viewer: keyboard shortcuts for navigation

lib/widgets/common/action_mixins/feedback.dart

@@ -84,7 +84,7 @@ mixin FeedbackMixin {
         itemCount: itemCount,
         onCancel: onCancel,
         onDone: (processed) {
-          Navigator.of(context).pop();
+          Navigator.pop(context);
           onDone?.call(processed);
         },
       ),

lib/widgets/viewer/entry_vertical_pager.dart

@@ -11,6 +11,7 @@ import 'package:aves/widgets/viewer/entry_horizontal_pager.dart';
 import 'package:aves/widgets/viewer/info/info_page.dart';
 import 'package:aves/widgets/viewer/info/notifications.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:screen_brightness/screen_brightness.dart';
 
 class ViewerVerticalPageView extends StatefulWidget {
@@ -93,18 +94,7 @@ class _ViewerVerticalPageViewState extends State<ViewerVerticalPageView> {
     // fake page for opacity transition between collection and viewer
     const transitionPage = SizedBox();
 
-    final imagePage = hasCollection
+    final imagePage = _buildImagePage();
-        ? MultiEntryScroller(
-            collection: collection!,
-            pageController: widget.horizontalPager,
-            onPageChanged: widget.onHorizontalPageChanged,
-            onViewDisposed: widget.onViewDisposed,
-          )
-        : entry != null
-            ? SingleEntryScroller(
-                entry: entry!,
-              )
-            : const SizedBox();
 
     final infoPage = NotificationListener<ShowImageNotification>(
       onNotification: (notification) {
@@ -150,6 +140,58 @@ class _ViewerVerticalPageViewState extends State<ViewerVerticalPageView> {
     );
   }
 
+  Widget _buildImagePage() {
+    Widget? child;
+    Map<ShortcutActivator, Intent>? shortcuts;
+
+    if (hasCollection) {
+      child = MultiEntryScroller(
+        collection: collection!,
+        pageController: widget.horizontalPager,
+        onPageChanged: widget.onHorizontalPageChanged,
+        onViewDisposed: widget.onViewDisposed,
+      );
+      shortcuts = const {
+        SingleActivator(LogicalKeyboardKey.arrowLeft): ShowPreviousIntent(),
+        SingleActivator(LogicalKeyboardKey.arrowRight): ShowNextIntent(),
+        SingleActivator(LogicalKeyboardKey.arrowUp): LeaveIntent(),
+        SingleActivator(LogicalKeyboardKey.arrowDown): ShowInfoIntent(),
+      };
+    } else if (entry != null) {
+      child = SingleEntryScroller(
+        entry: entry!,
+      );
+      shortcuts = const {
+        SingleActivator(LogicalKeyboardKey.arrowUp): LeaveIntent(),
+        SingleActivator(LogicalKeyboardKey.arrowDown): ShowInfoIntent(),
+      };
+    }
+    if (child != null) {
+      return FocusableActionDetector(
+        autofocus: true,
+        shortcuts: shortcuts,
+        actions: {
+          ShowPreviousIntent: CallbackAction<Intent>(onInvoke: (intent) => _jumpHorizontalPage(-1)),
+          ShowNextIntent: CallbackAction<Intent>(onInvoke: (intent) => _jumpHorizontalPage(1)),
+          LeaveIntent: CallbackAction<Intent>(onInvoke: (intent) => Navigator.pop(context)),
+          ShowInfoIntent: CallbackAction<Intent>(onInvoke: (intent) => ShowInfoNotification().dispatch(context)),
+        },
+        child: child,
+      );
+    }
+    return const SizedBox();
+  }
+
+  void _jumpHorizontalPage(int delta) {
+    final pageController = widget.horizontalPager;
+    final page = pageController.page?.round();
+    final _collection = collection;
+    if (page != null && _collection != null) {
+      final target = (page + delta).clamp(0, _collection.entryCount - 1);
+      pageController.jumpToPage(target);
+    }
+  }
+
   void _onVerticalPageControllerChanged() {
     final page = widget.verticalPager.page!;
 
@@ -205,3 +247,21 @@ class _ViewerVerticalPageViewState extends State<ViewerVerticalPageView> {
     }
   }
 }
+
+// keyboard shortcut intents
+
+class ShowPreviousIntent extends Intent {
+  const ShowPreviousIntent();
+}
+
+class ShowNextIntent extends Intent {
+  const ShowNextIntent();
+}
+
+class LeaveIntent extends Intent {
+  const LeaveIntent();
+}
+
+class ShowInfoIntent extends Intent {
+  const ShowInfoIntent();
+}

lib/widgets/viewer/entry_viewer_stack.dart

@@ -198,12 +198,15 @@ class _EntryViewerStackState extends State<EntryViewerStack> with FeedbackMixin,
               _goToCollection(notification.filter);
             } else if (notification is EntryRemovedNotification) {
               _onEntryRemoved(context, notification.entry);
-            }
+            } else if (notification is ToggleOverlayNotification) {
-            return false;
-          },
-          child: NotificationListener<ToggleOverlayNotification>(
-            onNotification: (notification) {
               _overlayVisible.value = notification.visible ?? !_overlayVisible.value;
+            } else if (notification is ShowInfoNotification) {
+              // remove focus, if any, to prevent viewer shortcuts activation from the Info page
+              FocusManager.instance.primaryFocus?.unfocus();
+              _goToVerticalPage(infoPage);
+            } else {
+              return false;
+            }
             return true;
           },
           child: Stack(
@@ -226,7 +229,6 @@ class _EntryViewerStackState extends State<EntryViewerStack> with FeedbackMixin,
           ),
         ),
       ),
-      ),
     );
   }
 
@@ -249,18 +251,12 @@ class _EntryViewerStackState extends State<EntryViewerStack> with FeedbackMixin,
           );
         }
 
-        return NotificationListener<ShowInfoNotification>(
+        return mainEntry.isMultiPage
-          onNotification: (notification) {
-            _goToVerticalPage(infoPage);
-            return true;
-          },
-          child: mainEntry.isMultiPage
             ? PageEntryBuilder(
                 multiPageController: context.read<MultiPageConductor>().getController(mainEntry),
                 builder: (pageEntry) => _buildContent(pageEntry: pageEntry),
               )
-              : _buildContent(),
+            : _buildContent();
-        );
       },
     );