implemented enlarged emoji rendering for chat messages containing up to three emojis

lib/utils/emoji_detection.dart

@@ -0,0 +1,86 @@
+import 'package:characters/characters.dart';
+
+/// Detects chat messages that consist solely of emoji so the UI can render
+/// them enlarged (à la WhatsApp/iMessage).
+///
+/// Returns the font size to use for such a message, or `null` when [text]
+/// contains any non-emoji, non-whitespace character (i.e. render normally).
+
+const int _zwj = 0x200D;
+const int _vs15 = 0xFE0E;
+const int _vs16 = 0xFE0F;
+const int _keycap = 0x20E3;
+
+/// Codepoints that only ever glue an emoji sequence together and never stand
+/// on their own — they don't disqualify a cluster from counting as emoji.
+bool _isModifier(int r) =>
+    r == _zwj ||
+    r == _vs15 ||
+    r == _vs16 ||
+    r == _keycap ||
+    (r >= 0x1F3FB && r <= 0x1F3FF) || // skin-tone modifiers
+    (r >= 0xE0020 && r <= 0xE007F); // tag characters (flag sequences)
+
+/// The digits, `#` and `*` that become emoji only when combined with the
+/// keycap combining mark.
+bool _isKeycapBase(int r) =>
+    r == 0x23 || r == 0x2A || (r >= 0x30 && r <= 0x39);
+
+bool _isEmojiRune(int r) {
+  // Bulk of modern emoji live in the astral pictograph block: emoticons,
+  // transport, supplemental symbols, extended-A, regional indicators, …
+  if (r >= 0x1F000 && r <= 0x1FAFF) return true;
+  // Scattered BMP emoji ranges (misc symbols, dingbats, arrows, stars, …).
+  if (r >= 0x2600 && r <= 0x27BF) return true;
+  if (r >= 0x2300 && r <= 0x23FF) return true;
+  if (r >= 0x2B00 && r <= 0x2BFF) return true;
+  if (r >= 0x2190 && r <= 0x21FF) return true;
+  if (r >= 0x25A0 && r <= 0x25FF) return true;
+  const singles = {
+    0x00A9, 0x00AE, 0x203C, 0x2049, 0x2122, 0x2139,
+    0x2934, 0x2935, 0x3030, 0x303D, 0x3297, 0x3299, 0x24C2,
+  };
+  return singles.contains(r);
+}
+
+bool _isEmojiCluster(String cluster) {
+  final runes = cluster.runes.toList(growable: false);
+  final hasKeycap = runes.contains(_keycap);
+  var hasEmoji = false;
+  for (final r in runes) {
+    if (_isModifier(r)) continue;
+    if (_isEmojiRune(r)) {
+      hasEmoji = true;
+      continue;
+    }
+    if (hasKeycap && _isKeycapBase(r)) {
+      hasEmoji = true;
+      continue;
+    }
+    return false; // a plain text character → not an emoji cluster
+  }
+  return hasEmoji;
+}
+
+/// Maximum number of emojis a message may contain to still be enlarged; longer
+/// emoji strings would turn into a wall of giant glyphs and render normally.
+const int _maxEnlargedEmojis = 3;
+
+/// Font size for an emoji-only [text] of at most [_maxEnlargedEmojis] emojis.
+/// `null` means the message is not emoji-only (or has too many emojis) and
+/// should render at the normal body size.
+double? standaloneEmojiFontSize(String text) {
+  final trimmed = text.trim();
+  if (trimmed.isEmpty) return null;
+
+  var count = 0;
+  for (final cluster in trimmed.characters) {
+    if (cluster.trim().isEmpty) continue; // whitespace between emojis
+    if (!_isEmojiCluster(cluster)) return null;
+    count++;
+    if (count > _maxEnlargedEmojis) return null;
+  }
+
+  if (count == 0) return null;
+  return 34;
+}

lib/view/pages/talk/data/chat_message.dart

@@ -5,6 +5,7 @@ import '../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../api/marianumcloud/talk/chat/rich_object_string_processor.dart';
 import '../../../../model/account_data.dart';
 import '../../../../model/endpoint_data.dart';
+import '../../../../utils/emoji_detection.dart';
 import '../../../../utils/url_opener.dart';
 import '../widgets/highlighted_linkify.dart';
 
