properly detect whether we are in "fullscreen" (i.e. immersive) on Android

jni/love/src/common/android.cpp

@@ -49,6 +49,24 @@ void setImmersive (bool immersive_active) {
 	env->DeleteLocalRef (clazz);
 }
 
+bool getImmersive () {
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+
+	jobject activity = (jobject) SDL_AndroidGetActivity();
+
+	jclass clazz (env->GetObjectClass(activity));
+	jmethodID method_id = env->GetMethodID (clazz, "getImmersiveMode", "()Z");
+
+	jboolean immersive_active = env->CallBooleanMethod (activity, method_id);
+
+	env->DeleteLocalRef (activity);
+	env->DeleteLocalRef (clazz);
+
+	if (immersive_active)
+		return true;
+	return false;
+}
+
 double getScreenScale()
 {
   static double result = -1.;

jni/love/src/common/android.h

@@ -32,7 +32,11 @@ namespace love
 namespace android
 {
 
+/**
+ * Enables or disables immersive mode where the navigation bar is hidden.
+ **/
 void setImmersive (bool immersive_active);
+bool getImmersive ();
 
 /**
  * Gets the scale factor of the window's screen, e.g. on Retina displays this