android: Support for using device's set display refresh rate

* Adds support for querying the device's currently set display refresh rate to
  be used for android driver on creation. Allowing for devices which support
  selecting other refresh rate modes beyond 60hz.
* Changes hardcoded sensor polling rate to now match refresh queried from the
  device.

src/xrt/auxiliary/android/android_custom_surface.cpp

@@ -175,6 +175,11 @@ android_custom_surface_get_display_metrics(struct _JavaVM *vm,
 		MonadoView::staticInitClass((jclass)clazz.object().getHandle());
 
 		jni::Object displayMetrics = MonadoView::getDisplayMetrics(Activity((jobject)activity));
+		//! @todo implement non-deprecated codepath for api 30+
+		float displayRefreshRate = MonadoView::getDisplayRefreshRate(Activity((jobject)activity));
+		if (displayRefreshRate == 0.0) {
+			displayRefreshRate = 60.0f;
+		}
 
 		*out_metrics = {.width_pixels = displayMetrics.get<int>("widthPixels"),
 		                .height_pixels = displayMetrics.get<int>("heightPixels"),
@@ -182,7 +187,8 @@ android_custom_surface_get_display_metrics(struct _JavaVM *vm,
 		                .density = displayMetrics.get<float>("xdpi"),
 		                .scaled_density = displayMetrics.get<float>("ydpi"),
 		                .xdpi = displayMetrics.get<float>("density"),
-		                .ydpi = displayMetrics.get<float>("scaledDensity")};
+		                .ydpi = displayMetrics.get<float>("scaledDensity"),
+		                .refresh_rate = displayRefreshRate};
 		return true;
 
 	} catch (std::exception const &e) {

src/xrt/auxiliary/android/android_custom_surface.h

@@ -32,6 +32,7 @@ struct xrt_android_display_metrics
 	float scaled_density;
 	float xdpi;
 	float ydpi;
+	float refresh_rate;
 };
 
 /*!

src/xrt/auxiliary/android/org.freedesktop.monado.auxiliary.cpp

@@ -20,6 +20,7 @@ namespace org::freedesktop::monado::auxiliary {
 	          "attachToActivity", "(Landroid/app/Activity;)Lorg/freedesktop/monado/auxiliary/MonadoView;")),
 	      getDisplayMetrics(classRef().getStaticMethod("getDisplayMetrics",
 	                                                   "(Landroid/app/Activity;)Landroid/util/DisplayMetrics;")),
+	      getDisplayRefreshRate(classRef().getStaticMethod("getDisplayRefreshRate", "(Landroid/app/Activity;)F")),
 	      getNativePointer(classRef().getMethod("getNativePointer", "()J")),
 	      markAsDiscardedByNative(classRef().getMethod("markAsDiscardedByNative", "()V")),
 	      waitGetSurfaceHolder(classRef().getMethod("waitGetSurfaceHolder", "(I)Landroid/view/SurfaceHolder;"))

src/xrt/auxiliary/android/org.freedesktop.monado.auxiliary.hpp

@@ -86,6 +86,18 @@ namespace org::freedesktop::monado::auxiliary {
 		static jni::Object
 		getDisplayMetrics(android::app::Activity const &activity);
 
+		/*!
+		 * Wrapper for the getDisplayRefreshRate static method
+		 *
+		 * Java prototype:
+		 * `public static float getDisplayRefreshRate(android.app.Activity);`
+		 *
+		 * JNI signature: (Landroid/app/Activity;)F;
+		 *
+		 */
+		static float
+		getDisplayRefreshRate(android::app::Activity const &activity);
+
 		/*!
 		 * Wrapper for the getNativePointer method
 		 *
@@ -140,6 +152,7 @@ namespace org::freedesktop::monado::auxiliary {
 			jni::method_t attachToActivity;
 			jni::method_t attachToActivity1;
 			jni::method_t getDisplayMetrics;
+			jni::method_t getDisplayRefreshRate;
 			jni::method_t getNativePointer;
 			jni::method_t markAsDiscardedByNative;
 			jni::method_t waitGetSurfaceHolder;

src/xrt/auxiliary/android/org.freedesktop.monado.auxiliary.impl.hpp

@@ -37,6 +37,12 @@ namespace org::freedesktop::monado::auxiliary {
 		return Meta::data().clazz().call<jni::Object>(Meta::data().getDisplayMetrics, activity.object());
 	}
 
+	inline float
+	MonadoView::getDisplayRefreshRate(android::app::Activity const &activity)
+	{
+		return Meta::data().clazz().call<float>(Meta::data().getDisplayRefreshRate, activity.object());
+	}
+
 	inline void *
 	MonadoView::getNativePointer()
 	{

src/xrt/auxiliary/android/src/main/java/org/freedesktop/monado/auxiliary/MonadoView.java

@@ -106,6 +106,11 @@ public class MonadoView extends SurfaceView implements SurfaceHolder.Callback, S
         return displayMetrics;
     }
 
+    @Keep
+    public static float getDisplayRefreshRate(Activity activity) {
+        return activity.getWindowManager().getDefaultDisplay().getRefreshRate();
+    }
+
     @Keep
     public long getNativePointer() {
         if (nativeCounterpart == null) {

src/xrt/drivers/android/android_sensors.c

@@ -82,10 +82,19 @@ android_sensor_callback(int fd, int events, void *data)
 	return 1;
 }
 
+static inline int32_t
+android_get_sensor_poll_rate(const struct android_device *d)
+{
+	const float freq_multiplier = 3.0f;
+	return (d == NULL) ? POLL_RATE_USEC
+	                   : (int32_t)(d->base.hmd->screens[0].nominal_frame_interval_ns * freq_multiplier * 0.001f);
+}
+
 static void *
 android_run_thread(void *ptr)
 {
 	struct android_device *d = (struct android_device *)ptr;
+	const int32_t poll_rate_usec = android_get_sensor_poll_rate(d);
 
 #if __ANDROID_API__ >= 26
 	d->sensor_manager = ASensorManager_getInstanceForPackage(XRT_ANDROID_PACKAGE);
@@ -104,11 +113,11 @@ android_run_thread(void *ptr)
 	// Start sensors in case this was not done already.
 	if (d->accelerometer != NULL) {
 		ASensorEventQueue_enableSensor(d->event_queue, d->accelerometer);
-		ASensorEventQueue_setEventRate(d->event_queue, d->accelerometer, POLL_RATE_USEC);
+		ASensorEventQueue_setEventRate(d->event_queue, d->accelerometer, poll_rate_usec);
 	}
 	if (d->gyroscope != NULL) {
 		ASensorEventQueue_enableSensor(d->event_queue, d->gyroscope);
-		ASensorEventQueue_setEventRate(d->event_queue, d->gyroscope, POLL_RATE_USEC);
+		ASensorEventQueue_setEventRate(d->event_queue, d->gyroscope, poll_rate_usec);
 	}
 
 	int ret = 0;
@@ -234,8 +243,11 @@ android_device_create()
 		metrics.width_pixels = 2960;
 		metrics.height_pixels = 1440;
 		metrics.density_dpi = 572;
+		metrics.refresh_rate = 60.0f;
 	}
 
+	d->base.hmd->screens[0].nominal_frame_interval_ns = time_s_to_ns(1.0f / metrics.refresh_rate);
+
 	const uint32_t w_pixels = metrics.width_pixels;
 	const uint32_t h_pixels = metrics.height_pixels;
 	const uint32_t ppi = metrics.density_dpi;