Merge pull request #4940 from jroweboy/presentation-thread

Split Presentation thread from Render thread

src/citra_qt/bootmanager.cpp

@@ -1,31 +1,50 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
 #include <QApplication>
+#include <QDragEnterEvent>
 #include <QHBoxLayout>
 #include <QKeyEvent>
+#include <QOffscreenSurface>
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+#include <QOpenGLFunctions_3_3_Core>
+#include <QOpenGLWindow>
 #include <QScreen>
 #include <QWindow>
 #include <fmt/format.h>
-
 #include "citra_qt/bootmanager.h"
+#include "citra_qt/main.h"
 #include "common/microprofile.h"
 #include "common/scm_rev.h"
 #include "core/3ds.h"
 #include "core/core.h"
+#include "core/frontend/scope_acquire_context.h"
 #include "core/settings.h"
 #include "input_common/keyboard.h"
 #include "input_common/main.h"
 #include "input_common/motion_emu.h"
 #include "network/network.h"
+#include "video_core/renderer_base.h"
 #include "video_core/video_core.h"
 
-EmuThread::EmuThread(GRenderWindow* render_window) : render_window(render_window) {}
+EmuThread::EmuThread(Frontend::GraphicsContext& core_context) : core_context(core_context) {}
 
 EmuThread::~EmuThread() = default;
 
+static GMainWindow* GetMainWindow() {
+    for (QWidget* w : qApp->topLevelWidgets()) {
+        if (GMainWindow* main = qobject_cast<GMainWindow*>(w)) {
+            return main;
+        }
+    }
+    return nullptr;
+}
+
 void EmuThread::run() {
-    render_window->MakeCurrent();
-
     MicroProfileOnThreadCreate("EmuThread");
-
+    Frontend::ScopeAcquireContext scope(core_context);
     // Holds whether the cpu was running during the last iteration,
     // so that the DebugModeLeft signal can be emitted before the
     // next execution step.
@@ -72,48 +91,104 @@ void EmuThread::run() {
 #if MICROPROFILE_ENABLED
     MicroProfileOnThreadExit();
 #endif
-
-    render_window->moveContext();
 }
 
-// This class overrides paintEvent and resizeEvent to prevent the GUI thread from stealing GL
-// context.
-// The corresponding functionality is handled in EmuThread instead
-class GGLWidgetInternal : public QGLWidget {
-public:
-    GGLWidgetInternal(QGLFormat fmt, GRenderWindow* parent)
-        : QGLWidget(fmt, parent), parent(parent) {}
+OpenGLWindow::OpenGLWindow(QWindow* parent, QWidget* event_handler, QOpenGLContext* shared_context)
+    : QWindow(parent), event_handler(event_handler),
+      context(new QOpenGLContext(shared_context->parent())) {
 
-    void paintEvent(QPaintEvent* ev) override {
-        if (do_painting) {
-            QPainter painter(this);
-        }
-    }
+    // disable vsync for any shared contexts
+    auto format = shared_context->format();
+    format.setSwapInterval(Settings::values.use_vsync_new ? 1 : 0);
+    this->setFormat(format);
 
-    void resizeEvent(QResizeEvent* ev) override {
-        parent->OnClientAreaResized(ev->size().width(), ev->size().height());
-        parent->OnFramebufferSizeChanged();
-    }
+    context->setShareContext(shared_context);
+    context->setScreen(this->screen());
+    context->setFormat(format);
+    context->create();
 
-    void DisablePainting() {
-        do_painting = false;
-    }
-    void EnablePainting() {
-        do_painting = true;
-    }
+    LOG_WARNING(Frontend, "OpenGLWindow context format Interval {}",
+                context->format().swapInterval());
 
