center back button extracting the widget

example/pubspec.yaml

@@ -1,7 +1,7 @@
 name: example
 description: A new Flutter project.
 
-version: 1.0.8+9
+version: 1.0.10+11
 
 environment:
   sdk: ">=2.2.2 <3.0.0"

lib/src/back_button.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+
+class StreamBackButton extends StatelessWidget {
+  const StreamBackButton({
+    Key key,
+    this.onPressed,
+    this.icon = Icons.arrow_back_ios_outlined,
+  }) : super(key: key);
+
+  final VoidCallback onPressed;
+  final IconData icon;
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(14.0),
+      child: RawMaterialButton(
+        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(4)),
+        elevation: 0,
+        highlightElevation: 0,
+        focusElevation: 0,
+        disabledElevation: 0,
+        hoverElevation: 0,
+        onPressed: () {
+          if (onPressed != null) {
+            onPressed();
+          } else {
+            Navigator.of(context).pop();
+          }
+        },
+        fillColor: Theme.of(context).brightness == Brightness.dark
+            ? Colors.white.withOpacity(.1)
+            : Colors.black.withOpacity(.1),
+        child: Icon(
+          icon ?? Icons.arrow_back_ios_outlined,
+          size: 15,
+          color: Theme.of(context).brightness == Brightness.dark
+              ? Colors.white
+              : Colors.black,
+        ),
+      ),
+    );
+  }
+}

lib/src/channel_header.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:jiffy/jiffy.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter/src/back_button.dart';
 import 'package:stream_chat_flutter/src/channel_name.dart';
 import 'package:stream_chat_flutter/src/stream_chat_theme.dart';
 
@@ -78,7 +79,9 @@ class ChannelHeader extends StatelessWidget implements PreferredSizeWidget {
     final channel = StreamChannel.of(context).channel;
     return AppBar(
       elevation: 1,
-      leading: showBackButton ? _buildBackButton(context) : Container(),
+      leading: showBackButton
+          ? StreamBackButton(onPressed: onBackPressed)
+          : SizedBox(),
       backgroundColor:
           StreamChatTheme.of(context).channelTheme.channelHeaderTheme.color,
       actions: <Widget>[
@@ -135,38 +138,6 @@ class ChannelHeader extends StatelessWidget implements PreferredSizeWidget {
     );
   }
 
-  Padding _buildBackButton(BuildContext context) {
-    return Padding(
-      padding: const EdgeInsets.all(14.0),
-      child: RawMaterialButton(
-        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(4)),
-        elevation: 0,
-        highlightElevation: 0,
-        focusElevation: 0,
-        disabledElevation: 0,
-        hoverElevation: 0,
-        onPressed: () {
-          if (onBackPressed != null) {
-            onBackPressed();
-          } else {
-            Navigator.of(context).pop();
-          }
-        },
-        fillColor: Theme.of(context).brightness == Brightness.dark
-            ? Colors.white.withOpacity(.1)
-            : Colors.black.withOpacity(.1),
-        padding: EdgeInsets.all(4),
-        child: Icon(
-          Icons.arrow_back_ios,
-          size: 15,
-          color: Theme.of(context).brightness == Brightness.dark
-              ? Colors.white
-              : Colors.black,
-        ),
-      ),
-    );
-  }
-
   @override
   final Size preferredSize;
 }

lib/src/thread_header.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter/src/back_button.dart';
 import 'package:stream_chat_flutter/src/stream_chat_theme.dart';
 
 /// ![screenshot](https://raw.githubusercontent.com/GetStream/stream-chat-flutter/master/screenshots/thread_header.png)
@@ -80,7 +81,12 @@ class ThreadHeader extends StatelessWidget implements PreferredSizeWidget {
           StreamChatTheme.of(context).channelTheme.channelHeaderTheme.color,
       actions: <Widget>[
         Container(
-          child: showBackButton ? _buildBackButton(context) : Container(),
+          child: showBackButton
+              ? StreamBackButton(
+                  onPressed: onBackPressed,
+                  icon: Icons.close,
+                )
+              : SizedBox(),
         ),
       ],
       centerTitle: false,
@@ -104,38 +110,6 @@ class ThreadHeader extends StatelessWidget implements PreferredSizeWidget {
     );
   }
 
-  Padding _buildBackButton(BuildContext context) {
-    return Padding(
-      padding: const EdgeInsets.all(14.0),
-      child: AspectRatio(
-        aspectRatio: 1,
-        child: RawMaterialButton(
-          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(4)),
-          elevation: 0,
-          highlightElevation: 0,
-          focusElevation: 0,
-          disabledElevation: 0,
-          hoverElevation: 0,
-          onPressed: () {
-            if (onBackPressed != null) {
-              onBackPressed();
-            } else {
-              Navigator.of(context).pop();
-            }
-          },
-          fillColor: Theme.of(context).brightness == Brightness.dark
-              ? Colors.white.withOpacity(.1)
-              : Colors.black.withOpacity(.1),
-          padding: EdgeInsets.all(4),
-          child: Icon(
-            Icons.close,
-            size: 15,
-          ),
-        ),
-      ),
-    );
-  }
-
   @override
   final Size preferredSize;
 }

lib/stream_chat_flutter.dart

@@ -1,5 +1,6 @@
 export 'package:stream_chat/stream_chat.dart';
 
+export 'src/back_button.dart';
 export 'src/channel_header.dart';
 export 'src/channel_image.dart';
 export 'src/channel_list_view.dart';