presenting in the ui thread

src/android/app/src/main/java/org/citra/citra_emu/NativeLibrary.java

@@ -172,6 +172,8 @@ public final class NativeLibrary {
 
     public static native void SurfaceDestroyed();
 
+    public static native void DoFrame();
+
     /**
      * Unpauses emulation from a paused state.
      */

src/android/app/src/main/java/org/citra/citra_emu/fragments/EmulationFragment.java

@@ -6,6 +6,7 @@ import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.os.Handler;
 import android.preference.PreferenceManager;
+import android.view.Choreographer;
 import android.view.LayoutInflater;
 import android.view.Surface;
 import android.view.SurfaceHolder;
@@ -30,7 +31,7 @@ import org.citra.citra_emu.utils.DirectoryStateReceiver;
 import org.citra.citra_emu.utils.EmulationMenuSettings;
 import org.citra.citra_emu.utils.Log;
 
-public final class EmulationFragment extends Fragment implements SurfaceHolder.Callback {
+public final class EmulationFragment extends Fragment implements SurfaceHolder.Callback, Choreographer.FrameCallback {
     private static final String KEY_GAMEPATH = "gamepath";
 
     private static final Handler perfStatsUpdateHandler = new Handler();
@@ -114,6 +115,7 @@ public final class EmulationFragment extends Fragment implements SurfaceHolder.C
     @Override
     public void onResume() {
         super.onResume();
+        Choreographer.getInstance().postFrameCallback(this);
         if (DirectoryInitialization.areCitraDirectoriesReady()) {
             mEmulationState.run(activity.isActivityRecreated());
         } else {
@@ -128,8 +130,11 @@ public final class EmulationFragment extends Fragment implements SurfaceHolder.C
             directoryStateReceiver = null;
         }
 
-        if (mEmulationState.isRunning())
+        if (mEmulationState.isRunning()) {
             mEmulationState.pause();
+        }
+
+        Choreographer.getInstance().removeFrameCallback(this);
         super.onPause();
     }
 
@@ -227,6 +232,12 @@ public final class EmulationFragment extends Fragment implements SurfaceHolder.C
         mEmulationState.clearSurface();
     }
 
+    @Override
+    public void doFrame(long frameTimeNanos) {
+        Choreographer.getInstance().postFrameCallback(this);
+        NativeLibrary.DoFrame();
+    }
+
     public void stopEmulation() {
         mEmulationState.stop();
     }
@@ -342,9 +353,9 @@ public final class EmulationFragment extends Fragment implements SurfaceHolder.C
         private void runWithValidSurface() {
             mRunWhenSurfaceIsValid = false;
             if (state == State.STOPPED) {
+                NativeLibrary.SurfaceChanged(mSurface);
                 Thread mEmulationThread = new Thread(() ->
                 {
-                    NativeLibrary.SurfaceChanged(mSurface);
                     Log.debug("[EmulationFragment] Starting emulation thread.");
                     NativeLibrary.Run(mGamePath);
                 }, "NativeEmulation");

src/android/app/src/main/jni/emu_window/emu_window.cpp

@@ -79,6 +79,7 @@ static void UpdateLandscapeScreenLayout() {
 
 void EmuWindow_Android::OnSurfaceChanged(ANativeWindow* surface) {
     render_window = surface;
+    StopPresenting();
 }
 
 bool EmuWindow_Android::OnTouchEvent(int x, int y, bool pressed) {
@@ -219,7 +220,6 @@ void EmuWindow_Android::DestroyContext() {
 }
 
 EmuWindow_Android::~EmuWindow_Android() {
-    StopPresenting();
     DestroyWindowSurface();
     DestroyContext();
 }
@@ -228,34 +228,27 @@ std::unique_ptr<Frontend::GraphicsContext> EmuWindow_Android::CreateSharedContex
     return std::make_unique<SharedContext_Android>(egl_display, egl_config, egl_context);
 }
 
-void EmuWindow_Android::StartPresenting() {
-    ASSERT(!presentation_thread);
-    is_presenting = true;
-    presentation_thread =
-        std::make_unique<std::thread>([emu_window{this}] { emu_window->Present(); });
-}
-
 void EmuWindow_Android::StopPresenting() {
-    is_presenting = false;
+    if (presenting_state == PresentingState::Running) {
-    if (presentation_thread) {
+        eglMakeCurrent(egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
-        presentation_thread->join();
-        presentation_thread.reset();
     }
+    presenting_state = PresentingState::Stopped;
 }
 
