilder]
   final ThreadTapCallback onThreadTap;
 
+  /// If true will show a scroll to bottom message when there are new messages and the scroll offset is not zero
+  final bool showScrollToBottom;
+
   /// Parent message in case of a thread
   final Message parentMessage;
 
@@ -144,132 +148,193 @@ class _MessageListViewState extends State<MessageListView> {
   List<Message> _messages = [];
   List<Message> _newMessageList = [];
   Function _onThreadTap;
+  bool _showScrollToBottom = false;
 
   @override
   Widget build(BuildContext context) {
     final streamChannel = StreamChannel.of(context);
 
     /// TODO: find a better solution when (https://github.com/flutter/flutter/issues/21023) is fixed
-    return NotificationListener<ScrollNotification>(
+    return Stack(
-      onNotification: (_) {
+      children: [
-        if (_scrollController.offset < 150 && _newMessageList.isNotEmpty) {
+        NotificationListener<ScrollNotification>(
-          setState(() {
+          onNotification: (_) {
-            _messages.insertAll(0, _newMessageList);
+            if (_scrollController.offset < 150 && _newMessageList.isNotEmpty) {
-            _newMessageList.clear();
+              setState(() {
-          });
+                _messages.insertAll(0, _newMessageList);
-        }
+                _newMessageList.clear();
-        return true;
+              });
-      },
+            }
-      child: ListView.custom(
+            return true;
-        key: Key('messageListView'),
+          },
-        physics: widget.scrollPhysics,
+          child: ListView.custom(
-        keyboardDismissBehavior: widget.keyboardDismissBehavior,
+            key: Key('messageListView'),
-        controller: _scrollController,
+            physics: widget.scrollPhysics,
-        reverse: true,
+            keyboardDismissBehavior: widget.keyboardDismissBehavior,
-        childrenDelegate: SliverChildBuilderDelegate(
+            controller: _scrollController,
-          (context, i) {
+            reverse: true,
-            if (i == _messages.length + 1) {
+            childrenDelegate: SliverChildBuilderDelegate(
-              if (widget.parentMessage != null) {
+              (context, i) {
-                if (widget.parentMessageBuilder != null) {
+                if (i == _messages.length + 1) {
-                  return widget.parentMessageBuilder(
+                  if (widget.parentMessage != null) {
+                    if (widget.parentMessageBuilder != null) {
+                      return widget.parentMessageBuilder(
+                        context,
+                        widget.parentMessage,
+                      );
+                    } else {
+                      return Column(
+                        crossAxisAlignment: CrossAxisAlignment.stretch,
+                        children: <Widget>[
+                          buildParentMessage(widget.parentMessage),
+                          Padding(
+                            padding: const EdgeInsets.symmetric(horizontal: 32),
+                            child: Container(
+                              padding: const EdgeInsets.all(8),
+                              child: Text(
+                                'Start of thread',
+                                textAlign: TextAlign.center,
+                              ),
+                              color:
+                                  Theme.of(context).accentColor.withAlpha(50),
+                            ),
+                          ),
+                        ],
+                      );
+                    }
+                  } else {
+                    return SizedBox();
+                  }
+                }
+
+                if (i == _messages.length) {
+                  return _buildLoadingIndicator(streamChannel);
+                }
+                final message = _messages[i];
+                final nextMessage = i > 0 ? _messages[i - 1] : null;
+
+                Widget messageWidget;
+
+                if (i == 0) {
+                  messageWidget = _buildBottomMessage(
                     context,
-                    widget.parentMessage,
+                    message,
+                    _messages,
+                    streamChannel,
+                  );
+                } else if (i == _messages.length - 1) {
+                  messageWidget = _buildTopMessage(
+                    context,
+                    message,
+                    _messages,
+                    streamChannel,
                   );
                 } else {
+                  if (widget.messageBuilder != null) {
+                    messageWidget = Builder(
+                      key: ValueKey<String>('MESSAGE-${message.id}'),
+                      builder: (_) => widget.messageBuilder(
+                          context,
+                          MessageDetails(
+                            context,
+                            message,
+                            _messages,
+                            i,
+                          ),
+                          _messages),
+                    );
+                  } else {
+                    messageWidget = buildMessage(message, _messages, i);
+                  }
+                }
+
+                if (nextMessage != null &&
+                    !Jiffy(message.createdAt.toLocal())
+                        .isSame(nextMessage.createdAt.toLocal(), Units.DAY)) {
                   return Column(
                     crossAxisAlignment: CrossAxisAlignment.stretch,
                     children: <Widget>[
-                      buildParentMessage(widget.parentMessage),
+                      messageWidget,
                       Padding(
-                        padding: const EdgeInsets.symmetric(horizontal: 32),
+                        padding: const EdgeInsets.symmetric(vertical: 12.0),
-                        child: Container(
+                        child: widget.dateDividerBuilder != null
-                          padding: const EdgeInsets.all(8),
+                            ? widget.dateDividerBuilder(
-                          child: Text(
+                                nextMessage.createdAt.toLocal())
-                            'Start of thread',
+                            : DateDivider(
-                            textAlign: TextAlign.center,
+                                dateTime: nextMessage.createdAt.toLocal(),
-                          ),
+                              ),
-                          color: Theme.of(context).accentColor.withAlpha(50),
-                        ),
                       ),
                     ],
                   );
                 }
-              } else {
-                return SizedBox();
-              }
-            }
 
