window_singlethreaded.cpp Example File

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#include "window_singlethreaded.h" #include "cuberenderer.h" #include <QOpenGLContext> #include <QOpenGLFunctions> #include <QOpenGLFramebufferObject> #include <QOpenGLShaderProgram> #include <QOpenGLVertexArrayObject> #include <QOpenGLBuffer> #include <QOpenGLVertexArrayObject> #include <QOffscreenSurface> #include <QScreen> #include <QQmlEngine> #include <QQmlComponent> #include <QQuickItem> #include <QQuickWindow> #include <QQuickRenderControl> #include <QCoreApplication> class RenderControl : public QQuickRenderControl { public: RenderControl(QWindow *w) : m_window(w) { } QWindow *renderWindow(QPoint *offset) Q_DECL_OVERRIDE; private: QWindow *m_window; }; QWindow *RenderControl::renderWindow(QPoint *offset) { if (offset) *offset = QPoint(0, 0); return m_window; } WindowSingleThreaded::WindowSingleThreaded() : m_rootItem(0), m_fbo(0), m_quickInitialized(false), m_quickReady(false), m_dpr(0) { setSurfaceType(QSurface::OpenGLSurface); QSurfaceFormat format; // Qt Quick may need a depth and stencil buffer. Always make sure these are available. format.setDepthBufferSize(16); format.setStencilBufferSize(8); setFormat(format); m_context = new QOpenGLContext; m_context->setFormat(format); m_context->create(); m_offscreenSurface = new QOffscreenSurface; // Pass m_context->format(), not format. Format does not specify and color buffer // sizes, while the context, that has just been created, reports a format that has // these values filled in. Pass this to the offscreen surface to make sure it will be // compatible with the context's configuration. m_offscreenSurface->setFormat(m_context->format()); m_offscreenSurface->create(); m_cubeRenderer = new CubeRenderer(m_offscreenSurface); m_renderControl = new RenderControl(this); // Create a QQuickWindow that is associated with out render control. Note that this // window never gets created or shown, meaning that it will never get an underlying // native (platform) window. m_quickWindow = new QQuickWindow(m_renderControl); // Create a QML engine. m_qmlEngine = new QQmlEngine; if (!m_qmlEngine->incubationController()) m_qmlEngine->setIncubationController(m_quickWindow->incubationController()); // When Quick says there is a need to render, we will not render immediately. Instead, // a timer with a small interval is used to get better performance. m_updateTimer.setSingleShot(true); m_updateTimer.setInterval(5); connect(&m_updateTimer, &QTimer::timeout, this, &WindowSingleThreaded::render); // Now hook up the signals. For simplicy we don't differentiate between // renderRequested (only render is needed, no sync) and sceneChanged (polish and sync // is needed too). connect(m_quickWindow, &QQuickWindow::sceneGraphInitialized, this, &WindowSingleThreaded::createFbo); connect(m_quickWindow, &QQuickWindow::sceneGraphInvalidated, this, &WindowSingleThreaded::destroyFbo); connect(m_renderControl, &QQuickRenderControl::renderRequested, this, &WindowSingleThreaded::requestUpdate); connect(m_renderControl, &QQuickRenderControl::sceneChanged, this, &WindowSingleThreaded::requestUpdate); // Just recreating the FBO on resize is not sufficient, when moving between screens // with different devicePixelRatio the QWindow size may remain the same but the FBO // dimension is to change regardless. connect(this, &QWindow::screenChanged, this, &WindowSingleThreaded::handleScreenChange); } WindowSingleThreaded::~WindowSingleThreaded() { // Make sure the context is current while doing cleanup. Note that we use the // offscreen surface here because passing 'this' at this point is not safe: the // underlying platform window may already be destroyed. To avoid all the trouble, use // another surface that is valid for sure. m_context->makeCurrent(m_offscreenSurface); // Delete the render control first since it will free the scenegraph resources. // Destroy the QQuickWindow only afterwards. delete m_renderControl; delete m_qmlComponent; delete m_quickWindow; delete m_qmlEngine; delete m_fbo; m_context->doneCurrent(); delete m_cubeRenderer; delete m_offscreenSurface; delete m_context; } void WindowSingleThreaded::createFbo() { // The scene graph has been initialized. It is now time