Implement access to Java methods for C++ side

This commit implements the needed methods for the ARCoreInterface class such as 
* `get_activity()`
* `get_surface()`
* `is_activity_resumed()`
* `get_display_rotation()` -> will be added in ongoing upstream PR: godotengine/godot#77559

Author: paddy-exe

plugin/src/main/cpp/android_util.h

@@ -3,7 +3,7 @@
 
 #include <android/log.h>
 
-#define LOG_TAG "GodotOpenXRPlugin"
+#define LOG_TAG "ARCorePlugin"
 
 #define ALOG_ASSERT(_cond, ...) \
 	if (!(_cond))               \

plugin/src/main/cpp/jni/arcore_jni.cpp

@@ -10,8 +10,8 @@
 #define JNI_CLASS_NAME ARCorePlugin
 
 extern "C" {
-    JNIEXPORT void JNICALL JNI_METHOD(initializeWrapper)(JNIEnv *env, jobject object) {
-        ARCorePluginWrapper::initialize_wrapper(env, object);
+    JNIEXPORT void JNICALL JNI_METHOD(initializeWrapper)(JNIEnv *env, jobject arcore_plugin, jobject activity, jobject godot_instance) {
+        ARCorePluginWrapper::initialize_wrapper(env, activity, godot_instance, arcore_plugin);
     }
 
     JNIEXPORT void JNICALL JNI_METHOD(uninitializeWrapper)(JNIEnv *env, jobject) {

plugin/src/main/cpp/jni/arcore_plugin_wrapper.cpp

@@ -2,25 +2,87 @@
 
 #include "../android_util.h"
 #include <godot_cpp/godot.hpp>
+#include <godot_cpp/classes/os.hpp>
 
 jobject ARCorePluginWrapper::arcore_plugin_instance = nullptr;
 
-ARCorePluginWrapper::ARCorePluginWrapper() {}
+ARCorePluginWrapper::ARCorePluginWrapper() {
+    _get_surface = nullptr;
+    _is_activity_resumed = nullptr;
+    _get_display_rotation = nullptr;
+}
 
 ARCorePluginWrapper::~ARCorePluginWrapper() {}
 
-void ARCorePluginWrapper::initialize_wrapper(JNIEnv *env, jobject arcore_plugin) {
-    arcore_plugin_instance = env->NewGlobalRef(arcore_plugin);
+void ARCorePluginWrapper::initialize_wrapper(JNIEnv *p_env, jobject p_activity, jobject p_godot_instance, jobject p_arcore_plugin) {
+    arcore_plugin_instance = p_env->NewGlobalRef(p_arcore_plugin);
     ALOG_ASSERT(arcore_plugin_instance, "Invalid jobject value.");
 
-    jclass arcore_plugin_class = env->GetObjectClass(arcore_plugin_instance);
+    jclass arcore_plugin_class = p_env->GetObjectClass(arcore_plugin_instance);
     ALOG_ASSERT(arcore_plugin_class, "Invalid jclass value.");
+
+    godot_instance = p_env->NewGlobalRef(p_godot_instance);
+    activity = p_env->NewGlobalRef(p_activity);
+
+    // get info about our Godot class so we can get pointers and stuff...
+    godot_class = p_env->FindClass("org/godotengine/godot/Godot");
+    if (godot_class) {
+        godot_class = (jclass)p_env->NewGlobalRef(godot_class);
+    } else {
+        // this is a pretty serious fail.. bail... pointers will stay 0
+        return;
+    }
+    activity_class = p_env->FindClass("android/app/Activity");
+    if (activity_class) {
+        activity_class = (jclass)p_env->NewGlobalRef(activity_class);
+    } else {
+        // this is a pretty serious fail.. bail... pointers will stay 0
+        return;
+    }
+
+    // get some Godot method pointers...
+    _get_surface = p_env->GetMethodID(godot_class, "getSurface", "()Landroid/view/Surface;");
+    _is_activity_resumed = p_env->GetMethodID(godot_class, "isActivityResumed", "()Z");
+    _get_display_rotation = p_env->GetMethodID(godot_class, "getDisplayRotation", "()I");
 }
 
