Android: Make input state changes observable

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/input/model/ControllerInterface.kt

@@ -6,6 +6,7 @@ import android.content.Context
 import android.hardware.input.InputManager
 import android.os.Build
 import android.os.Handler
+import android.os.Looper
 import android.os.VibrationEffect
 import android.os.Vibrator
 import android.os.VibratorManager
@@ -13,8 +14,11 @@ import android.view.InputDevice
 import android.view.KeyEvent
 import android.view.MotionEvent
 import androidx.annotation.Keep
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
 import org.dolphinemu.dolphinemu.DolphinApplication
 import org.dolphinemu.dolphinemu.utils.LooperThread
+import java.util.concurrent.atomic.AtomicBoolean
 
 /**
  * This class interfaces with the native ControllerInterface,
@@ -24,6 +28,12 @@ object ControllerInterface {
     private var inputDeviceListener: InputDeviceListener? = null
     private lateinit var looperThread: LooperThread
 
+    private var inputStateUpdatePending = AtomicBoolean(false)
+    private val inputStateVersion = MutableLiveData(0)
+
+    val inputStateChanged: LiveData<Int>
+        get() = inputStateVersion
+
     /**
      * Activities which want to pass on inputs to native code
      * should call this in their own dispatchKeyEvent method.
@@ -31,7 +41,13 @@ object ControllerInterface {
      * @return true if the emulator core seems to be interested in this event.
      * false if the event should be passed on to the default dispatchKeyEvent.
      */
-    external fun dispatchKeyEvent(event: KeyEvent): Boolean
+    fun dispatchKeyEvent(event: KeyEvent): Boolean {
+        val result = dispatchKeyEventNative(event)
+        onInputStateChanged()
+        return result
+    }
+
+    private external fun dispatchKeyEventNative(event: KeyEvent): Boolean
 
     /**
      * Activities which want to pass on inputs to native code
@@ -40,7 +56,13 @@ object ControllerInterface {
      * @return true if the emulator core seems to be interested in this event.
      * false if the event should be passed on to the default dispatchGenericMotionEvent.
      */
-    external fun dispatchGenericMotionEvent(event: MotionEvent): Boolean
+    fun dispatchGenericMotionEvent(event: MotionEvent): Boolean {
+        val result = dispatchGenericMotionEventNative(event)
+        onInputStateChanged()
+        return result
+    }
+
+    private external fun dispatchGenericMotionEventNative(event: MotionEvent): Boolean
 
     /**
      * [DolphinSensorEventListener] calls this for each axis of a received SensorEvent.
@@ -48,7 +70,13 @@ object ControllerInterface {
      * @return true if the emulator core seems to be interested in this event.
      * false if the sensor can be suspended to save battery.
      */
-    external fun dispatchSensorEvent(
+    fun dispatchSensorEvent(deviceQualifier: String, axisName: String, value: Float): Boolean {
+        val result = dispatchSensorEventNative(deviceQualifier, axisName, value)
+        onInputStateChanged()
+        return result
+    }
+
+    private external fun dispatchSensorEventNative(
         deviceQualifier: String,
         axisName: String,
         value: Float
@@ -76,6 +104,19 @@ object ControllerInterface {
 
     external fun getDevice(deviceString: String): CoreDevice?
 
+    private fun onInputStateChanged() {
+        // When a single SensorEvent is dispatched, this method is likely to get called many times.
+        // For the sake of performance, let's batch input state updates so that observers only have
+        // to process one update.
+        if (!inputStateUpdatePending.getAndSet(true)) {
+            Handler(Looper.getMainLooper()).post {
+                if (inputStateUpdatePending.getAndSet(false)) {
+                    inputStateVersion.value = inputStateVersion.value?.plus(1)
+                }
+            }
+        }
+    }
+
     @Keep
     @JvmStatic
     private fun registerInputDeviceListener() {

Source/Core/InputCommon/ControllerInterface/Android/Android.cpp

@@ -1002,7 +1002,7 @@ void InputBackend::PopulateDevices()
 extern "C" {
 
 JNIEXPORT jboolean JNICALL
-Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchKeyEvent(
+Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchKeyEventNative(
     JNIEnv* env, jclass, jobject key_event)
 {
   const jint action = env->CallIntMethod(key_event, s_key_event_get_action);
@@ -1046,7 +1046,7 @@ Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatch
 }
 
 JNIEXPORT jboolean JNICALL
-Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchGenericMotionEvent(
+Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchGenericMotionEventNative(
     JNIEnv* env, jclass, jobject motion_event)
 {
   const jint device_id = env->CallIntMethod(motion_event, s_input_event_get_device_id);
@@ -1090,7 +1090,7 @@ Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatch
 }
 
 JNIEXPORT jboolean JNICALL
-Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchSensorEvent(
+Java_org_dolphinemu_dolphinemu_features_input_model_ControllerInterface_dispatchSensorEventNative(
     JNIEnv* env, jclass, jstring j_device_qualifier, jstring j_axis_name, jfloat value)
 {
   ciface::Core::DeviceQualifier device_qualifier;