-private:
-    GRenderWindow* parent;
-    bool do_painting;
-};
+    LOG_WARNING(Frontend, "OpenGLWindow surface format interval {}", this->format().swapInterval());
+
+    setSurfaceType(QWindow::OpenGLSurface);
+
+    // TODO: One of these flags might be interesting: WA_OpaquePaintEvent, WA_NoBackground,
+    // WA_DontShowOnScreen, WA_DeleteOnClose
+}
+
+OpenGLWindow::~OpenGLWindow() {
+    context->doneCurrent();
+}
+
+void OpenGLWindow::Present() {
+    if (!isExposed())
+        return;
+    context->makeCurrent(this);
+    VideoCore::g_renderer->TryPresent(100);
+    context->swapBuffers(this);
+    auto f = context->versionFunctions<QOpenGLFunctions_3_3_Core>();
+    f->glFinish();
+    QWindow::requestUpdate();
+}
+
+bool OpenGLWindow::event(QEvent* event) {
+    switch (event->type()) {
+    case QEvent::UpdateRequest:
+        Present();
+        return true;
+    case QEvent::MouseButtonPress:
+    case QEvent::MouseButtonRelease:
+    case QEvent::MouseButtonDblClick:
+    case QEvent::MouseMove:
+    case QEvent::KeyPress:
+    case QEvent::KeyRelease:
+    case QEvent::FocusIn:
+    case QEvent::FocusOut:
+    case QEvent::FocusAboutToChange:
+    case QEvent::Enter:
+    case QEvent::Leave:
+    case QEvent::Wheel:
+    case QEvent::TabletMove:
+    case QEvent::TabletPress:
+    case QEvent::TabletRelease:
+    case QEvent::TabletEnterProximity:
+    case QEvent::TabletLeaveProximity:
+    case QEvent::TouchBegin:
+    case QEvent::TouchUpdate:
+    case QEvent::TouchEnd:
+    case QEvent::InputMethodQuery:
+    case QEvent::TouchCancel:
+        return QCoreApplication::sendEvent(event_handler, event);
+    case QEvent::Drop:
+        GetMainWindow()->DropAction(static_cast<QDropEvent*>(event));
+        return true;
+    case QEvent::DragResponse:
+    case QEvent::DragEnter:
+    case QEvent::DragLeave:
+    case QEvent::DragMove:
+        GetMainWindow()->AcceptDropEvent(static_cast<QDropEvent*>(event));
+        return true;
+    default:
+        return QWindow::event(event);
+    }
+}
+
+void OpenGLWindow::exposeEvent(QExposeEvent* event) {
+    QWindow::requestUpdate();
+    QWindow::exposeEvent(event);
+}
 
 GRenderWindow::GRenderWindow(QWidget* parent, EmuThread* emu_thread)
-    : QWidget(parent), child(nullptr), emu_thread(emu_thread) {
+    : QWidget(parent), emu_thread(emu_thread) {
 
     setWindowTitle(QStringLiteral("Citra %1 | %2-%3")
                        .arg(Common::g_build_name, Common::g_scm_branch, Common::g_scm_desc));
     setAttribute(Qt::WA_AcceptTouchEvents);
-
+    auto layout = new QHBoxLayout(this);
+    layout->setMargin(0);
+    setLayout(layout);
     InputCommon::Init();
 }
 
@@ -121,35 +196,12 @@ GRenderWindow::~GRenderWindow() {
     InputCommon::Shutdown();
 }
 
-void GRenderWindow::moveContext() {
-    DoneCurrent();
-
-    // If the thread started running, move the GL Context to the new thread. Otherwise, move it
-    // back.
-    auto thread = (QThread::currentThread() == qApp->thread() && emu_thread != nullptr)
-                      ? emu_thread
-                      : qApp->thread();
-    child->context()->moveToThread(thread);
-}
-
-void GRenderWindow::SwapBuffers() {
-    // In our multi-threaded QGLWidget use case we shouldn't need to call `makeCurrent`,
-    // since we never call `doneCurrent` in this thread.
-    // However:
-    // - The Qt debug runtime prints a bogus warning on the console if `makeCurrent` wasn't called
-    // since the last time `swapBuffers` was executed;
-    // - On macOS, if `makeCurrent` isn't called explicitely, resizing the buffer breaks.
-    child->makeCurrent();
-
-    child->swapBuffers();
-}
-
 void GRenderWindow::MakeCurrent() {
-    child->makeCurrent();
+    core_context->MakeCurrent();
 }
 
 void GRenderWindow::DoneCurrent() {
-    child->doneCurrent();
+    core_context->DoneCurrent();
 }
 
 void GRenderWindow::PollEvents() {}
@@ -163,8 +215,8 @@ void GRenderWindow::OnFramebufferSizeChanged() {
     // Screen changes potentially incur a change in screen DPI, hence we should update the
     // framebuffer size
     const qreal pixel_ratio = windowPixelRatio();
-    const u32 width = child->QPaintDevice::width() * pixel_ratio;
-    const u32 height = child->QPaintDevice::height() * pixel_ratio;
+    const u32 width = this->width() * pixel_ratio;
+    const u32 height = this->height() * pixel_ratio;
     UpdateCurrentFramebufferLayout(width, height);
 }
 
