1 files changed, 454 insertions, 0 deletions
diff --git a/examples/quick/rendercontrol/rendercontrol_opengl/window_multithreaded.cpp b/examples/quick/rendercontrol/rendercontrol_opengl/window_multithreaded.cpp
new file mode 100644
index 0000000000..01d6b8b5b2
--- /dev/null
+++ b/examples/quick/rendercontrol/rendercontrol_opengl/window_multithreaded.cpp
@@ -0,0 +1,454 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "window_multithreaded.h"
+#include "cuberenderer.h"
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+#include <QOpenGLFramebufferObject>
+#include <QOpenGLShaderProgram>
+#include <QOpenGLVertexArrayObject>
+#include <QOpenGLBuffer>
+#include <QOpenGLVertexArrayObject>
+#include <QOffscreenSurface>
+#include <QQmlEngine>
+#include <QQmlComponent>
+#include <QQuickItem>
+#include <QQuickWindow>
+#include <QQuickRenderControl>
+#include <QCoreApplication>
+
+/*
+  This implementation runs the Qt Quick scenegraph's sync and render phases on a
+  separate, dedicated thread.  Rendering the cube using our custom OpenGL engine
+  happens on that thread as well.  This is similar to the built-in threaded
+  render loop, but does not support all the features. There is no support for
+  getting Animators running on the render thread for example.
+
+  We choose to use QObject's event mechanism to communicate with the QObject
+  living on the render thread. An alternative would be to subclass QThread and
+  reimplement run() with a custom event handling approach, like
+  QSGThreadedRenderLoop does. That would potentially lead to better results but
+  is also more complex.
+*/
+
+static const QEvent::Type INIT = QEvent::Type(QEvent::User + 1);
+static const QEvent::Type RENDER = QEvent::Type(QEvent::User + 2);
+static const QEvent::Type RESIZE = QEvent::Type(QEvent::User + 3);
+static const QEvent::Type STOP = QEvent::Type(QEvent::User + 4);
+
+static const QEvent::Type UPDATE = QEvent::Type(QEvent::User + 5);
+
+QuickRenderer::QuickRenderer()
+    : m_context(nullptr),
+      m_surface(nullptr),
+      m_fbo(nullptr),
+      m_window(nullptr),
+      m_quickWindow(nullptr),
+      m_renderControl(nullptr),
+      m_cubeRenderer(nullptr),
+      m_quit(false)
+{
+}
+
+void QuickRenderer::requestInit()
+{
+    QCoreApplication::postEvent(this, new QEvent(INIT));
+}
+
+void QuickRenderer::requestRender()
+{
+    QCoreApplication::postEvent(this, new QEvent(RENDER));
+}
+
+void QuickRenderer::requestResize()
+{
+    QCoreApplication::postEvent(this, new QEvent(RESIZE));
+}
+
+void QuickRenderer::requestStop()
+{
+    QCoreApplication::postEvent(this, new QEvent(STOP));
+}
+
+bool QuickRenderer::event(QEvent *e)
+{
+    QMutexLocker lock(&m_mutex);
+
+    switch (int(e->type())) {
+    case INIT:
+        init();
+        return true;
+    case RENDER:
+        render(&lock);
+        return true;
+    case RESIZE:
+        if (m_cubeRenderer)
+            m_cubeRenderer->resize(m_window->width(), m_window->height());
+        return true;
+    case STOP:
+        cleanup();
+        return true;
+    default:
+        return QObject::event(e);
+    }
+}
+
+void QuickRenderer::init()
+{
+    m_context->makeCurrent(m_surface);
+
+    // Pass our offscreen surface to the cube renderer just so that it will
+    // have something is can make current during cleanup. QOffscreenSurface,
+    // just like QWindow, must always be created on the gui thread (as it might
+    // be backed by an actual QWindow).
