Implement proper pause and resume logic (#34)

app/src/main/cpp/emu_jni.cpp

@@ -165,6 +165,14 @@ extern "C" JNIEXPORT jboolean Java_emu_skyline_EmulationActivity_setSurface(JNIE
     return true;
 }
 
+extern "C" JNIEXPORT void Java_emu_skyline_EmulationActivity_pauseEmulation(JNIEnv *, jobject, jboolean pause) {
+    auto gpu = GpuWeak.lock();
+    if (!gpu) return;
+    if (pause) {
+        gpu->presentation.Pause();
+    } else gpu->presentation.Resume();
+}
+
 extern "C" JNIEXPORT void Java_emu_skyline_EmulationActivity_changeAudioStatus(JNIEnv *, jobject, jboolean play) {
     auto audio{AudioWeak.lock()};
     if (audio)

app/src/main/cpp/skyline/gpu/presentation_engine.cpp

@@ -21,6 +21,8 @@ extern jfloat AverageFrametimeDeviationMs;
 namespace skyline::gpu {
     using namespace service::hosbinder;
 
+    std::atomic<bool> paused{false};
+
     PresentationEngine::PresentationEngine(const DeviceState &state, GPU &gpu)
         : state{state},
           gpu{gpu},
@@ -76,7 +78,11 @@ namespace skyline::gpu {
         try {
             choreographerLooper = ALooper_prepare(0);
             AChoreographer_postFrameCallback64(AChoreographer_getInstance(), reinterpret_cast<AChoreographer_frameCallback64>(&ChoreographerCallback), this);
-            while (ALooper_pollAll(-1, nullptr, nullptr, nullptr) == ALOOPER_POLL_WAKE && !choreographerStop); // Will block and process callbacks till ALooper_wake() is called with choreographerStop set
+            while (ALooper_pollAll(-1, nullptr, nullptr, nullptr) == ALOOPER_POLL_WAKE && !choreographerStop) {
+                while (paused.load(std::memory_order_acquire)) {
+                    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+                }
+            }
         } catch (const signal::SignalException &e) {
             LOGE("{}\nStack Trace:{}", e.what(), state.loader->GetStackTrace(e.frames));
             if (state.process)
@@ -235,6 +241,9 @@ namespace skyline::gpu {
 
         try {
             presentQueue.Process([this](const PresentableFrame &frame) {
+                while (paused.load(std::memory_order_acquire)) {
+                    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+                }
                 PresentFrame(frame);
                 frame.presentCallback(); // We're calling the callback here as it's outside of all the locks in PresentFrame
                 skipSignal = true;
@@ -412,6 +421,16 @@ namespace skyline::gpu {
         return nextFrameId++;
     }
 
+    void PresentationEngine::Pause() {
+        paused.store(true, std::memory_order_release);
+        LOGI("PresentationEngine paused.");
+    }
+
+    void PresentationEngine::Resume() {
+        paused.store(false, std::memory_order_release);
+        LOGI("PresentationEngine resumed.");
+    }
+
     NativeWindowTransform PresentationEngine::GetTransformHint() {
         if (!vkSurface.has_value()) {
             std::unique_lock lock{mutex};

app/src/main/cpp/skyline/gpu/presentation_engine.h

@@ -115,6 +115,9 @@ namespace skyline::gpu {
          */
         void UpdateSurface(jobject newSurface);
 
+        void Pause();
+        void Resume();
+
         /**
          * @brief Queue the supplied texture to be presented to the screen
          * @param timestamp The earliest timestamp (relative to skyline::util::GetTickNs) at which the frame must be presented, it should be 0 when it doesn't matter

app/src/main/java/emu/skyline/EmulationActivity.kt

@@ -172,6 +172,8 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
      */
     private external fun stopEmulation(join : Boolean) : Boolean
 
+    private external fun pauseEmulation(pause: Boolean)
+
     /**
      * This sets the surface object in libskyline to the provided value, emulation is halted if set to null
      *
@@ -448,8 +450,8 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
         binding.inGameMenu.setNavigationItemSelectedListener {
             when (it.itemId) {
                 R.id.menu_emulation_resume -> {
-                    if (!isEmulatorPaused) {
-                        pauseEmulator()
+                    if (isEmulatorPaused) {
+                        resumeEmulator()
                         it.title = resources.getString(R.string.pause_emulation)
                         it.icon = ResourcesCompat.getDrawable(
                             resources,
@@ -457,7 +459,7 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
                             this.theme
                         )
                     } else {
-                        resumeEmulator()
+                        pauseEmulator()
                         it.title = resources.getString(R.string.resume_emulation)
                         it.icon = ResourcesCompat.getDrawable(
                             resources,
@@ -500,14 +502,14 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
     @SuppressWarnings("WeakerAccess")
     fun pauseEmulator() {
         if (isEmulatorPaused) return
-        setSurface(null)
+        pauseEmulation(true)
         changeAudioStatus(false)
         isEmulatorPaused = true
     }
 
     @SuppressWarnings("WeakerAccess")
     fun resumeEmulator() {
-        gameSurface?.let { setSurface(it) }
+        pauseEmulation(false)
         changeAudioStatus(true)
         isEmulatorPaused = false
     }