@@ -194,8 +246,7 @@ QByteArray GRenderWindow::saveGeometry() {
 }
 
 qreal GRenderWindow::windowPixelRatio() const {
-    // windowHandle() might not be accessible until the window is displayed to screen.
-    return windowHandle() ? windowHandle()->screen()->devicePixelRatio() : 1.0f;
+    return devicePixelRatio();
 }
 
 std::pair<u32, u32> GRenderWindow::ScaleTouch(const QPointF pos) const {
@@ -279,15 +330,19 @@ void GRenderWindow::TouchEndEvent() {
 }
 
 bool GRenderWindow::event(QEvent* event) {
-    if (event->type() == QEvent::TouchBegin) {
+    switch (event->type()) {
+    case QEvent::TouchBegin:
         TouchBeginEvent(static_cast<QTouchEvent*>(event));
         return true;
-    } else if (event->type() == QEvent::TouchUpdate) {
+    case QEvent::TouchUpdate:
         TouchUpdateEvent(static_cast<QTouchEvent*>(event));
         return true;
-    } else if (event->type() == QEvent::TouchEnd || event->type() == QEvent::TouchCancel) {
+    case QEvent::TouchEnd:
+    case QEvent::TouchCancel:
         TouchEndEvent();
         return true;
+    default:
+        break;
     }
 
     return QWidget::event(event);
@@ -298,45 +353,36 @@ void GRenderWindow::focusOutEvent(QFocusEvent* event) {
     InputCommon::GetKeyboard()->ReleaseAllKeys();
 }
 
-void GRenderWindow::OnClientAreaResized(u32 width, u32 height) {
-    NotifyClientAreaSizeChanged(std::make_pair(width, height));
+void GRenderWindow::resizeEvent(QResizeEvent* event) {
+    QWidget::resizeEvent(event);
+    OnFramebufferSizeChanged();
 }
 
 void GRenderWindow::InitRenderTarget() {
-    if (child) {
-        delete child;
-    }
+    ReleaseRenderTarget();
 
-    if (layout()) {
-        delete layout();
-    }
-
-    // TODO: One of these flags might be interesting: WA_OpaquePaintEvent, WA_NoBackground,
-    // WA_DontShowOnScreen, WA_DeleteOnClose
-    QGLFormat fmt;
-    fmt.setVersion(3, 3);
-    fmt.setProfile(QGLFormat::CoreProfile);
-    fmt.setSwapInterval(Settings::values.vsync_enabled);
-
-    // Requests a forward-compatible context, which is required to get a 3.2+ context on OS X
-    fmt.setOption(QGL::NoDeprecatedFunctions);
-
-    child = new GGLWidgetInternal(fmt, this);
-    QBoxLayout* layout = new QHBoxLayout(this);
+    GMainWindow* parent = GetMainWindow();
+    QWindow* parent_win_handle = parent ? parent->windowHandle() : nullptr;
+    child_window = new OpenGLWindow(parent_win_handle, this, QOpenGLContext::globalShareContext());
+    child_window->create();
+    child_widget = createWindowContainer(child_window, this);
+    child_widget->resize(Core::kScreenTopWidth, Core::kScreenTopHeight + Core::kScreenBottomHeight);
+    layout()->addWidget(child_widget);
 
+    core_context = CreateSharedContext();
     resize(Core::kScreenTopWidth, Core::kScreenTopHeight + Core::kScreenBottomHeight);
-    layout->addWidget(child);
-    layout->setMargin(0);
-    setLayout(layout);
-
     OnMinimalClientAreaChangeRequest(GetActiveConfig().min_client_area_size);
-
-    OnFramebufferSizeChanged();
-    NotifyClientAreaSizeChanged(std::pair<unsigned, unsigned>(child->width(), child->height()));
-
     BackupGeometry();
 }
 
