[ChannelListHeader] Refactor, Add support for trailing, leading widget taps.

lib/src/channel_list_header.dart

@@ -7,22 +7,57 @@ import 'package:stream_chat_flutter/stream_chat_flutter.dart';
 
 import 'stream_chat.dart';
 
-typedef TitleBuilder = Widget Function(
+typedef _TitleBuilder = Widget Function(
   BuildContext context,
   ConnectionStatus status,
   Client client,
 );
 
+///
+/// It shows the current [Client] status.
+///
+/// ```dart
+/// class MyApp extends StatelessWidget {
+///   final Client client;
+///
+///   MyApp(this.client);
+///
+///   @override
+///   Widget build(BuildContext context) {
+///     return MaterialApp(
+///       home: StreamChat(
+///         client: client,
+///         child: Scaffold(
+///             appBar: ChannelListHeader(),
+///           ),
+///         ),
+///     );
+///   }
+/// }
+/// ```
+///
+/// Usually you would use this widget as an [AppBar] inside a [Scaffold].
+/// However you can also use it as a normal widget.
+///
+/// The widget components render the ui based on the first ancestor of type [StreamChatTheme] and on its [ChannelTheme.channelHeaderTheme] property.
+/// Modify it to change the widget appearance.
 class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
+  /// Instantiates a ChannelListHeader
   const ChannelListHeader({
     Key key,
     this.client,
     this.titleBuilder,
+    this.onUserAvatarTap,
+    this.onNewChatButtonTap,
   }) : super(key: key);
 
   final Client client;
 
-  final TitleBuilder titleBuilder;
+  final _TitleBuilder titleBuilder;
+
+  final Function(User) onUserAvatarTap;
+
+  final VoidCallback onNewChatButtonTap;
 
   @override
   Widget build(BuildContext context) {
@@ -37,7 +72,8 @@ class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
       leading: Center(
         child: UserAvatar(
           user: user,
-          onTap: (_) => Scaffold.of(context).openDrawer(),
+          onTap: onUserAvatarTap ?? (_) => Scaffold.of(context).openDrawer(),
+          borderRadius: BorderRadius.circular(20),
           constraints: BoxConstraints.tightFor(
             height: 40,
             width: 40,
@@ -68,7 +104,7 @@ class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
                 );
               },
             ),
-            onPressed: () {},
+            onPressed: onNewChatButtonTap,
           ),
         )
       ],
@@ -80,11 +116,11 @@ class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
           }
           switch (status) {
             case ConnectionStatus.connected:
-              return _buildConnectedTitleState();
+              return _buildConnectedTitleState(context);
             case ConnectionStatus.connecting:
-              return _buildConnectingTitleState();
+              return _buildConnectingTitleState(context);
             case ConnectionStatus.disconnected:
-              return _buildDisconnectedTitleState(_client);
+              return _buildDisconnectedTitleState(context, _client);
             default:
               return Offstage();
           }
@@ -93,16 +129,19 @@ class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
     );
   }
 
-  Widget _buildConnectedTitleState() => Text(
+  Widget _buildConnectedTitleState(BuildContext context) => Text(
         'Stream Chat',
-        style: TextStyle(
-          fontSize: 16,
-          fontWeight: FontWeight.bold,
-          color: Colors.black,
-        ),
+        style: StreamChatTheme.of(context)
+            .channelTheme
+            .channelHeaderTheme
+            .title
+            .copyWith(
+              fontSize: 16,
+              fontWeight: FontWeight.bold,
+            ),
       );
 
-  Widget _buildConnectingTitleState() {
+  Widget _buildConnectingTitleState(BuildContext context) {
     return Row(
       mainAxisAlignment: MainAxisAlignment.center,
       children: [
@@ -116,37 +155,47 @@ class ChannelListHeader extends StatelessWidget implements PreferredSizeWidget {
         SizedBox(width: 10),
         Text(
           'Searching for Network',
-          style: TextStyle(
-            fontSize: 16,
-            fontWeight: FontWeight.bold,
-            color: Colors.black,
-          ),
-        )
+          style: StreamChatTheme.of(context)
+              .channelTheme
+              .channelHeaderTheme
+              .title
+              .copyWith(
+                fontSize: 16,
+                fontWeight: FontWeight.bold,
+              ),
+        ),
       ],
     );
   }
 
-  Widget _buildDisconnectedTitleState(Client client) {
+  Widget _buildDisconnectedTitleState(BuildContext context, Client client) {
     return Row(
       mainAxisAlignment: MainAxisAlignment.center,
       children: [
         Text(
           'Offline...',
-          style: TextStyle(
-            fontSize: 16,
-            fontWeight: FontWeight.bold,
-            color: Colors.black,
-          ),
+          style: StreamChatTheme.of(context)
+              .channelTheme
+              .channelHeaderTheme
+              .title
+              .copyWith(
+                fontSize: 16,
+                fontWeight: FontWeight.bold,
+              ),
         ),
         TextButton(
           onPressed: () => client.connect(),
           child: Text(
             'Try Again',
-            style: TextStyle(
-              fontSize: 16,
-              fontWeight: FontWeight.bold,
-              color: Color(0xFF006CFF),
-            ),
+            style: StreamChatTheme.of(context)
+                .channelTheme
+                .channelHeaderTheme
+                .title
+                .copyWith(
+                  fontSize: 16,
+                  fontWeight: FontWeight.bold,
+                  color: Color(0xFF006CFF),
+                ),
           ),
         ),
       ],