feat(ui): add the ability to add a background image in MessageListView

packages/stream_chat_flutter/CHANGELOG.md

@@ -34,6 +34,10 @@
 
 - `UserListView` `filter` property now is non-nullable.
 
+✅ Added
+
+- `MessageListViewThemeData` now accepts a `DecorationImage` as a background image for `MessageListView`.
+
 🐞 Fixed
 
 - [[#668]](https://github.com/GetStream/stream-chat-flutter/issues/668): Fix `MessageInput` rendering errors in case

packages/stream_chat_flutter/example/lib/tutorial_part_6.dart

@@ -63,6 +63,12 @@ class MyApp extends StatelessWidget {
           borderRadius: BorderRadius.circular(8),
         ),
       ),
+      messageListViewTheme: const MessageListViewThemeData(
+          backgroundColor: Colors.grey,
+          backgroundImage: DecorationImage(
+            image: AssetImage('assets/background_doodle.png'),
+            fit: BoxFit.cover,
+          )),
       otherMessageTheme: MessageThemeData(
         messageBackgroundColor: colorTheme.textHighEmphasis,
         messageTextStyle: TextStyle(

packages/stream_chat_flutter/example/pubspec.yaml

@@ -47,8 +47,8 @@ flutter:
   uses-material-design: true
 
   # To add assets to your application, add an assets section, like this:
-  # assets:
-  #   - images/a_dot_burr.jpeg
+  assets:
+    - assets/background_doodle.png
   #   - images/a_dot_ham.jpeg
 
   # An image asset can refer to one or more resolution-specific "variants", see

packages/stream_chat_flutter/lib/src/message_list_view.dart

@@ -638,10 +638,14 @@ class _MessageListViewState extends State<MessageListView> {
     );
 
     final backgroundColor = MessageListViewTheme.of(context).backgroundColor;
+    final backgroundImage = MessageListViewTheme.of(context).backgroundImage;
 
-    if (backgroundColor != null) {
-      return ColoredBox(
-        color: backgroundColor,
+    if (backgroundColor != null || backgroundImage != null) {
+      return Container(
+        decoration: BoxDecoration(
+          color: backgroundColor,
+          image: backgroundImage,
+        ),
         child: child,
       );
     }

packages/stream_chat_flutter/lib/src/theme/message_list_view_theme.dart

@@ -60,17 +60,23 @@ class MessageListViewThemeData with Diagnosticable {
   /// Creates a [MessageListViewThemeData].
   const MessageListViewThemeData({
     this.backgroundColor,
+    this.backgroundImage,
   });
 
   /// The color of the [MessageListView] background.
   final Color? backgroundColor;
 
+  /// The image of the [MessageListView] background.
+  final DecorationImage? backgroundImage;
+
   /// Copies this [MessageListViewThemeData] to another.
   MessageListViewThemeData copyWith({
     Color? backgroundColor,
+    DecorationImage? backgroundImage,
   }) =>
       MessageListViewThemeData(
         backgroundColor: backgroundColor ?? this.backgroundColor,
+        backgroundImage: backgroundImage ?? this.backgroundImage,
       );
 
   /// Linearly interpolate between two [MessageListView] themes.
@@ -83,6 +89,7 @@ class MessageListViewThemeData with Diagnosticable {
   ) =>
       MessageListViewThemeData(
         backgroundColor: Color.lerp(a.backgroundColor, b.backgroundColor, t),
+        backgroundImage: t < 0.5 ? a.backgroundImage : b.backgroundImage,
       );
 
   /// Merges one [MessageListViewThemeData] with another.
@@ -90,6 +97,7 @@ class MessageListViewThemeData with Diagnosticable {
     if (other == null) return this;
     return copyWith(
       backgroundColor: other.backgroundColor,
+      backgroundImage: other.backgroundImage,
     );
   }
 
@@ -98,14 +106,20 @@ class MessageListViewThemeData with Diagnosticable {
       identical(this, other) ||
       other is MessageListViewThemeData &&
           runtimeType == other.runtimeType &&
-          backgroundColor == other.backgroundColor;
+          backgroundColor == other.backgroundColor &&
+          backgroundImage == other.backgroundImage;
 
   @override
-  int get hashCode => backgroundColor.hashCode;
+  int get hashCode => backgroundColor.hashCode + backgroundImage.hashCode;
 