to create an FBO and associate // it with the QQuickWindow. m_dpr = devicePixelRatio(); m_fbo = new QOpenGLFramebufferObject(size() * m_dpr, QOpenGLFramebufferObject::CombinedDepthStencil); m_quickWindow->setRenderTarget(m_fbo); } void WindowSingleThreaded::destroyFbo() { delete m_fbo; m_fbo = 0; } void WindowSingleThreaded::render() { if (!m_context->makeCurrent(m_offscreenSurface)) return; // Polish, synchronize and render the next frame (into our fbo). In this example // everything happens on the same thread and therefore all three steps are performed // in succession from here. In a threaded setup the render() call would happen on a // separate thread. m_renderControl->polishItems(); m_renderControl->sync(); m_renderControl->render(); m_quickWindow->resetOpenGLState(); QOpenGLFramebufferObject::bindDefault(); m_context->functions()->glFlush(); m_quickReady = true; // Get something onto the screen. m_cubeRenderer->render(this, m_context, m_quickReady ? m_fbo->texture() : 0); } void WindowSingleThreaded::requestUpdate() { if (!m_updateTimer.isActive()) m_updateTimer.start(); } void WindowSingleThreaded::run() { disconnect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowSingleThreaded::run); if (m_qmlComponent->isError()) { const QList<QQmlError> errorList = m_qmlComponent->errors(); for (const QQmlError &error : errorList) qWarning() << error.url() << error.line() << error; return; } QObject *rootObject = m_qmlComponent->create(); if (m_qmlComponent->isError()) { const QList<QQmlError> errorList = m_qmlComponent->errors(); for (const QQmlError &error : errorList) qWarning() << error.url() << error.line() << error; return; } m_rootItem = qobject_cast<QQuickItem *>(rootObject); if (!m_rootItem) { qWarning("run: Not a QQuickItem"); delete rootObject; return; } // The root item is ready. Associate it with the window. m_rootItem->setParentItem(m_quickWindow->contentItem()); // Update item and rendering related geometries. updateSizes(); // Initialize the render control and our OpenGL resources. m_context->makeCurrent(m_offscreenSurface); m_renderControl->initialize(m_context); m_quickInitialized = true; } void WindowSingleThreaded::updateSizes() { // Behave like SizeRootObjectToView. m_rootItem->setWidth(width()); m_rootItem->setHeight(height()); m_quickWindow->setGeometry(0, 0, width(), height()); m_cubeRenderer->resize(width(), height()); } void WindowSingleThreaded::startQuick(const QString &filename) { m_qmlComponent = new QQmlComponent(m_qmlEngine, QUrl(filename)); if (m_qmlComponent->isLoading()) connect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowSingleThreaded::run); else run(); } void WindowSingleThreaded::exposeEvent(QExposeEvent *) { if (isExposed()) { if (!m_quickInitialized) { m_cubeRenderer->render(this, m_context, m_quickReady ? m_fbo->texture() : 0); startQuick(QStringLiteral("qrc:/rendercontrol/demo.qml")); } } } void WindowSingleThreaded::resizeFbo() { if (m_rootItem && m_context->makeCurrent(m_offscreenSurface)) { delete m_fbo; createFbo(); m_context->doneCurrent(); updateSizes(); render(); } } void WindowSingleThreaded::resizeEvent(QResizeEvent *) { // If this is a resize after the scene is up and running, recreate the fbo and the // Quick item and scene. if (m_fbo && m_fbo->size() != size() * devicePixelRatio()) resizeFbo(); } void WindowSingleThreaded::handleScreenChange() { if (m_dpr != devicePixelRatio()) resizeFbo(); } void WindowSingleThreaded::mousePressEvent(QMouseEvent *e) { // Use the constructor taking localPos and screenPos. That puts localPos into the // event's localPos and windowPos, and screenPos into the event's screenPos. This way // the windowPos in e is ignored and is replaced by localPos. This is necessary // because QQuickWindow thinks of itself as a top-level window always. QMouseEvent mappedEvent(e->type(), e->localPos(), e->screenPos(), e->button(), e->buttons(), e->modifiers()); QCoreApplication::sendEvent(m_quickWindow, &mappedEvent); } void WindowSingleThreaded::mouseReleaseEvent(QMouseEvent *e) { QMouseEvent mappedEvent(e->type(), e->localPos(), e->screenPos(), e->button(), e->buttons(), e->modifiers()); QCoreApplication::sendEvent(m_quickWindow, &mappedEvent); }

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