Support new Wi-Fi locks in Android Q

README.md

@@ -65,8 +65,20 @@ Default settings are picked to suit general use cases and maximize compatibility
 
 * Keep Wi-Fi alive: Acquire Wi-Fi locks when repeater, temporary hotspot or system VPN hotspot is activated.
    - Choose "System default" to save battery life;
-   - Choose "On" (default) if repeater/hotspot turns itself off automatically or stops working after a while;
-   - Choose "High Performance Mode" to minimize packet loss and latency (will consume more power).
+   - (up to Android 9) Choose "On" (default) if repeater/hotspot turns itself off automatically or stops working after a while;
+   - (up to Android 9) Choose "High Performance Mode" to minimize packet loss and latency (will consume more power);
+   - (since Android Q) Choose "Disable power save" to decrease packet latency.
+     An example use case is when a voice connection needs to be kept active even after the device screen goes off.
+     Using this mode may improve the call quality.
+     Requires support from the hardware.
+   - (since Android Q) Choose "Low latency mode" to optimize for reduced packet latency, and this might result in:
+     1. Reduced battery life.
+     2. Reduced throughput.
+     3. Reduced frequency of Wi-Fi scanning.
+        This may cause the device not roaming or switching to the AP with highest signal quality, and location accuracy may be reduced.
+     Example use cases are real time gaming or virtual reality applications where low latency is a key factor for user experience.
+     Requires support from the hardware.
+     Note: Requires this app running in foreground with screen on.
 * Start repeater on boot: Self explanatory.
 * Network status monitor mode: This option controls how the app monitors connected devices as well as interface changes
   (when custom upstream is used).

mobile/src/main/java/be/mygod/vpnhotspot/MainActivity.kt

@@ -15,6 +15,7 @@ import be.mygod.vpnhotspot.client.ClientViewModel
 import be.mygod.vpnhotspot.client.ClientsFragment
 import be.mygod.vpnhotspot.databinding.ActivityMainBinding
 import be.mygod.vpnhotspot.manage.TetheringFragment
+import be.mygod.vpnhotspot.net.wifi.WifiDoubleLock
 import be.mygod.vpnhotspot.util.ServiceForegroundConnector
 import be.mygod.vpnhotspot.widget.SmartSnackbar
 import com.google.android.material.bottomnavigation.BottomNavigationMenuView
@@ -41,6 +42,7 @@ class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemS
         if (RepeaterService.supported) ServiceForegroundConnector(this, model, RepeaterService::class)
         model.clients.observe(this, Observer { badge.badgeNumber = it.size })
         SmartSnackbar.Register(lifecycle, binding.fragmentHolder)
+        WifiDoubleLock.ActivityListener(this)
     }
 
     override fun onNavigationItemSelected(item: MenuItem) = when (item.itemId) {

mobile/src/main/java/be/mygod/vpnhotspot/SettingsPreferenceFragment.kt

@@ -12,6 +12,7 @@ import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.net.Routing.Companion.IPTABLES
 import be.mygod.vpnhotspot.net.monitor.IpMonitor
 import be.mygod.vpnhotspot.net.monitor.UpstreamMonitor
+import be.mygod.vpnhotspot.net.wifi.WifiDoubleLock
 import be.mygod.vpnhotspot.preference.AlwaysAutoCompleteEditTextPreferenceDialogFragmentCompat
 import be.mygod.vpnhotspot.preference.SharedPreferenceDataStore
 import be.mygod.vpnhotspot.util.RootSession
@@ -26,6 +27,7 @@ import java.net.SocketException
 
 class SettingsPreferenceFragment : PreferenceFragmentCompat() {
     override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
+        WifiDoubleLock.mode = WifiDoubleLock.mode   // handle complicated default value and possible system upgrades
         preferenceManager.preferenceDataStore = SharedPreferenceDataStore(app.pref)
         RoutingManager.masqueradeMode = RoutingManager.masqueradeMode   // flush default value
         addPreferencesFromResource(R.xml.pref_settings)

mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiDoubleLock.kt

@@ -4,7 +4,15 @@ import android.annotation.SuppressLint
 import android.content.SharedPreferences
 import android.net.wifi.WifiManager
 import android.os.PowerManager
+import android.view.WindowManager
+import androidx.activity.ComponentActivity
+import androidx.annotation.RequiresApi
+import androidx.core.content.edit
 import androidx.core.content.getSystemService
+import androidx.core.os.BuildCompat
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleObserver
+import androidx.lifecycle.OnLifecycleEvent
 import be.mygod.vpnhotspot.App.Companion.app
 
