Change from QOpenGLWidget to QWindow

While QOpenGLWidget sounds like a good idea, it has issues which are
harder to debug due to how Qt manages the context behind the scenes. We
could probably work around any of these issues over time, but its
probably easier to do it ourselves with a QWindow directly.

Plus using QWindow + createWindowContainer is the easiest to use
configuration for Qt + Vulkan so this is probably much better in the
long run.

src/citra_qt/bootmanager.cpp

@@ -8,6 +8,7 @@
 #include <QOffscreenSurface>
 #include <QOpenGLContext>
 #include <QOpenGLFunctions>
+#include <QOpenGLWindow>
 #include <QScreen>
 #include <QWindow>
 #include <fmt/format.h>
@@ -79,13 +80,61 @@ void EmuThread::run() {
     MicroProfileOnThreadExit();
 #endif
 }
+OpenGLWindow::OpenGLWindow(QWindow* parent, QOpenGLContext* shared_context)
+    : QWindow(parent), context(new QOpenGLContext(shared_context->parent())) {
+    context->setShareContext(shared_context);
+    context->setScreen(this->screen());
+    context->setFormat(shared_context->format());
+    context->create();
+
+    setSurfaceType(QWindow::OpenGLSurface);
+
+    // TODO: One of these flags might be interesting: WA_OpaquePaintEvent, WA_NoBackground,
+    // WA_DontShowOnScreen, WA_DeleteOnClose
+
+    // We set the WindowTransparnentForInput flag to let qt pass the processing through this QWindow
+    // through the event stack up to the parent QWidget and then up to the GRenderWindow grandparent
+    // that handles the event
+    setFlags(Qt::WindowTransparentForInput);
+}
+
+OpenGLWindow::~OpenGLWindow() {
+    context->doneCurrent();
+}
+
+void OpenGLWindow::Present() {
+    if (!isExposed())
+        return;
+    context->makeCurrent(this);
+    VideoCore::g_renderer->TryPresent(100);
+    context->swapBuffers(this);
+    QWindow::requestUpdate();
+}
+
+bool OpenGLWindow::event(QEvent* event) {
+    switch (event->type()) {
+    case QEvent::UpdateRequest:
+        Present();
+        return true;
+    default:
+        return QWindow::event(event);
+    }
+}
+
+void OpenGLWindow::exposeEvent(QExposeEvent* event) {
+    QWindow::requestUpdate();
+    QWindow::exposeEvent(event);
+}
 
 GRenderWindow::GRenderWindow(QWidget* parent, EmuThread* emu_thread)
-    : QOpenGLWidget(parent), 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();
 }
 
@@ -247,23 +296,31 @@ void GRenderWindow::focusOutEvent(QFocusEvent* event) {
 }
 
 void GRenderWindow::resizeEvent(QResizeEvent* event) {
-    QOpenGLWidget::resizeEvent(event);
+    child_widget->resize(event->size());
+    QWidget::resizeEvent(event);
     OnFramebufferSizeChanged();
 }
 
 void GRenderWindow::InitRenderTarget() {
-    // TODO: One of these flags might be interesting: WA_OpaquePaintEvent, WA_NoBackground,
-    // WA_DontShowOnScreen, WA_DeleteOnClose
+    // Destroy the previous run's child_widget which should also destroy the child_window
+    if (child_widget) {
+        layout()->removeWidget(child_widget);
+        delete child_widget;
+    }
+
+    child_window =
+        new OpenGLWindow(QWidget::window()->windowHandle(), 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);
     OnMinimalClientAreaChangeRequest(GetActiveConfig().min_client_area_size);
     BackupGeometry();
 }
 
-void GRenderWindow::initializeGL() {
-    context()->format().setSwapInterval(1);
-}
-
 void GRenderWindow::CaptureScreenshot(u32 res_scale, const QString& screenshot_path) {
     if (res_scale == 0)
         res_scale = VideoCore::GetResolutionScaleFactor();
@@ -294,11 +351,6 @@ void GRenderWindow::OnEmulationStopping() {
     emu_thread = nullptr;
 }
 
-void GRenderWindow::paintGL() {
-    VideoCore::g_renderer->TryPresent(100);
-    update();
-}
-
 void GRenderWindow::showEvent(QShowEvent* event) {
     QWidget::showEvent(event);
 }

src/citra_qt/bootmanager.h

@@ -7,8 +7,9 @@
 #include <atomic>
 #include <condition_variable>
 #include <mutex>
-#include <QOpenGLWidget>
 #include <QThread>
+#include <QWidget>
+#include <QWindow>
 #include "common/thread.h"
 #include "core/core.h"
 #include "core/frontend/emu_window.h"
@@ -117,7 +118,25 @@ signals:
     void ErrorThrown(Core::System::ResultStatus, std::string);
 };
 
