JUCE/modules/juce_events/native/juce_Messaging_android.cpp

/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
namespace Android
{
    class Runnable : public juce::AndroidInterfaceImplementer
    {
    public:
        virtual void run() = 0;

    private:
        jobject invoke (jobject proxy, jobject method, jobjectArray args) override
        {
            auto* env = getEnv();
            auto methodName = juce::juceString ((jstring) env->CallObjectMethod (method, JavaMethod.getName));

            if (methodName == "run")
            {
                run();
                return nullptr;
            }

            // invoke base class
            return AndroidInterfaceImplementer::invoke (proxy, method, args);
        }
    };

    struct Handler
    {
        Handler() = default;
        ~Handler() { clearSingletonInstance(); }

        JUCE_DECLARE_SINGLETON_INLINE (Handler, false)

        bool post (jobject runnable)
        {
            return (getEnv()->CallBooleanMethod (nativeHandler.get(), AndroidHandler.post, runnable) != 0);
        }

        GlobalRef nativeHandler { LocalRef<jobject> { getEnv()->NewObject (AndroidHandler, AndroidHandler.constructor) } };
    };
}

//==============================================================================
struct AndroidMessageQueue final : private Android::Runnable
{
    JUCE_DECLARE_SINGLETON_SINGLETHREADED_INLINE (AndroidMessageQueue, true)

    AndroidMessageQueue() = default;

    ~AndroidMessageQueue() override
    {
        JUCE_ASSERT_MESSAGE_THREAD
        clearSingletonInstance();
    }

    bool post (MessageManager::MessageBase::Ptr&& message)
    {
        queue.add (std::move (message));

        // this will call us on the message thread
        return handler.post (self.get());
    }

private:

    void run() override
    {
        for (;;)
        {
            MessageManager::MessageBase::Ptr message (queue.removeAndReturn (0));

            if (message == nullptr)
                break;

            message->messageCallback();
        }
    }

    ReferenceCountedArray<MessageManager::MessageBase, CriticalSection> queue;
    Android::Handler handler;

    // the this pointer to this class in Java land
    GlobalRef self { CreateJavaInterface (this, "java/lang/Runnable") };
};

//==============================================================================
void MessageManager::doPlatformSpecificInitialisation() { AndroidMessageQueue::getInstance(); }
void MessageManager::doPlatformSpecificShutdown()       { AndroidMessageQueue::deleteInstance(); }

bool MessageManager::postMessageToSystemQueue (MessageManager::MessageBase* const message)
{
    return AndroidMessageQueue::getInstance()->post (message);
}

//==============================================================================
void MessageManager::broadcastMessage (const String&)
{
}

void MessageManager::runDispatchLoop()
{
}

void MessageManager::stopDispatchLoop()
{
    struct QuitCallback final : public CallbackMessage
    {
        QuitCallback() {}

        void messageCallback() override
        {
            auto* env = getEnv();
            auto activity = getCurrentActivity();

            if (activity != nullptr)
            {
                jmethodID quitMethod = env->GetMethodID (AndroidActivity, "finishAndRemoveTask", "()V");

                if (quitMethod != nullptr)
                {
                    env->CallVoidMethod (activity.get(), quitMethod);
                    return;
                }

                quitMethod = env->GetMethodID (AndroidActivity, "finish", "()V");
                jassert (quitMethod != nullptr);
                env->CallVoidMethod (activity.get(), quitMethod);
            }
            else
            {
                jassertfalse;
            }
        }
    };

    (new QuitCallback())->post();
    quitMessagePosted = true;
}

//==============================================================================
class JuceAppLifecycle final : public ActivityLifecycleCallbacks
{
public:
    using CreateApp = juce::JUCEApplicationBase* (*)();

    explicit JuceAppLifecycle (CreateApp initSymbolAddr)
        : createApplicationSymbol (initSymbolAddr)
    {
    }

    void onActivityCreated (jobject, jobject) override
    {
        checkCreated();
    }

    void onActivityDestroyed (jobject activity) override
    {
        auto* env = getEnv();

        // if the main activity is being destroyed, only then tear-down JUCE
        if (env->IsSameObject (getMainActivity().get(), activity) != 0)
        {
            JUCEApplicationBase::appWillTerminateByForce();
            JNIClassBase::releaseAllClasses (env);

            LocalRef<jclass> systemClass { env->FindClass ("java/lang/System") };
            jmethodID exitMethod = env->GetStaticMethodID (systemClass.get(), "exit", "(I)V");
            env->CallStaticVoidMethod (systemClass, exitMethod, 0);
        }
    }

    void onActivityStarted (jobject) override
    {
        checkCreated();
    }

    void onActivityPaused (jobject) override
    {
        if (auto* app = JUCEApplicationBase::getInstance())
            app->suspended();
    }

    void onActivityResumed (jobject) override
    {
        checkInitialised();

        if (auto* app = JUCEApplicationBase::getInstance())
            app->resumed();
    }

    static JuceAppLifecycle& getInstance (CreateApp initSymbolAddr)
    {
        static JuceAppLifecycle juceAppLifecycle (initSymbolAddr);
        return juceAppLifecycle;
    }

private:
    void checkCreated()
    {
        if (JUCEApplicationBase::getInstance() == nullptr)
        {
            DBG (SystemStats::getJUCEVersion());

            JUCEApplicationBase::createInstance = createApplicationSymbol;

            initialiser.emplace();

            if (! JUCEApplicationBase::createInstance())
                jassertfalse; // you must supply an application object for an android app!

            jassert (MessageManager::getInstance()->isThisTheMessageThread());
        }
    }

    void checkInitialised()
    {
        checkCreated();

        if (! hasBeenInitialised)
        {
            if (auto* app = JUCEApplicationBase::getInstance())
            {
                hasBeenInitialised = app->initialiseApp();

                if (! hasBeenInitialised)
                    exit (app->shutdownApp());
            }
        }
    }

    std::optional<ScopedJuceInitialiser_GUI> initialiser;
    GlobalRef myself;
    CreateApp createApplicationSymbol{};
    bool hasBeenInitialised = false;
    ActivityLifecycleCallbackForwarder forwarder { GlobalRef { getAppContext() }, this };
};

//==============================================================================
File juce_getExecutableFile();

void juce_juceEventsAndroidStartApp();
void juce_juceEventsAndroidStartApp()
{
    auto dllPath = juce_getExecutableFile().getFullPathName();
    auto addr = reinterpret_cast<juce::JUCEApplicationBase* (*)()> (DynamicLibrary (dllPath)
                                                                     .getFunction ("juce_CreateApplication"));

    if (addr != nullptr)
        JuceAppLifecycle::getInstance (addr);
}

} // namespace juce