 /**
@@ -13,8 +21,12 @@ import be.mygod.vpnhotspot.App.Companion.app
 class WifiDoubleLock(lockType: Int) : AutoCloseable {
     companion object : SharedPreferences.OnSharedPreferenceChangeListener {
         private const val KEY = "service.wifiLock"
-        private val lockType get() =
-            WifiDoubleLock.Mode.valueOf(app.pref.getString(KEY, WifiDoubleLock.Mode.Full.toString()) ?: "").lockType
+        var mode: Mode
+            @Suppress("DEPRECATION")
+            get() = Mode.valueOf(app.pref.getString(KEY, Mode.Full.toString()) ?: "").let {
+                if (it == Mode.Full && BuildCompat.isAtLeastQ()) Mode.None else it
+            }
+            set(value) = app.pref.edit { putString(KEY, value.toString()) }
         private val service by lazy { app.getSystemService<PowerManager>()!! }
 
         private var holders = mutableSetOf<Any>()
@@ -23,7 +35,7 @@ class WifiDoubleLock(lockType: Int) : AutoCloseable {
         fun acquire(holder: Any) = synchronized(this) {
             if (holders.isEmpty()) {
                 app.pref.registerOnSharedPreferenceChangeListener(this)
-                val lockType = lockType
+                val lockType = mode.lockType
                 if (lockType != null) lock = WifiDoubleLock(lockType)
             }
             check(holders.add(holder))
@@ -40,14 +52,45 @@ class WifiDoubleLock(lockType: Int) : AutoCloseable {
         override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
             if (key == KEY) synchronized(this) {
                 lock?.close()
-                val lockType = lockType
+                val lockType = mode.lockType
                 lock = if (lockType == null) null else WifiDoubleLock(lockType)
             }
         }
     }
 
-    enum class Mode(val lockType: Int? = null) {
-        None, Full(WifiManager.WIFI_MODE_FULL), HighPerf(WifiManager.WIFI_MODE_FULL_HIGH_PERF)
+    enum class Mode(val lockType: Int? = null, val keepScreenOn: Boolean = false) {
+        None,
+        @Suppress("DEPRECATION")
+        @Deprecated("This constant was deprecated in API level Q.\n" +
+                "This API is non-functional and will have no impact.")
+        Full(WifiManager.WIFI_MODE_FULL),
+        HighPerf(WifiManager.WIFI_MODE_FULL_HIGH_PERF),
+        @RequiresApi(29)
+        LowLatency(WifiManager.WIFI_MODE_FULL_LOW_LATENCY, true),
+    }
+
+    class ActivityListener(val activity: ComponentActivity) :
+            LifecycleObserver, SharedPreferences.OnSharedPreferenceChangeListener {
+        private var keepScreenOn: Boolean = false
+            set(value) {
+                if (field == value) return
+                field = value
+                if (value) activity.window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+                else activity.window.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+            }
+
+        init {
+            activity.lifecycle.addObserver(this)
+            app.pref.registerOnSharedPreferenceChangeListener(this)
+            keepScreenOn = mode.keepScreenOn
+        }
+
+        override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
+            if (key == KEY) keepScreenOn = mode.keepScreenOn
+        }
+
+        @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
+        fun shutdown() = app.pref.unregisterOnSharedPreferenceChangeListener(this)
     }
 
     private val wifi = app.wifi.createWifiLock(lockType, "vpnhotspot:wifi").apply { acquire() }

mobile/src/main/res/values-v29/arrays.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="settings_service_wifi_lock">
+        <item>@string/settings_service_wifi_lock_none</item>
+        <item>@string/settings_service_wifi_lock_high_perf_v29</item>
+        <item>@string/settings_service_wifi_lock_low_latency</item>
+    </string-array>
+    <string-array name="settings_service_wifi_lock_values">
+        <item>None</item>
+        <item>HighPerf</item>
+        <item>LowLatency</item>
+    </string-array>
+</resources>

mobile/src/main/res/values/strings.xml

@@ -101,6 +101,8 @@
     <string name="settings_service_wifi_lock_none">System default</string>
     <string name="settings_service_wifi_lock_full">On</string>
     <string name="settings_service_wifi_lock_high_perf">High Performance Mode</string>
+    <string name="settings_service_wifi_lock_high_perf_v29">Disable power save</string>
+    <string name="settings_service_wifi_lock_low_latency">Low latency mode</string>
     <string name="settings_service_ip_monitor">Network status monitor mode</string>
     <string name="settings_service_ip_monitor_monitor">Netlink monitor</string>
     <string name="settings_service_ip_monitor_monitor_root">Netlink monitor with root</string>

mobile/src/main/res/xml/pref_settings.xml

@@ -41,7 +41,6 @@
             app:icon="@drawable/ic_device_wifi_lock"
             app:entries="@array/settings_service_wifi_lock"
             app:entryValues="@array/settings_service_wifi_lock_values"
-            app:defaultValue="Full"
             app:title="@string/settings_service_wifi_lock"
             app:useSimpleSummaryProvider="true"/>
         <SwitchPreference