@@ -28,13 +29,29 @@ class ChatMessage {
   }
 
   Widget getWidget({String? highlightQuery, TextStyle? style}) {
-    var contentWidget = HighlightedLinkify(
+    final emojiFontSize = standaloneEmojiFontSize(content);
+    final effectiveStyle = emojiFontSize == null
+        ? style
+        : (style ?? const TextStyle()).copyWith(
+            fontSize: emojiFontSize,
+            height: 1.15,
+          );
+
+    Widget contentWidget = HighlightedLinkify(
       text: content,
       onOpen: UrlOpener.onOpen,
       highlight: highlightQuery,
-      style: style,
+      style: effectiveStyle,
     );
 
+    // Enlarged emoji glyphs otherwise sit flush against the bubble edges.
+    if (emojiFontSize != null) {
+      contentWidget = Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 6),
+        child: contentWidget,
+      );
+    }
+
     if (originalData?['object']?.type == RichObjectStringObjectType.talkPoll) {
       return ListTile(
         leading: const Icon(Icons.poll_outlined),

pubspec.yaml

@@ -21,6 +21,9 @@ dependencies:
   async: ^2.11.0
   badges: ^3.1.2
   cached_network_image: ^3.4.1
+  # Grapheme-cluster iteration for emoji-only message detection
+  # (lib/utils/emoji_detection.dart). Already present transitively via flutter.
+  characters: ^1.4.0
   collection: ^1.19.0
   connectivity_plus: ^7.1.0
   crypto: ^3.0.6

test/utils/emoji_detection_test.dart

@@ -0,0 +1,62 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/utils/emoji_detection.dart';
+
+void main() {
+  group('standaloneEmojiFontSize', () {
+    test('returns null for empty or whitespace-only text', () {
+      expect(standaloneEmojiFontSize(''), isNull);
+      expect(standaloneEmojiFontSize('   '), isNull);
+    });
+
+    test('returns null for plain text', () {
+      expect(standaloneEmojiFontSize('Hallo'), isNull);
+      expect(standaloneEmojiFontSize('ok'), isNull);
+    });
+
+    test('returns null when emoji is mixed with text', () {
+      expect(standaloneEmojiFontSize('Hallo 😀'), isNull);
+      expect(standaloneEmojiFontSize('😀 super'), isNull);
+    });
+
+    test('enlarges a single emoji the most', () {
+      expect(standaloneEmojiFontSize('😀'), 34);
+      expect(standaloneEmojiFontSize('👍'), 34);
+    });
+
+    test('enlarges up to three emojis at the largest size', () {
+      expect(standaloneEmojiFontSize('😀😀😀'), 34);
+      expect(standaloneEmojiFontSize('😀 😀 😀'), 34);
+    });
+
+    test('does not enlarge more than three emojis', () {
+      expect(standaloneEmojiFontSize('😀😀😀😀'), isNull);
+      expect(standaloneEmojiFontSize('😀😀😀😀😀😀'), isNull);
+    });
+
+    test('handles ZWJ sequences as a single emoji', () {
+      // Family emoji: multiple codepoints joined via ZWJ → one cluster.
+      expect(standaloneEmojiFontSize('👨‍👩‍👧‍👦'), 34);
+    });
+
+    test('handles skin-tone modified emoji as a single emoji', () {
+      expect(standaloneEmojiFontSize('👍🏽'), 34);
+    });
+
+    test('handles emoji with variation selectors', () {
+      expect(standaloneEmojiFontSize('❤️'), 34);
+      expect(standaloneEmojiFontSize('⭐'), 34);
+    });
+
+    test('handles keycap emoji', () {
+      expect(standaloneEmojiFontSize('1️⃣'), 34);
+    });
+
+    test('handles flag emoji (regional indicators)', () {
+      expect(standaloneEmojiFontSize('🇩🇪'), 34);
+    });
+
+    test('bare digits without keycap are not emoji', () {
+      expect(standaloneEmojiFontSize('123'), isNull);
+    });
+  });
+}