 void ARCorePluginWrapper::uninitialize_wrapper(JNIEnv *env) {
     if (arcore_plugin_instance) {
         env->DeleteGlobalRef(arcore_plugin_instance);
 
         arcore_plugin_instance = nullptr;
+
+        env->DeleteGlobalRef(godot_instance);
+        env->DeleteGlobalRef(godot_class);
+        env->DeleteGlobalRef(activity);
+        env->DeleteGlobalRef(activity_class);
+    }
+}
+
+jobject ARCorePluginWrapper::get_activity() {
+    return activity;
+}
+
+jobject ARCorePluginWrapper::get_surface(JNIEnv *p_env) {
+    if (_get_surface) {
+        return p_env->CallObjectMethod(godot_instance, _get_surface);
+    } else {
+        return nullptr;
+    }
+}
+
+bool ARCorePluginWrapper::is_activity_resumed(JNIEnv *p_env) {
+    if (_is_activity_resumed) {
+        return p_env->CallBooleanMethod(godot_instance, _is_activity_resumed);
+    } else {
+        return false;
+    }
+}
+
+int ARCorePluginWrapper::get_display_rotation(JNIEnv *p_env) {
+    if (_get_display_rotation) {
+        return p_env->CallIntMethod(godot_instance, _get_display_rotation);
+    } else {
+        return 0;
     }
 }

plugin/src/main/cpp/jni/arcore_plugin_wrapper.h

@@ -5,16 +5,29 @@
 
 class ARCorePluginWrapper {
 public:
-    static void initialize_wrapper(JNIEnv *env, jobject arcore_plugin);
+    static void initialize_wrapper(JNIEnv *env, jobject activity, jobject p_godot_instance, jobject arcore_plugin);
 
     static void uninitialize_wrapper(JNIEnv *env);
 
-
 private:
+    static jobject arcore_plugin_instance;
+    static jobject godot_instance;
+    static jobject activity;
+    static jclass godot_class;
+    static jclass activity_class;
+
+    static jmethodID _get_surface;
+    static jmethodID _is_activity_resumed;
+    static jmethodID _get_display_rotation;
+
+public:
     ARCorePluginWrapper();
     ~ARCorePluginWrapper();
 
-    static jobject arcore_plugin_instance;
+    jobject get_activity();
+    jobject get_surface(JNIEnv *p_env);
+    bool is_activity_resumed(JNIEnv *p_env);
+    int get_display_rotation(JNIEnv *p_env);
 };
 
 #endif // ARCORE_PLUGIN_WRAPPER_H

plugin/src/main/cpp/jni/jni_util.h

@@ -3,8 +3,8 @@
 
 #include <jni.h>
 #include <godot_cpp/variant/array.hpp>
-#include <godot_cpp/core/variant/string.hpp>
-#include <godot_cpp/core/variant/variant.hpp>
+#include <godot_cpp/variant/string.hpp>
+#include <godot_cpp/variant/variant.hpp>
 #include <vector>
 
 /** Auxiliary macros */

plugin/src/main/java/org/godotengine/plugin/arcore/ARCorePlugin.java

@@ -40,7 +40,7 @@ public Set<String> getPluginGDExtensionLibrariesPaths() {
 		return Set.of("addons/godot_arcore/godot_arcore.gdextension");
 	}
 
-	private native void initializeWrapper();
+	private native void initializeWrapper(Activity activity, Godot godot_instance);
 
     private native void uninitializeWrapper();
 }

plugin/src/main/java/org/godotengine/plugin/arcore/ARCoreSetupActivity.java

@@ -12,6 +12,8 @@
 
 /**
  * Activity used to setup ARCore prior to initializing the Godot engine.
+ *
+ * Needs to be refactored since Godot itself won't be an activity itself.
  */
 public class ARCoreSetupActivity extends Activity {
 	static final String PREVIOUS_ACTIVITY_START_INTENT_KEY = "previous_activity_start_intent";