Add topic-list page

assets/l10n/app_en.arb

@@ -84,6 +84,10 @@
   "@actionSheetOptionMarkChannelAsRead": {
     "description": "Label for marking a channel as read."
   },
+  "actionSheetOptionListOfTopics": "List of topics",
+  "@actionSheetOptionListOfTopics": {
+    "description": "Label for navigating to a channel's topic-list page."
+  },
   "actionSheetOptionMuteTopic": "Mute topic",
   "@actionSheetOptionMuteTopic":  {
     "description": "Label for muting a topic on action sheet."
@@ -713,6 +717,10 @@
   "@mainMenuMyProfile": {
     "description": "Label for main-menu button leading to the user's own profile."
   },
+  "topicsButtonLabel": "TOPICS",
+  "@topicsButtonLabel": {
+    "description": "Label for message list button leading to topic-list page. (Use ALL CAPS for cased alphabets: Latin, Greek, Cyrillic, etc.)"
+  },
   "channelFeedButtonTooltip": "Channel feed",
   "@channelFeedButtonTooltip": {
     "description": "Tooltip for button to navigate to a given channel's feed"

lib/generated/l10n/zulip_localizations.dart

@@ -236,6 +236,12 @@ abstract class ZulipLocalizations {
   /// **'Mark channel as read'**
   String get actionSheetOptionMarkChannelAsRead;
 
+  /// Label for navigating to a channel's topic-list page.
+  ///
+  /// In en, this message translates to:
+  /// **'List of topics'**
+  String get actionSheetOptionListOfTopics;
+
   /// Label for muting a topic on action sheet.
   ///
   /// In en, this message translates to:
@@ -1064,6 +1070,12 @@ abstract class ZulipLocalizations {
   /// **'My profile'**
   String get mainMenuMyProfile;
 
+  /// Label for message list button leading to topic-list page. (Use ALL CAPS for cased alphabets: Latin, Greek, Cyrillic, etc.)
+  ///
+  /// In en, this message translates to:
+  /// **'TOPICS'**
+  String get topicsButtonLabel;
+
   /// Tooltip for button to navigate to a given channel's feed
   ///
   /// In en, this message translates to:

lib/generated/l10n/zulip_localizations_ar.dart

@@ -76,6 +76,9 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get actionSheetOptionMarkChannelAsRead => 'Mark channel as read';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Mute topic';
 
@@ -584,6 +587,9 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'My profile';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Channel feed';
 

lib/generated/l10n/zulip_localizations_en.dart

@@ -76,6 +76,9 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get actionSheetOptionMarkChannelAsRead => 'Mark channel as read';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Mute topic';
 
@@ -584,6 +587,9 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'My profile';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Channel feed';
 

lib/generated/l10n/zulip_localizations_ja.dart

@@ -76,6 +76,9 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get actionSheetOptionMarkChannelAsRead => 'Mark channel as read';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Mute topic';
 
@@ -584,6 +587,9 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'My profile';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Channel feed';
 

lib/generated/l10n/zulip_localizations_nb.dart

@@ -76,6 +76,9 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get actionSheetOptionMarkChannelAsRead => 'Mark channel as read';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Mute topic';
 
@@ -584,6 +587,9 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'My profile';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Channel feed';
 

lib/generated/l10n/zulip_localizations_pl.dart

@@ -78,6 +78,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get actionSheetOptionMarkChannelAsRead =>
       'Oznacz kanał jako przeczytany';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Wycisz wątek';
 
@@ -593,6 +596,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'Mój profil';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Strumień kanału';
 

lib/generated/l10n/zulip_localizations_ru.dart

@@ -78,6 +78,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   String get actionSheetOptionMarkChannelAsRead =>
       'Отметить канал как прочитанный';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Отключить тему';
 
@@ -597,6 +600,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'Мой профиль';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Лента канала';
 

lib/generated/l10n/zulip_localizations_sk.dart

@@ -76,6 +76,9 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get actionSheetOptionMarkChannelAsRead => 'Mark channel as read';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Stlmiť tému';
 
@@ -586,6 +589,9 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'Môj profil';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Channel feed';
 

lib/generated/l10n/zulip_localizations_uk.dart

@@ -79,6 +79,9 @@ class ZulipLocalizationsUk extends ZulipLocalizations {
   String get actionSheetOptionMarkChannelAsRead =>
       'Позначити канал як прочитаний';
 