+void GRenderWindow::ReleaseRenderTarget() {
+    if (child_widget) {
+        layout()->removeWidget(child_widget);
+        delete child_widget;
+        child_widget = nullptr;
+    }
+}
+
 void GRenderWindow::CaptureScreenshot(u32 res_scale, const QString& screenshot_path) {
     if (res_scale == 0)
         res_scale = VideoCore::GetResolutionScaleFactor();
@@ -361,18 +407,40 @@ void GRenderWindow::OnMinimalClientAreaChangeRequest(std::pair<u32, u32> minimal
 
 void GRenderWindow::OnEmulationStarting(EmuThread* emu_thread) {
     this->emu_thread = emu_thread;
-    child->DisablePainting();
 }
 
 void GRenderWindow::OnEmulationStopping() {
     emu_thread = nullptr;
-    child->EnablePainting();
 }
 
 void GRenderWindow::showEvent(QShowEvent* event) {
     QWidget::showEvent(event);
-
-    // windowHandle() is not initialized until the Window is shown, so we connect it here.
-    connect(windowHandle(), &QWindow::screenChanged, this, &GRenderWindow::OnFramebufferSizeChanged,
-            Qt::UniqueConnection);
+}
+
+std::unique_ptr<Frontend::GraphicsContext> GRenderWindow::CreateSharedContext() const {
+    return std::make_unique<GLContext>(QOpenGLContext::globalShareContext());
+}
+
+GLContext::GLContext(QOpenGLContext* shared_context)
+    : context(new QOpenGLContext(shared_context->parent())),
+      surface(new QOffscreenSurface(nullptr)) {
+
+    // disable vsync for any shared contexts
+    auto format = shared_context->format();
+    format.setSwapInterval(0);
+
+    context->setShareContext(shared_context);
+    context->setFormat(format);
+    context->create();
+    surface->setParent(shared_context->parent());
+    surface->setFormat(format);
+    surface->create();
+}
+
+void GLContext::MakeCurrent() {
+    context->makeCurrent(surface);
+}
+
+void GLContext::DoneCurrent() {
+    context->doneCurrent();
 }

src/citra_qt/bootmanager.h

@@ -7,9 +7,9 @@
 #include <atomic>
 #include <condition_variable>
 #include <mutex>
-#include <QGLWidget>
-#include <QImage>
 #include <QThread>
+#include <QWidget>
+#include <QWindow>
 #include "common/thread.h"
 #include "core/core.h"
 #include "core/frontend/emu_window.h"
@@ -17,16 +17,30 @@
 class QKeyEvent;
 class QScreen;
 class QTouchEvent;
+class QOffscreenSurface;
+class QOpenGLContext;
 
-class GGLWidgetInternal;
 class GMainWindow;
 class GRenderWindow;
 
+class GLContext : public Frontend::GraphicsContext {
+public:
+    explicit GLContext(QOpenGLContext* shared_context);
+
+    void MakeCurrent() override;
+
+    void DoneCurrent() override;
+
+private:
+    QOpenGLContext* context;
+    QOffscreenSurface* surface;
+};
+
 class EmuThread final : public QThread {
     Q_OBJECT
 
 public:
-    explicit EmuThread(GRenderWindow* render_window);
+    explicit EmuThread(Frontend::GraphicsContext& context);
     ~EmuThread() override;
 
     /**
@@ -80,7 +94,7 @@ private:
     std::mutex running_mutex;
     std::condition_variable running_cv;
 
-    GRenderWindow* render_window;
+    Frontend::GraphicsContext& core_context;
 
 signals:
     /**
@@ -104,6 +118,24 @@ signals:
     void ErrorThrown(Core::System::ResultStatus, std::string);
 };
 
+class OpenGLWindow : public QWindow {
+    Q_OBJECT
+public:
+    explicit OpenGLWindow(QWindow* parent, QWidget* event_handler, QOpenGLContext* shared_context);
+
+    ~OpenGLWindow();
+
+    void Present();
+
+protected:
+    bool event(QEvent* event) override;
+    void exposeEvent(QExposeEvent* event) override;
+
+private:
+    QOpenGLContext* context;
+    QWidget* event_handler;
+};
+
 class GRenderWindow : public QWidget, public Frontend::EmuWindow {
     Q_OBJECT
 
@@ -111,11 +143,11 @@ public:
     GRenderWindow(QWidget* parent, EmuThread* emu_thread);
     ~GRenderWindow() override;
 
-    // EmuWindow implementation
-    void SwapBuffers() override;
+    // EmuWindow implementation.
     void MakeCurrent() override;
     void DoneCurrent() override;
     void PollEvents() override;
+    std::unique_ptr<Frontend::GraphicsContext> CreateSharedContext() const override;
 
     void BackupGeometry();
     void RestoreGeometry();
@@ -126,6 +158,8 @@ public:
 
     void closeEvent(QCloseEvent* event) override;
 