-bool EmuWindow_Android::IsPresenting() const {
+void EmuWindow_Android::TryPresenting() {
-    return is_presenting;
+    if (presenting_state != PresentingState::Running) {
-}
+        if (presenting_state == PresentingState::Initial) {
-
+            eglMakeCurrent(egl_display, egl_surface, egl_surface, egl_context);
-void EmuWindow_Android::Present() {
+            glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-    eglMakeCurrent(egl_display, egl_surface, egl_surface, egl_context);
+            presenting_state = PresentingState::Running;
-    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+        } else {
+            return;
+        }
+    }
     eglSwapInterval(egl_display, Settings::values.use_vsync_new ? 1 : 0);
-    while (IsPresenting()) {
+    if (VideoCore::g_renderer->TryPresent()) {
-        VideoCore::g_renderer->TryPresent(100);
         eglSwapBuffers(egl_display, egl_surface);
     }
-    eglMakeCurrent(egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
 }
 
 void EmuWindow_Android::PollEvents() {
@@ -266,14 +259,10 @@ void EmuWindow_Android::PollEvents() {
     host_window = render_window;
     render_window = nullptr;
 
-    if (IsPresenting()) {
-        StopPresenting();
-    }
-
     DestroyWindowSurface();
     CreateWindowSurface();
     OnFramebufferSizeChanged();
-    StartPresenting();
+    presenting_state = PresentingState::Initial;
 }
 
 void EmuWindow_Android::MakeCurrent() {

src/android/app/src/main/jni/emu_window/emu_window.h

@@ -4,7 +4,6 @@
 
 #pragma once
 
-#include <thread>
 #include <vector>
 
 #include <EGL/egl.h>
@@ -51,9 +50,8 @@ public:
     void MakeCurrent() override;
     void DoneCurrent() override;
 
-    void StartPresenting();
+    void TryPresenting();
     void StopPresenting();
-    bool IsPresenting() const;
 
     std::unique_ptr<GraphicsContext> CreateSharedContext() const override;
 
@@ -76,7 +74,10 @@ private:
 
     std::unique_ptr<Frontend::GraphicsContext> core_context;
 
-    std::unique_ptr<std::thread> presentation_thread;
+    enum class PresentingState {
-
+        Initial,
-    bool is_presenting{};
+        Running,
+        Stopped,
+    };
+    PresentingState presenting_state{};
 };

src/android/app/src/main/jni/native.cpp

@@ -102,7 +102,6 @@ static void TryShutdown() {
         return;
     }
 
-    window->StopPresenting();
     window->DoneCurrent();
     Core::System::GetInstance().Shutdown();
     window.reset();
@@ -167,8 +166,6 @@ static Core::System::ResultStatus RunCitra(const std::string& filepath) {
     is_running = true;
     pause_emulation = false;
 
-    window->StartPresenting();
-
     SCOPE_EXIT({ TryShutdown(); });
 
     // Audio stretching on Android is only useful with lower framerates, disable it when fullspeed
@@ -196,6 +193,7 @@ static Core::System::ResultStatus RunCitra(const std::string& filepath) {
 
             std::unique_lock<std::mutex> pause_lock(paused_mutex);
             running_cv.wait(pause_lock, [] { return !pause_emulation || !is_running; });
+            window->PollEvents();
         }
     }
 
@@ -225,6 +223,13 @@ void Java_org_citra_citra_1emu_NativeLibrary_SurfaceDestroyed(JNIEnv* env,
     }
 }
 
+void Java_org_citra_citra_1emu_NativeLibrary_DoFrame(JNIEnv* env, [[maybe_unused]] jclass clazz) {
+    if (!is_running || pause_emulation) {
+        return;
+    }
+    window->TryPresenting();
+}
+
 void Java_org_citra_citra_1emu_NativeLibrary_NotifyOrientationChange(JNIEnv* env,
                                                                      [[maybe_unused]] jclass clazz,
                                                                      jint layout_option,
@@ -302,6 +307,7 @@ void Java_org_citra_citra_1emu_NativeLibrary_StopEmulation(JNIEnv* env,
                                                            [[maybe_unused]] jclass clazz) {
     is_running = false;
     pause_emulation = false;
+    window->StopPresenting();
     running_cv.notify_all();
 }