-class GRenderWindow : public QOpenGLWidget, public Frontend::EmuWindow {
+class OpenGLWindow : public QWindow {
+    Q_OBJECT
+public:
+    explicit OpenGLWindow(QWindow* parent, QOpenGLContext* shared_context);
+
+    ~OpenGLWindow();
+
+    void Present();
+
+protected:
+    bool event(QEvent* event) override;
+
+    void exposeEvent(QExposeEvent* event) override;
+
+private:
+    QOpenGLContext* context;
+};
+
+class GRenderWindow : public QWidget, public Frontend::EmuWindow {
     Q_OBJECT
 
 public:
@@ -130,9 +149,6 @@ public:
     void PollEvents() override;
     std::unique_ptr<Frontend::GraphicsContext> CreateSharedContext() const override;
 
-    void initializeGL() override;
-    void paintGL() override;
-
     void BackupGeometry();
     void RestoreGeometry();
     void restoreGeometry(const QByteArray& geometry); // overridden
@@ -181,6 +197,14 @@ private:
 
     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/core/frontend/emu_window.h

@@ -31,7 +31,7 @@ public:
     /**
      * Recreate the presentation objects attached to this frame with the new specified width/height
      */
-    virtual void ReloadPresentFrame(Frontend::Frame* frame, u32 height, u32 width) = 0;
+    virtual void ReloadPresentFrame(Frontend::Frame* frame, u32 width, u32 height) = 0;
 
     /**
      * Render thread calls this to get an available frame to present

src/video_core/renderer_opengl/gl_resource_manager.cpp

@@ -29,6 +29,7 @@ void OGLRenderbuffer::Release() {
 
     MICROPROFILE_SCOPE(OpenGL_ResourceDeletion);
     glDeleteRenderbuffers(1, &handle);
+    OpenGLState::GetCurState().ResetRenderbuffer(handle).Apply();
     handle = 0;
 }
 

src/video_core/renderer_opengl/gl_state.cpp

@@ -428,4 +428,11 @@ OpenGLState& OpenGLState::ResetFramebuffer(GLuint handle) {
     return *this;
 }
 
+OpenGLState& OpenGLState::ResetRenderbuffer(GLuint handle) {
+    if (renderbuffer == handle) {
+        renderbuffer = 0;
+    }
+    return *this;
+}
+
 } // namespace OpenGL

src/video_core/renderer_opengl/gl_state.h

@@ -144,7 +144,7 @@ public:
 
     std::array<bool, 2> clip_distance; // GL_CLIP_DISTANCE
 
-    GLuint renderbuffer;
+    GLuint renderbuffer; // GL_RENDERBUFFER_BINDING
 
     OpenGLState();
 
@@ -164,6 +164,7 @@ public:
     OpenGLState& ResetBuffer(GLuint handle);
     OpenGLState& ResetVertexArray(GLuint handle);
     OpenGLState& ResetFramebuffer(GLuint handle);
+    OpenGLState& ResetRenderbuffer(GLuint handle);
 
 private:
     static OpenGLState cur_state;

src/video_core/renderer_opengl/renderer_opengl.cpp

@@ -11,6 +11,7 @@
 #include <memory>
 #include <mutex>
 #include <glad/glad.h>
+#include <queue>
 #include "common/assert.h"
 #include "common/bit_field.h"
 #include "common/logging/log.h"
@@ -59,13 +60,13 @@ public:
     std::condition_variable free_cv;
     std::condition_variable present_cv;
     std::array<Frontend::Frame, SWAP_CHAIN_SIZE> swap_chain{};
-    std::deque<Frontend::Frame*> free_queue{};
+    std::queue<Frontend::Frame*> free_queue{};
     std::deque<Frontend::Frame*> present_queue{};
     Frontend::Frame* previous_frame = nullptr;
 
     OGLTextureMailbox() {
         for (auto& frame : swap_chain) {
-            free_queue.push_back(&frame);
+            free_queue.push(&frame);
         }
     }
 
@@ -73,7 +74,7 @@ public:
         // lock the mutex and clear out the present and free_queues and notify any people who are
         // blocked to prevent deadlock on shutdown
         std::scoped_lock lock(swap_chain_lock);
-        free_queue.clear();
+        std::queue<Frontend::Frame*>().swap(free_queue);
         present_queue.clear();
         free_cv.notify_all();
         present_cv.notify_all();
@@ -137,7 +138,7 @@ public:
         }
 
         Frontend::Frame* frame = free_queue.front();
-        free_queue.pop_front();
+        free_queue.pop();
         return frame;
     }
 
@@ -153,13 +154,13 @@ public:
         present_cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),
                             [&] { return !present_queue.empty(); });
         if (present_queue.empty()) {
-            // timed out waiting for a frame to draw so return nullptr
+            // timed out waiting for a frame to draw so return the previous frame
             return previous_frame;
         }
 
         // free the previous frame and add it back to the free queue
         if (previous_frame) {
-            free_queue.push_back(previous_frame);
+            free_queue.push(previous_frame);
             free_cv.notify_one();
         }
 
@@ -168,9 +169,9 @@ public:
         present_queue.pop_front();
         // remove all old entries from the present queue and move them back to the free_queue
         for (auto f : present_queue) {
-            free_queue.push_back(f);
-            free_cv.notify_one();
+            free_queue.push(f);
         }
+        free_cv.notify_one();
         present_queue.clear();
         previous_frame = frame;
         return frame;