Introduce AndroidSettings class and use inheritance

The `Settings` class now has a pure virtual `Update` method, and uses inheritance over template specialization for platform-specific behavior override.

app/CMakeLists.txt

@@ -134,7 +134,6 @@ add_library(skyline SHARED
         ${source_DIR}/skyline/common.cpp
         ${source_DIR}/skyline/common/exception.cpp
         ${source_DIR}/skyline/common/logger.cpp
-        ${source_DIR}/skyline/common/settings.cpp
         ${source_DIR}/skyline/common/signal.cpp
         ${source_DIR}/skyline/common/uuid.cpp
         ${source_DIR}/skyline/common/trace.cpp

app/src/main/cpp/emu_jni.cpp

@@ -8,7 +8,7 @@
 #include "skyline/common.h"
 #include "skyline/common/language.h"
 #include "skyline/common/signal.h"
-#include "skyline/common/settings.h"
+#include "skyline/common/android_settings.h"
 #include "skyline/common/trace.h"
 #include "skyline/loader/loader.h"
 #include "skyline/vfs/android_asset_filesystem.h"
@@ -54,14 +54,6 @@ static std::string GetTimeZoneName() {
     return "GMT";
 }
 
-template<> void skyline::Settings::Update<skyline::KtSettings>(KtSettings newSettings) {
-    isDocked = newSettings.GetBool("isDocked");
-    usernameValue = newSettings.GetString("usernameValue");
-    systemLanguage = newSettings.GetInt<skyline::language::SystemLanguage>("systemLanguage");
-    forceTripleBuffering = newSettings.GetBool("forceTripleBuffering");
-    disableFrameThrottling = newSettings.GetBool("disableFrameThrottling");
-}
-
 extern "C" JNIEXPORT void Java_emu_skyline_SkylineApplication_initializeLog(
     JNIEnv *env,
     jobject,
@@ -93,8 +85,7 @@ extern "C" JNIEXPORT void Java_emu_skyline_EmulationActivity_executeApplication(
 
     auto jvmManager{std::make_shared<skyline::JvmManager>(env, instance)};
 
-    skyline::KtSettings ktSettings{env, settingsInstance};
-    auto settings{std::make_shared<skyline::Settings>(ktSettings)};
+    std::shared_ptr<skyline::Settings> settings{std::make_shared<skyline::AndroidSettings>(env, settingsInstance)};
 
     skyline::JniString publicAppFilesPath(env, publicAppFilesPathJstring);
     skyline::Logger::EmulationContext.Initialize(publicAppFilesPath + "logs/emulation.sklog");
@@ -240,10 +231,9 @@ extern "C" JNIEXPORT void JNICALL Java_emu_skyline_EmulationActivity_setTouchSta
     env->ReleaseIntArrayElements(pointsJni, reinterpret_cast<jint *>(points.data()), JNI_ABORT);
 }
 
-extern "C" JNIEXPORT void JNICALL Java_emu_skyline_utils_SettingsValues_updateNative(JNIEnv *env, jobject settingsInstance) {
+extern "C" JNIEXPORT void JNICALL Java_emu_skyline_utils_SettingsValues_updateNative(JNIEnv *env, jobject) {
     auto settings{SettingsWeak.lock()};
     if (!settings)
         return; // We don't mind if we miss settings updates while settings haven't been initialized
-    skyline::KtSettings ktSettings{env, settingsInstance};
-    settings->Update(ktSettings);
+    settings->Update();
 }

app/src/main/cpp/skyline/common/android_settings.h

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright © 2022 Skyline Team and Contributors (https://github.com/skyline-emu/)
+
+#pragma once
+
+#include "settings.h"
+#include "jvm.h"
+
+namespace skyline {
+    /**
+     * @brief Handles settings on the android platform
+     * @note Lifetime of this class must not exceed the one of the JNIEnv contained inside ktSettings
+     */
+    class AndroidSettings final : public Settings {
+      private:
+        KtSettings ktSettings;
+
+      public:
+        /**
+         * @note Will construct the underlying KtSettings object in-place
+         */
+        AndroidSettings(JNIEnv *env, jobject settingsInstance) : ktSettings(env, settingsInstance) {
+            Update();
+        }
+
+        /**
+         * @note Will take ownership of the passed KtSettings object
+         */
+        AndroidSettings(KtSettings &&ktSettings) : ktSettings(std::move(ktSettings)) {
+            Update();
+        }
+
+        void Update() override {
+            isDocked = ktSettings.GetBool("isDocked");
+            usernameValue = std::move(ktSettings.GetString("usernameValue"));
+            systemLanguage = ktSettings.GetInt<skyline::language::SystemLanguage>("systemLanguage");
+            forceTripleBuffering = ktSettings.GetBool("forceTripleBuffering");
+            disableFrameThrottling = ktSettings.GetBool("disableFrameThrottling");
+        };
+    };
+}

app/src/main/cpp/skyline/common/settings.cpp

@@ -1,12 +0,0 @@
-// SPDX-License-Identifier: MPL-2.0
-// Copyright © 2020 Skyline Team and Contributors (https://github.com/skyline-emu/)
-
-#include "settings.h"
-
-namespace skyline {
-    /**
-     * @note This is a placeholder implementation, it must be overridden via template specialisation for platform-specific behavior
-     */
-    template<class T>
-    void Settings::Update(T newSettings) {}
-}

app/src/main/cpp/skyline/common/settings.h

@@ -7,7 +7,7 @@
 
 namespace skyline {
     /**
-     * @brief The Settings class is used to access preferences set in the Kotlin component of Skyline
+     * @brief The Settings class provides a simple interface to access user-defined settings, update values and subscribe callbacks to observe changes.
      */
     class Settings {
         template<typename T>
@@ -60,16 +60,14 @@ namespace skyline {
         Setting<bool> forceTripleBuffering; //!< If the presentation engine should always triple buffer even if the swapchain supports double buffering
         Setting<bool> disableFrameThrottling; //!< Allow the guest to submit frames without any blocking calls
 
-        template<class T>
-        Settings(T settings) {
-            Update(settings);
-        }
+        Settings() = default;
+
+        virtual ~Settings() = default;
 
         /**
          * @brief Updates settings with the given values
-         * @param newSettings A platform-specific object containing the new settings' values
+         * @note This method is platform-specific and must be overridden
          */
-        template<class T>
-        void Update(T newSettings);
+        virtual void Update() = 0;
     };
 }

app/src/main/cpp/skyline/jvm.h

@@ -21,6 +21,7 @@ namespace skyline {
     /**
      * @brief A wrapper over the `Settings` Kotlin class
      * @note The lifetime of this class must not exceed that of the JNI environment
+     * @note Copy construction of this class is disallowed to avoid issues with the JNI environment lifetime
      */
     class KtSettings {
       private:
@@ -31,6 +32,12 @@ namespace skyline {
       public:
         KtSettings(JNIEnv *env, jobject settingsInstance) : env(env), settingsInstance(settingsInstance), settingsClass(env->GetObjectClass(settingsInstance)) {}
 
+        KtSettings(const KtSettings &) = delete;
+
+        void operator=(const KtSettings &) = delete;
+
+        KtSettings(KtSettings &&) = default;
+
         /**
          * @param key A null terminated string containing the key of the setting to get
          */