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.add(ColorProperty('backgroundColor', backgroundColor));
+    properties
+      ..add(ColorProperty('backgroundColor', backgroundColor))
+      ..add(
+        DiagnosticsProperty<DecorationImage>('backgroundImage', backgroundImage,
+            defaultValue: null),
+      );
   }
 }

packages/stream_chat_flutter/test/src/message_list_view_test.dart

@@ -1,4 +1,8 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter/stream_chat_flutter.dart';
@@ -20,7 +24,8 @@ void main() {
         .thenAnswer((_) => const Stream.empty());
     when(() => channelClientState.messagesStream)
         .thenAnswer((_) => const Stream.empty());
-    when(() => channelClientState.messages).thenReturn([]);
+    when(() => channelClientState.messages)
+        .thenReturn([Message(text: 'Hello World!')]);
     when(() => channelClientState.isUpToDate).thenReturn(true);
   });
 
@@ -46,4 +51,52 @@ void main() {
     expect(find.byType(MessageListView), findsOneWidget);
     expect(find.byKey(emptyWidgetKey), findsOneWidget);
   });
+
+  testWidgets('renders empty message list view with custom background',
+      (tester) async {
+    const emptyWidgetKey = Key('empty_widget');
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: DefaultAssetBundle(
+          bundle: _TestAssetBundle(),
+          child: StreamChat(
+            client: client,
+            streamChatThemeData: StreamChatThemeData.light().copyWith(
+                messageListViewTheme: const MessageListViewThemeData(
+                    backgroundColor: Colors.grey,
+                    backgroundImage: DecorationImage(
+                      image: AssetImage('assets/background.png'),
+                      fit: BoxFit.cover,
+                    ))),
+            child: StreamChannel(
+              channel: channel,
+              child: MessageListView(
+                emptyBuilder: (_) => Container(key: emptyWidgetKey),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    expect(find.byType(MessageListView), findsOneWidget);
+    expect(find.byKey(emptyWidgetKey), findsOneWidget);
+    expect(find.byType(DecorationImage, skipOffstage: false), findsOneWidget);
+  });
+}
+
+class _TestAssetBundle extends CachingAssetBundle {
+  @override
+  Future<ByteData> load(String key) async {
+    if (key == 'assets/background.png') {
+      return ByteData.view(
+        Uint8List.fromList(
+          utf8.encode('Background'),
+        ).buffer,
+      );
+    }
+    return ByteData(0);
+  }
 }

packages/stream_chat_flutter/test/src/theme/message_list_view_theme_test.dart

@@ -109,6 +109,37 @@ void main() {
     expect(messageListViewTheme.backgroundColor,
         _messageListViewThemeDataControlDark.backgroundColor);
   });
+
+  testWidgets(
+      'Pass backgroundImage to MessageListViewThemeData return backgroundImage',
+      (WidgetTester tester) async {
+    late BuildContext _context;
+    await tester.pumpWidget(
+      MaterialApp(
+        builder: (context, child) => StreamChat(
+          client: MockStreamChatClient(),
+          streamChatThemeData: StreamChatThemeData.light()
+              .copyWith(messageListViewTheme: _messageListViewThemeDataImage),
+          child: child,
+        ),
+        home: Builder(
+          builder: (BuildContext context) {
+            _context = context;
+            return Scaffold(
+              body: StreamChannel(
+                channel: MockChannel(),
+                child: const MessageListView(),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+
+    final messageListViewTheme = MessageListViewTheme.of(_context);
+    expect(messageListViewTheme.backgroundImage,
+        _messageListViewThemeDataImage.backgroundImage);
+  });
 }
 
 final _messageListViewThemeDataControl = MessageListViewThemeData(
@@ -122,3 +153,10 @@ const _messageListViewThemeDataControlHalfLerp = MessageListViewThemeData(
 final _messageListViewThemeDataControlDark = MessageListViewThemeData(
   backgroundColor: ColorTheme.dark().barsBg,
 );
+
+const _messageListViewThemeDataImage = MessageListViewThemeData(
+  backgroundImage: DecorationImage(
+    image: AssetImage('example/assets/background_doodle.png'),
+    fit: BoxFit.cover,
+  ),
+);