+    m_cubeRenderer = new CubeRenderer(m_surface);
+    m_cubeRenderer->resize(m_window->width(), m_window->height());
+
+    m_renderControl->initialize(m_context);
+}
+
+void QuickRenderer::cleanup()
+{
+    m_context->makeCurrent(m_surface);
+
+    m_renderControl->invalidate();
+
+    delete m_fbo;
+    m_fbo = nullptr;
+
+    delete m_cubeRenderer;
+    m_cubeRenderer = nullptr;
+
+    m_context->doneCurrent();
+    m_context->moveToThread(QCoreApplication::instance()->thread());
+
+    m_cond.wakeOne();
+}
+
+void QuickRenderer::ensureFbo()
+{
+    if (m_fbo && m_fbo->size() != m_window->size() * m_window->devicePixelRatio()) {
+        delete m_fbo;
+        m_fbo = nullptr;
+    }
+
+    if (!m_fbo) {
+        m_fbo = new QOpenGLFramebufferObject(m_window->size() * m_window->devicePixelRatio(),
+                                             QOpenGLFramebufferObject::CombinedDepthStencil);
+        m_quickWindow->setRenderTarget(m_fbo);
+    }
+}
+
+void QuickRenderer::render(QMutexLocker *lock)
+{
+    Q_ASSERT(QThread::currentThread() != m_window->thread());
+
+    if (!m_context->makeCurrent(m_surface)) {
+        qWarning("Failed to make context current on render thread");
+        return;
+    }
+
+    ensureFbo();
+
+    // Synchronization and rendering happens here on the render thread.
+    m_renderControl->sync();
+
+    // The gui thread can now continue.
+    m_cond.wakeOne();
+    lock->unlock();
+
+    // Meanwhile on this thread continue with the actual rendering (into the FBO first).
+    m_renderControl->render();
+    m_context->functions()->glFlush();
+
+    // The cube renderer uses its own context, no need to bother with the state here.
+
+    // Get something onto the screen using our custom OpenGL engine.
+    QMutexLocker quitLock(&m_quitMutex);
+    if (!m_quit)
+        m_cubeRenderer->render(m_window, m_context, m_fbo->texture());
+}
+
+void QuickRenderer::aboutToQuit()
+{
+    QMutexLocker lock(&m_quitMutex);
+    m_quit = true;
+}
+
+class RenderControl : public QQuickRenderControl
+{
+public:
+    RenderControl(QWindow *w) : m_window(w) { }
+    QWindow *renderWindow(QPoint *offset) override;
+
+private:
+    QWindow *m_window;
+};
+
+WindowMultiThreaded::WindowMultiThreaded()
+    : m_qmlComponent(nullptr),
+      m_rootItem(nullptr),
+      m_quickInitialized(false),
+      m_psrRequested(false)
+{
+    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_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());
+
+    m_quickRenderer = new QuickRenderer;
+    m_quickRenderer->setContext(m_context);
+
+    // These live on the gui thread. Just give access to them on the render thread.
+    m_quickRenderer->setSurface(m_offscreenSurface);
+    m_quickRenderer->setWindow(this);
+    m_quickRenderer->setQuickWindow(m_quickWindow);
+    m_quickRenderer->setRenderControl(m_renderControl);
+
+    m_quickRendererThread = new QThread;
+
+    // Notify the render control that some scenegraph internals have to live on
+    // m_quickRenderThread.
+    m_renderControl->prepareThread(m_quickRendererThread);
+
+    // The QOpenGLContext and the QObject representing the rendering logic on
+    // the render thread must live on that thread.
+    m_context->moveToThread(m_quickRendererThread);
+    m_quickRenderer->moveToThread(m_quickRendererThread);
+
+    m_quickRendererThread->start();
+
+    // 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_renderControl, &QQuickRenderControl::renderRequested, this, &WindowMultiThreaded::requestUpdate);
+    connect(m_renderControl, &QQuickRenderControl::sceneChanged, this, &WindowMultiThreaded::requestUpdate);
+}
+
+WindowMultiThreaded::~WindowMultiThreaded()
+{
+    // Release resources and move the context ownership back to this thread.