+  @override
+  String get actionSheetOptionListOfTopics => 'List of topics';
+
   @override
   String get actionSheetOptionMuteTopic => 'Заглушити тему';
 
@@ -596,6 +599,9 @@ class ZulipLocalizationsUk extends ZulipLocalizations {
   @override
   String get mainMenuMyProfile => 'Мій профіль';
 
+  @override
+  String get topicsButtonLabel => 'TOPICS';
+
   @override
   String get channelFeedButtonTooltip => 'Стрічка каналу';
 

lib/widgets/action_sheet.dart

@@ -28,6 +28,7 @@ import 'page.dart';
 import 'store.dart';
 import 'text.dart';
 import 'theme.dart';
+import 'topic_list.dart';
 
 void _showActionSheet(
   BuildContext context, {
@@ -174,24 +175,43 @@ void showChannelActionSheet(BuildContext context, {
   final pageContext = PageRoot.contextOf(context);
   final store = PerAccountStoreWidget.of(pageContext);
 
-  final optionButtons = <ActionSheetMenuItemButton>[];
+  final optionButtons = <ActionSheetMenuItemButton>[
+    TopicListButton(pageContext: pageContext, channelId: channelId),
+  ];
+
   final unreadCount = store.unreads.countInChannelNarrow(channelId);
   if (unreadCount > 0) {
     optionButtons.add(
       MarkChannelAsReadButton(pageContext: pageContext, channelId: channelId));
   }
-  if (optionButtons.isEmpty) {
-    // TODO(a11y): This case makes a no-op gesture handler; as a consequence,
-    //   we're presenting some UI (to people who use screen-reader software) as
-    //   though it offers a gesture interaction that it doesn't meaningfully
-    //   offer, which is confusing. The solution here is probably to remove this
-    //   is-empty case by having at least one button that's always present,
-    //   such as "copy link to channel".
-    return;
-  }
+
   _showActionSheet(pageContext, optionButtons: optionButtons);
 }
 
+class TopicListButton extends ActionSheetMenuItemButton {
+  const TopicListButton({
+    super.key,
+    required this.channelId,
+    required super.pageContext,
+  });
+
+  final int channelId;
+
+  @override
+  IconData get icon => ZulipIcons.topics;
+
+  @override
+  String label(ZulipLocalizations zulipLocalizations) {
+    return zulipLocalizations.actionSheetOptionListOfTopics;
+  }
+
+  @override
+  void onPressed() {
+    Navigator.push(pageContext,
+      TopicListPage.buildRoute(context: pageContext, streamId: channelId));
+  }
+}
+
 class MarkChannelAsReadButton extends ActionSheetMenuItemButton {
   const MarkChannelAsReadButton({
     super.key,

lib/widgets/content.dart

@@ -26,6 +26,7 @@ import 'poll.dart';
 import 'scrolling.dart';
 import 'store.dart';
 import 'text.dart';
+import 'theme.dart';
 
 /// A central place for styles for Zulip content (rendered Zulip Markdown).
 ///
@@ -988,7 +989,7 @@ class WebsitePreview extends StatelessWidget {
         // TODO(#488) use different color for non-message contexts
         // TODO(#647) use different color for highlighted messages
         // TODO(#681) use different color for DM messages
-        color: MessageListTheme.of(context).bgMessageRegular,
+        color: DesignVariables.of(context).bgMessageRegular,
         child: ClipRect(
           child: ConstrainedBox(
             constraints: BoxConstraints(maxHeight: 80),

lib/widgets/icons.dart

@@ -144,11 +144,14 @@ abstract final class ZulipIcons {
   /// The Zulip custom icon "topic".
   static const IconData topic = IconData(0xf128, fontFamily: "Zulip Icons");
 
+  /// The Zulip custom icon "topics".
+  static const IconData topics = IconData(0xf129, fontFamily: "Zulip Icons");
+
   /// The Zulip custom icon "unmute".
-  static const IconData unmute = IconData(0xf129, fontFamily: "Zulip Icons");
+  static const IconData unmute = IconData(0xf12a, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "user".
-  static const IconData user = IconData(0xf12a, fontFamily: "Zulip Icons");
+  static const IconData user = IconData(0xf12b, fontFamily: "Zulip Icons");
 
   // END GENERATED ICON DATA
 }