feat: add quotations from marked text, with citations and sharing

app/lib/presentation/app.dart

@@ -36,6 +36,7 @@ class AppDependencies {
     Strings? strings,
     KeyStore? keys,
     Future<PickedPem?> Function(String title)? pickPemFile,
+    Future<void> Function(String text)? share,
   })  : db = database ?? MewsDatabase(),
         fetch = fetch ?? Actor.create(FetchHandler.new),
         strings = strings ?? Strings() {
@@ -61,6 +62,7 @@ class AppDependencies {
       keys: this.keys,
       strings: this.strings,
       pickPemFile: pickPemFile,
+      share: share,
     );
     browser = BrowserController(
       db: db,

app/lib/presentation/reader/mews_page_view.dart

@@ -36,6 +36,7 @@ class MewsPageView extends StatefulWidget {
     this.onFormChange,
     this.fetchImageBytes,
     this.scrollController,
+    this.onSaveQuotation,
     this.ownPage = false,
     super.key,
   });
@@ -57,6 +58,10 @@ class MewsPageView extends StatefulWidget {
   final Future<Uint8List?> Function(String url)? fetchImageBytes;
   final ScrollController? scrollController;
 
+  /// Called with text the reader marked and chose to keep as a quotation.
+  /// Null on a view that cannot keep one, such as a swipe peek.
+  final void Function(String text)? onSaveQuotation;
+
   /// Whether this is one of the client's own pages. Those are built from the
   /// same blocks, but they are interface rather than an article, so they are
   /// laid out denser and wider, rows are divided instead of bulleted, and
@@ -171,8 +176,14 @@ class _MewsPageViewState extends State<MewsPageView> {
           textDirection: widget.page.direction == TextDirection.rtl
               ? ui.TextDirection.rtl
               : ui.TextDirection.ltr,
-          // Page text is the reader's to copy; forms manage their own selection.
+          // Page text is the reader's to copy and to keep; forms manage
+          // their own selection. The toolbar offers to keep the marked
+          // text as a quotation, so the selection's text is carried here.
           child: SelectionArea(
+            onSelectionChanged: (content) =>
+                _markedText = content?.plainText,
+            contextMenuBuilder: (context, selectableRegion) =>
+                _selectionToolbar(context, selectableRegion),
             child: ColoredBox(
               color: palette.background,
               child: ListView(
@@ -201,6 +212,36 @@ class _MewsPageViewState extends State<MewsPageView> {
     );
   }
 
+  /// The text of the selection now on the page, if any, so the toolbar can
+  /// offer to keep it.
+  String? _markedText;
+
+  /// The selection toolbar: the platform's own buttons, plus the choice to
+  /// keep the marked text as a quotation when a place to keep it is given.
+  Widget _selectionToolbar(
+      BuildContext context, SelectableRegionState selectableRegion) {
+    final items = selectableRegion.contextMenuButtonItems;
+    final marked = _markedText?.trim();
+    if (widget.onSaveQuotation != null && marked != null && marked.isNotEmpty) {
+      items.insert(
+        0,
+        ContextMenuButtonItem(
+          type: ContextMenuButtonType.custom,
+          label: StringsScope.of(context).t('quotations-save'),
+          onPressed: () {
+            widget.onSaveQuotation!(marked);
+            selectableRegion.hideToolbar();
+            selectableRegion.clearSelection();
+          },
+        ),
+      );
+    }
+    return AdaptiveTextSelectionToolbar.buttonItems(
+      anchors: selectableRegion.contextMenuAnchors,
+      buttonItems: items,
+    );
+  }
+
   Widget _notice(String text, double base, MewsPalette palette) => Padding(
     padding: EdgeInsets.only(bottom: base),
     child: Text(

app/lib/presentation/reader/reader_screen.dart

@@ -336,6 +336,14 @@ class _ReaderScreenState extends State<ReaderScreen> {
         },
         onFormChange: (form, values) =>
             deps.browser.narrowWhileTyping(form.action, values),
+        // The reader's marked text is kept with the page it came from, so
+        // its citation can name the author when the page did.
+        onSaveQuotation: (text) => deps.db.addQuotation(
+              quote: text,
+              pageUrl: page.url,
+              pageTitle: page.title,
+              author: page.author,
+            ),
         fetchImageBytes: deps.browser.fetchImageBytes,
         scrollController: _scroll,
       );