[Android] Turn page by volume keys

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();
+  }
+}