+    void resizeEvent(QResizeEvent* event) override;
+
     void keyPressEvent(QKeyEvent* event) override;
     void keyReleaseEvent(QKeyEvent* event) override;
 
@@ -137,14 +171,14 @@ public:
 
     void focusOutEvent(QFocusEvent* event) override;
 
-    void OnClientAreaResized(u32 width, u32 height);
-
     void InitRenderTarget();
 
+    /// Destroy the previous run's child_widget which should also destroy the child_window
+    void ReleaseRenderTarget();
+
     void CaptureScreenshot(u32 res_scale, const QString& screenshot_path);
 
 public slots:
-    void moveContext(); // overridden
 
     void OnEmulationStarting(EmuThread* emu_thread);
     void OnEmulationStopping();
@@ -162,10 +196,18 @@ private:
 
     void OnMinimalClientAreaChangeRequest(std::pair<u32, u32> minimal_size) override;
 
-    GGLWidgetInternal* child;
+    std::unique_ptr<GraphicsContext> core_context;
 
     QByteArray geometry;
 
+    /// Native window handle that backs this presentation widget
+    QWindow* child_window = nullptr;
+
+    /// In order to embed the window into GRenderWindow, you need to use createWindowContainer to
+    /// put the child_window into a widget then add it to the layout. This child_widget can be
+    /// parented to GRenderWindow and use Qt's lifetime system
+    QWidget* child_widget = nullptr;
+
     EmuThread* emu_thread;
 
     /// Temporary storage of the screenshot taken

src/citra_qt/configuration/config.cpp

@@ -430,9 +430,9 @@ void Config::ReadRendererValues() {
     Settings::values.shaders_accurate_mul =
         ReadSetting(QStringLiteral("shaders_accurate_mul"), false).toBool();
     Settings::values.use_shader_jit = ReadSetting(QStringLiteral("use_shader_jit"), true).toBool();
+    Settings::values.use_vsync_new = ReadSetting(QStringLiteral("use_vsync_new"), true).toBool();
     Settings::values.resolution_factor =
         static_cast<u16>(ReadSetting(QStringLiteral("resolution_factor"), 1).toInt());
-    Settings::values.vsync_enabled = ReadSetting(QStringLiteral("vsync_enabled"), false).toBool();
     Settings::values.use_frame_limit =
         ReadSetting(QStringLiteral("use_frame_limit"), true).toBool();
     Settings::values.frame_limit = ReadSetting(QStringLiteral("frame_limit"), 100).toInt();
@@ -859,8 +859,8 @@ void Config::SaveRendererValues() {
     WriteSetting(QStringLiteral("shaders_accurate_mul"), Settings::values.shaders_accurate_mul,
                  false);
     WriteSetting(QStringLiteral("use_shader_jit"), Settings::values.use_shader_jit, true);
+    WriteSetting(QStringLiteral("use_vsync_new"), Settings::values.use_vsync_new, true);
     WriteSetting(QStringLiteral("resolution_factor"), Settings::values.resolution_factor, 1);
-    WriteSetting(QStringLiteral("vsync_enabled"), Settings::values.vsync_enabled, false);
     WriteSetting(QStringLiteral("use_frame_limit"), Settings::values.use_frame_limit, true);
     WriteSetting(QStringLiteral("frame_limit"), Settings::values.frame_limit, 100);
 

src/citra_qt/configuration/configure_graphics.cpp

@@ -18,6 +18,8 @@ ConfigureGraphics::ConfigureGraphics(QWidget* parent)
     SetConfiguration();
 
     ui->hw_renderer_group->setEnabled(ui->toggle_hw_renderer->isChecked());
+    ui->toggle_vsync_new->setEnabled(!Core::System::GetInstance().IsPoweredOn());
+
     connect(ui->toggle_hw_renderer, &QCheckBox::toggled, this, [this] {
         auto checked = ui->toggle_hw_renderer->isChecked();
         ui->hw_renderer_group->setEnabled(checked);
@@ -46,6 +48,7 @@ void ConfigureGraphics::SetConfiguration() {
     ui->toggle_hw_shader->setChecked(Settings::values.use_hw_shader);
     ui->toggle_accurate_mul->setChecked(Settings::values.shaders_accurate_mul);
     ui->toggle_shader_jit->setChecked(Settings::values.use_shader_jit);
+    ui->toggle_vsync_new->setChecked(Settings::values.use_vsync_new);
 }
 
