[Android] Turn page by volume keys

lib/foundation/appdata.dart

@@ -117,6 +117,7 @@ class _Settings with ChangeNotifier {
     'webdav': [], // empty means not configured
     'dataVersion': 0,
     'quickFavorite': null,
+    'enableTurnPageByVolumeKey': true,
   };
 
   operator [](String key) {

lib/pages/reader/reader.dart

@@ -23,6 +23,7 @@ import 'package:venera/pages/settings/settings_page.dart';
 import 'package:venera/utils/file_type.dart';
 import 'package:venera/utils/io.dart';
 import 'package:venera/utils/translations.dart';
+import 'package:venera/utils/volume.dart';
 import 'package:window_manager/window_manager.dart';
 
 part 'scaffold.dart';
@@ -97,6 +98,8 @@ class _ReaderState extends State<Reader> with _ReaderLocation, _ReaderWindow {
 
   var focusNode = FocusNode();
 
+  VolumeListener? volumeListener;
+
   @override
   void initState() {
     page = widget.initialPage ?? 1;
@@ -107,6 +110,9 @@ class _ReaderState extends State<Reader> with _ReaderLocation, _ReaderWindow {
       updateHistory();
     });
     SystemChrome.setEnabledSystemUIMode(SystemUiMode.immersive);
+    if(appdata.settings['enableTurnPageByVolumeKey']) {
+      handleVolumeEvent();
+    }
     super.initState();
   }
 
@@ -115,6 +121,7 @@ class _ReaderState extends State<Reader> with _ReaderLocation, _ReaderWindow {
     autoPageTurningTimer?.cancel();
     focusNode.dispose();
     SystemChrome.setEnabledSystemUIMode(SystemUiMode.edgeToEdge);
+    stopVolumeEvent();
     super.dispose();
   }
 
@@ -152,6 +159,31 @@ class _ReaderState extends State<Reader> with _ReaderLocation, _ReaderWindow {
       HistoryManager().addHistory(history!);
     }
   }
+
+  void handleVolumeEvent() {
+    if(!App.isAndroid) {
+      // Currently only support Android
+      return;
+    }
+    if(volumeListener != null) {
+      volumeListener?.cancel();
+    }
+    volumeListener = VolumeListener(
+      onDown: () {
+        toNextPage();
+      },
+      onUp: () {
+        toPrevPage();
+      },
+    )..listen();
+  }
+
+  void stopVolumeEvent() {
+    if(volumeListener != null) {
+      volumeListener?.cancel();
+      volumeListener = null;
+    }
+  }
 }
 
 abstract mixin class _ReaderLocation {

lib/pages/reader/scaffold.dart

@@ -470,6 +470,13 @@ class _ReaderScaffoldState extends State<_ReaderScaffold> {
             context.reader.mode = ReaderMode.fromKey(appdata.settings[key]);
             App.rootContext.pop();
           }
+          if (key == "enableTurnPageByVolumeKey") {
+            if(appdata.settings[key]) {
+              context.reader.handleVolumeEvent();
+            } else {
+              context.reader.stopVolumeEvent();
+            }
+          }
           context.reader.update();
         },
       ),

lib/pages/settings/reader.dart

@@ -69,6 +69,14 @@ class _ReaderSettingsState extends State<ReaderSettings> {
             widget.onChanged?.call('limitImageWidth');
           },
         ).toSliver(),
+        if(App.isAndroid)
+          _SwitchSetting(
+            title: 'Turn page by volume key'.tl,
+            settingKey: 'enableTurnPageByVolumeKey',
+            onChanged: () {
+              widget.onChanged?.call('enableTurnPageByVolumeKey');
+            },
+          ).toSliver(),
       ],
     );
   }

lib/utils/volume.dart

@@ -0,0 +1,31 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+
+class VolumeListener {
+  static const channel = EventChannel('venera/volume');
+
+  void Function()? onUp;
+
+  void Function()? onDown;
+
+  VolumeListener({this.onUp, this.onDown});
+
+  StreamSubscription? stream;
+
+  void listen() {
+    stream = channel.receiveBroadcastStream().listen(onEvent);
+  }
+
+  void onEvent(event) {
+    if (event == 1) {
+      onUp!();
+    } else if (event == 2) {
+      onDown!();
+    }
+  }
+
+  void cancel() {
+    stream?.cancel();
+  }
+}