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lib/pages/epub_reader/mixins/link_handling_mixin.dart

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+part of '../reader_screen.dart';
+
+mixin _LinkHandlingMixin on State<ReaderScreen> {
+  // === Borrowed state (provided by _ReaderScreenState fields) ===
+  BookSession get bookSession;
+
+  ReaderSettings get readerSettings;
+
+  // === Cross-mixin: _SpineNavigationMixin ===
+  Future<void> loadCarousel({
+    String anchor = 'top',
+    int? overrideSpineIndex,
+    double? restoreScrollRatio,
+  });
+
+  // === Cross-mixin: _ThemeMixin ===
+  EpubTheme getEpubTheme();
+
+  bool shouldHandleLinkTap(String url) {
+    if (url.startsWith('epub://')) {
+      final index = bookSession.findSpineIndexByUrl(url);
+      return index != null;
+    } else {
+      return readerSettings.linkHandling != ReaderLinkHandling.never;
+    }
+  }
+
+  Future<void> handleLinkTap(String url) async {
+    if (url.startsWith('epub://')) {
+      final index = bookSession.findSpineIndexByUrl(url);
+      if (index != null) {
+        String anchor = 'top';
+        if (url.contains('#')) {
+          anchor = url.split('#').last;
+        }
+        await loadCarousel(anchor: anchor, overrideSpineIndex: index);
+      }
+    } else {
+      final linkHandling = readerSettings.linkHandling;
+      final uri = Uri.tryParse(url);
+
+      if (uri != null && await canLaunchUrl(uri)) {
+        if (linkHandling == ReaderLinkHandling.always) {
+          await launchUrl(uri);
+        } else if (linkHandling == ReaderLinkHandling.ask) {
+          if (mounted && context.mounted) {
+            final shouldOpen =
+                await showDialog<bool>(
+                  context: context,
+                  builder: (context) => AlertDialog(
+                    title: const Text('打开外部链接'),
+                    content: Text('是否打开链接: $url'),
+                    actions: [
+                      TextButton(
+                        onPressed: () => Navigator.of(context).pop(false),
+                        child: const Text('取消'),
+                      ),
+                      FilledButton(
+                        onPressed: () => Navigator.of(context).pop(true),
+                        child: const Text('打开'),
+                      ),
+                    ],
+                  ),
+                ) ??
+                false;
+
+            if (shouldOpen) {
+              await launchUrl(uri);
+            }
+          }
+        }
+        // ReaderLinkHandling.never: do nothing
+      } else {
+        if (mounted && context.mounted) {
+          ScaffoldMessenger.of(context).showSnackBar(
+            SnackBar(content: Text('无法打开链接: $url')),
+          );
+        }
+      }
+    }
+  }
+}