 void ConfigureGraphics::ApplyConfiguration() {
@@ -53,6 +56,7 @@ void ConfigureGraphics::ApplyConfiguration() {
     Settings::values.use_hw_shader = ui->toggle_hw_shader->isChecked();
     Settings::values.shaders_accurate_mul = ui->toggle_accurate_mul->isChecked();
     Settings::values.use_shader_jit = ui->toggle_shader_jit->isChecked();
+    Settings::values.use_vsync_new = ui->toggle_vsync_new->isChecked();
 }
 
 void ConfigureGraphics::RetranslateUI() {

src/citra_qt/configuration/configure_graphics.ui

@@ -105,6 +105,25 @@
      </layout>
     </widget>
    </item>
+   <item>
+    <widget class="QGroupBox" name="groupBox">
+     <property name="title">
+      <string>Advanced</string>
+     </property>
+     <layout class="QVBoxLayout" name="verticalLayout_2">
+      <item>
+       <widget class="QCheckBox" name="toggle_vsync_new">
+        <property name="toolTip">
+         <string>VSync prevents the screen from tearing, but some graphics cards have lower performance with VSync enabled. Keep it enabled if you don't notice a performance difference.</string>
+        </property>
+        <property name="text">
+         <string>Enable VSync</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item>
     <spacer name="verticalSpacer">
      <property name="orientation">

src/citra_qt/main.cpp

@@ -5,12 +5,11 @@
 #include <clocale>
 #include <memory>
 #include <thread>
-#include <glad/glad.h>
-#define QT_NO_OPENGL
 #include <QDesktopWidget>
 #include <QFileDialog>
 #include <QFutureWatcher>
 #include <QMessageBox>
+#include <QOpenGLFunctions_3_3_Core>
 #include <QSysInfo>
 #include <QtConcurrent/QtConcurrentRun>
 #include <QtGui>
@@ -72,6 +71,7 @@
 #include "core/file_sys/archive_extsavedata.h"
 #include "core/file_sys/archive_source_sd_savedata.h"
 #include "core/frontend/applets/default_applets.h"
+#include "core/frontend/scope_acquire_context.h"
 #include "core/gdbstub/gdbstub.h"
 #include "core/hle/service/fs/archive.h"
 #include "core/hle/service/nfc/nfc.h"
@@ -768,13 +768,14 @@ bool GMainWindow::LoadROM(const QString& filename) {
         ShutdownGame();
 
     render_window->InitRenderTarget();
-    render_window->MakeCurrent();
+
+    Frontend::ScopeAcquireContext scope(*render_window);
 
     const QString below_gl33_title = tr("OpenGL 3.3 Unsupported");
     const QString below_gl33_message = tr("Your GPU may not support OpenGL 3.3, or you do not "
                                           "have the latest graphics driver.");
 
-    if (!gladLoadGL()) {
+    if (!QOpenGLContext::globalShareContext()->versionFunctions<QOpenGLFunctions_3_3_Core>()) {
         QMessageBox::critical(this, below_gl33_title, below_gl33_message);
         return false;
     }
@@ -893,9 +894,8 @@ void GMainWindow::BootGame(const QString& filename) {
         return;
 
     // Create and start the emulation thread
-    emu_thread = std::make_unique<EmuThread>(render_window);
+    emu_thread = std::make_unique<EmuThread>(*render_window);
     emit EmulationStarting(emu_thread.get());
-    render_window->moveContext();
     emu_thread->start();
 
     connect(render_window, &GRenderWindow::Closed, this, &GMainWindow::OnStopGame);
@@ -1019,6 +1019,9 @@ void GMainWindow::ShutdownGame() {
     UpdateWindowTitle();
 
     game_path.clear();
+
+    // When closing the game, destroy the GLWindow to clear the context after the game is closed
+    render_window->ReleaseRenderTarget();
 }
 
 void GMainWindow::StoreRecentFile(const QString& filename) {
@@ -1869,14 +1872,33 @@ void GMainWindow::closeEvent(QCloseEvent* event) {
     QWidget::closeEvent(event);
 }
 
