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);
 }