+    m_quickRenderer->mutex()->lock();
+    m_quickRenderer->requestStop();
+    m_quickRenderer->cond()->wait(m_quickRenderer->mutex());
+    m_quickRenderer->mutex()->unlock();
+
+    m_quickRendererThread->quit();
+    m_quickRendererThread->wait();
+
+    delete m_renderControl;
+    delete m_qmlComponent;
+    delete m_quickWindow;
+    delete m_qmlEngine;
+
+    delete m_offscreenSurface;
+    delete m_context;
+}
+
+void WindowMultiThreaded::requestUpdate()
+{
+    if (m_quickInitialized && !m_psrRequested) {
+        m_psrRequested = true;
+        QCoreApplication::postEvent(this, new QEvent(UPDATE));
+    }
+}
+
+bool WindowMultiThreaded::event(QEvent *e)
+{
+    if (e->type() == UPDATE) {
+        polishSyncAndRender();
+        m_psrRequested = false;
+        return true;
+    } else if (e->type() == QEvent::Close) {
+        // Avoid rendering on the render thread when the window is about to
+        // close. Once a QWindow is closed, the underlying platform window will
+        // go away, even though the QWindow instance itself is still
+        // valid. Operations like swapBuffers() are futile and only result in
+        // warnings afterwards. Prevent this.
+        m_quickRenderer->aboutToQuit();
+    }
+    return QWindow::event(e);
+}
+
+void WindowMultiThreaded::polishSyncAndRender()
+{
+    Q_ASSERT(QThread::currentThread() == thread());
+
+    // Polishing happens on the gui thread.
+    m_renderControl->polishItems();
+    // Sync happens on the render thread with the gui thread (this one) blocked.
+    QMutexLocker lock(m_quickRenderer->mutex());
+    m_quickRenderer->requestRender();
+    // Wait until sync is complete.
+    m_quickRenderer->cond()->wait(m_quickRenderer->mutex());
+    // Rendering happens on the render thread without blocking the gui (main)
+    // thread. This is good because the blocking swap (waiting for vsync)
+    // happens on the render thread, not blocking other work.
+}
+
+void WindowMultiThreaded::run()
+{
+    disconnect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowMultiThreaded::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();
+
+    m_quickInitialized = true;
+
+    // Initialize the render thread and perform the first polish/sync/render.
+    m_quickRenderer->requestInit();
+    polishSyncAndRender();
+}
+
+void WindowMultiThreaded::updateSizes()
+{
+    // Behave like SizeRootObjectToView.
+    m_rootItem->setWidth(width());
+    m_rootItem->setHeight(height());
+
+    m_quickWindow->setGeometry(0, 0, width(), height());
+}
+
+void WindowMultiThreaded::startQuick(const QString &filename)
+{
+    m_qmlComponent = new QQmlComponent(m_qmlEngine, QUrl(filename));
+    if (m_qmlComponent->isLoading())
+        connect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowMultiThreaded::run);
+    else
+        run();
+}
+
+void WindowMultiThreaded::exposeEvent(QExposeEvent *)
+{
+    if (isExposed()) {
+        if (!m_quickInitialized)
+            startQuick(QStringLiteral("qrc:/rendercontrol/demo.qml"));
+    }
+}
+
+void WindowMultiThreaded::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_rootItem) {
+        updateSizes();
+        m_quickRenderer->requestResize();
+        polishSyncAndRender();
+    }
+}
+
+void WindowMultiThreaded::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 WindowMultiThreaded::mouseReleaseEvent(QMouseEvent *e)
+{
+    QMouseEvent mappedEvent(e->type(), e->localPos(), e->screenPos(), e->button(), e->buttons(), e->modifiers());
+    QCoreApplication::sendEvent(m_quickWindow, &mappedEvent);
+}