-static bool IsSingleFileDropEvent(QDropEvent* event) {
-    const QMimeData* mimeData = event->mimeData();
-    return mimeData->hasUrls() && mimeData->urls().length() == 1;
+static bool IsSingleFileDropEvent(const QMimeData* mime) {
+    return mime->hasUrls() && mime->urls().length() == 1;
 }
 
-void GMainWindow::dropEvent(QDropEvent* event) {
-    if (!IsSingleFileDropEvent(event)) {
-        return;
+static const std::array<std::string, 8> AcceptedExtensions = {"cci",  "3ds", "cxi", "bin",
+                                                              "3dsx", "app", "elf", "axf"};
+
+static bool IsCorrectFileExtension(const QMimeData* mime) {
+    const QString& filename = mime->urls().at(0).toLocalFile();
+    return std::find(AcceptedExtensions.begin(), AcceptedExtensions.end(),
+                     QFileInfo(filename).suffix().toStdString()) != AcceptedExtensions.end();
+}
+
+static bool IsAcceptableDropEvent(QDropEvent* event) {
+    return IsSingleFileDropEvent(event->mimeData()) && IsCorrectFileExtension(event->mimeData());
+}
+
+void GMainWindow::AcceptDropEvent(QDropEvent* event) {
+    if (IsAcceptableDropEvent(event)) {
+        event->setDropAction(Qt::DropAction::LinkAction);
+        event->accept();
+    }
+}
+
+bool GMainWindow::DropAction(QDropEvent* event) {
+    if (!IsAcceptableDropEvent(event)) {
+        return false;
     }
 
     const QMimeData* mime_data = event->mimeData();
@@ -1891,16 +1913,19 @@ void GMainWindow::dropEvent(QDropEvent* event) {
             BootGame(filename);
         }
     }
+    return true;
+}
+
+void GMainWindow::dropEvent(QDropEvent* event) {
+    DropAction(event);
 }
 
 void GMainWindow::dragEnterEvent(QDragEnterEvent* event) {
-    if (IsSingleFileDropEvent(event)) {
-        event->acceptProposedAction();
-    }
+    AcceptDropEvent(event);
 }
 
 void GMainWindow::dragMoveEvent(QDragMoveEvent* event) {
-    event->acceptProposedAction();
+    AcceptDropEvent(event);
 }
 
 bool GMainWindow::ConfirmChangeGame() {
@@ -2050,11 +2075,20 @@ int main(int argc, char* argv[]) {
     QCoreApplication::setOrganizationName("Citra team");
     QCoreApplication::setApplicationName("Citra");
 
+    QSurfaceFormat format;
+    format.setVersion(3, 3);
+    format.setProfile(QSurfaceFormat::CoreProfile);
+    format.setSwapInterval(0);
+    // TODO: expose a setting for buffer value (ie default/single/double/triple)
+    format.setSwapBehavior(QSurfaceFormat::DefaultSwapBehavior);
+    QSurfaceFormat::setDefaultFormat(format);
+
 #ifdef __APPLE__
     std::string bin_path = FileUtil::GetBundleDirectory() + DIR_SEP + "..";
     chdir(bin_path.c_str());
 #endif
-
+    QCoreApplication::setAttribute(Qt::AA_DontCheckOpenGLContextThreadAffinity);
+    QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
     QApplication app(argc, argv);
 
     // Qt changes the locale and causes issues in float conversion using std::to_string() when

src/citra_qt/main.h

@@ -41,6 +41,7 @@ class QProgressBar;
 class RegistersWidget;
 class Updater;
 class WaitTreeWidget;
+
 namespace DiscordRPC {
 class DiscordInterface;
 }
@@ -69,8 +70,12 @@ public:
     GameList* game_list;
     std::unique_ptr<DiscordRPC::DiscordInterface> discord_rpc;
 
+    bool DropAction(QDropEvent* event);
+    void AcceptDropEvent(QDropEvent* event);
+
 public slots:
     void OnAppFocusStateChanged(Qt::ApplicationState state);
+
 signals:
 
     /**
@@ -78,8 +83,8 @@ signals:
      * about to start. At this time, the core system emulation has been initialized, and all
      * emulation handles and memory should be valid.
      *
-     * @param emu_thread Pointer to the newly created EmuThread (to be used by widgets that need to
-     *      access/change emulation state).
+     * @param emu_thread Pointer to the newly created EmuThread (to be used by widgets that need
+     * to access/change emulation state).
      */
     void EmulationStarting(EmuThread* emu_thread);