-            if (i == _messages.length) {
+                return messageWidget;
-              return _buildLoadingIndicator(streamChannel);
+              },
-            }
+              childCount: _messages.length + 2,
-            final message = _messages[i];
+              findChildIndexCallback: (key) {
-            final nextMessage = i > 0 ? _messages[i - 1] : null;
+                final ValueKey<String> valueKey = key;
-
+                final index = _messages
-            Widget messageWidget;
+                    .indexWhere((m) => 'MESSAGE-${m.id}' == valueKey.value);
-
+                return index != -1 ? index : null;
-            if (i == 0) {
+              },
-              messageWidget = _buildBottomMessage(
+            ),
-                context,
+          ),
-                message,
-                _messages,
-                streamChannel,
-              );
-            } else if (i == _messages.length - 1) {
-              messageWidget = _buildTopMessage(
-                context,
-                message,
-                _messages,
-                streamChannel,
-              );
-            } else {
-              if (widget.messageBuilder != null) {
-                messageWidget = Builder(
-                  key: ValueKey<String>('MESSAGE-${message.id}'),
-                  builder: (_) => widget.messageBuilder(
-                      context,
-                      MessageDetails(
-                        context,
-                        message,
-                        _messages,
-                        i,
-                      ),
-                      _messages),
-                );
-              } else {
-                messageWidget = buildMessage(message, _messages, i);
-              }
-            }
-
-            if (nextMessage != null &&
-                !Jiffy(message.createdAt.toLocal())
-                    .isSame(nextMessage.createdAt.toLocal(), Units.DAY)) {
-              return Column(
-                crossAxisAlignment: CrossAxisAlignment.stretch,
-                children: <Widget>[
-                  messageWidget,
-                  Padding(
-                    padding: const EdgeInsets.symmetric(vertical: 12.0),
-                    child: widget.dateDividerBuilder != null
-                        ? widget
-                            .dateDividerBuilder(nextMessage.createdAt.toLocal())
-                        : DateDivider(
-                            dateTime: nextMessage.createdAt.toLocal(),
-                          ),
-                  ),
-                ],
-              );
-            }
-
-            return messageWidget;
-          },
-          childCount: _messages.length + 2,
-          findChildIndexCallback: (key) {
-            final ValueKey<String> valueKey = key;
-            final index = _messages
-                .indexWhere((m) => 'MESSAGE-${m.id}' == valueKey.value);
-            return index != -1 ? index : null;
-          },
         ),
+        if (widget.showScrollToBottom)
+          StreamBuilder<Event>(
+              stream: streamChannel.channel.on(
+                EventType.messageNew,
+              ),
+              builder: (context, _) {
+                if (!_showScrollToBottom ||
+                    streamChannel.channel.state.unreadCount == 0) {
+                  return SizedBox();
+                }
+                return _buildScrollToBottom(streamChannel);
+              }),
+      ],
+    );
+  }
+
+  Widget _buildScrollToBottom(StreamChannelState streamChannel) {
+    return Positioned(
+      bottom: 8,
+      right: 8,
+      width: 40,
+      height: 40,
+      child: Stack(
+        clipBehavior: Clip.none,
+        children: [
+          FloatingActionButton(
+            backgroundColor: Colors.white,
+            child: Icon(
+              StreamIcons.down,
+              color: Colors.black,
+            ),
+            onPressed: () {
+              Future.delayed(Duration(milliseconds: 500), () {
+                setState(() {
+                  _showScrollToBottom = false;
+                });
+              });
+              _scrollController.animateTo(
+                0,
+                duration: Duration(seconds: 1),
+                curve: Curves.easeInOut,
+              );
+            },
+          ),
+          Positioned(
+            width: 20,
+            height: 20,
+            left: 10,
+            top: -10,
+            child: CircleAvatar(
+              radius: 20,
+              child: Text(streamChannel.channel.state.unreadCount.toString()),
+            ),
+          ),
+        ],
       ),
     );
   }
@@ -381,6 +446,9 @@ class _MessageListViewState extends State<MessageListView> {
           }
         }
         _bottomWasVisible = isVisible;
+        setState(() {
+          _showScrollToBottom = !isVisible;
+        });
       },
       child: messageWidget,
     );

lib/src/stream_chat_theme.dart

@@ -3,10 +3,9 @@ import 'package:stream_chat/stream_chat.dart';
 import 'package:stream_chat_flutter/src/channel_header.dart';
 import 'package:stream_chat_flutter/src/channel_preview.dart';
 import 'package:stream_chat_flutter/src/message_input.dart';
+import 'package:stream_chat_flutter/src/reaction_icon.dart';
 import 'package:stream_chat_flutter/src/stream_icons.dart';
 
-import 'reaction_asset.dart';
-
 /// Inherited widget providing the [StreamChatThemeData] to the widget tree
 class StreamChatTheme extends InheritedWidget {
   final StreamChatThemeData data;