diff options
author | Laszlo Agocs <laszlo.agocs@theqtcompany.com> | 2014-11-25 11:38:46 +0100 |
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committer | Laszlo Agocs <laszlo.agocs@theqtcompany.com> | 2014-12-12 12:19:14 +0100 |
commit | 6179550a0ca761bfabd4f6c67103f5397a306df0 (patch) | |
tree | eaf4a12431769a77ff3fed7945d1d0bf37144fcd /examples/quick/rendercontrol/window_multithreaded.cpp | |
parent | 2a6f6eee104ef66e4e236fa82fe71bb77f151ee8 (diff) |
Support threading with QQuickRenderControl
Reorganize the rendercontrol example to demonstrate both the single
and multi threaded approaches.
A small helper function is introduced to the QQuickRenderControl API:
The QSGRenderContext has to live on the render thread. Previously there
was no way for applications to move it to the desired thread. This is
now possible.
Pass --threaded to the rendercontrol example to use a separate render thread.
[ChangeLog][QtQuick] QQuickRenderControl can now be used to render the Qt Quick
scene on a dedicated render thread, similarly to how the built-in threaded render
loop operates.
Task-number: QTBUG-42813
Change-Id: I01c3b2ffca8a174d9d2c267a51f2e484ed7b34b3
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>
Diffstat (limited to 'examples/quick/rendercontrol/window_multithreaded.cpp')
-rw-r--r-- | examples/quick/rendercontrol/window_multithreaded.cpp | 423 |
1 files changed, 423 insertions, 0 deletions
diff --git a/examples/quick/rendercontrol/window_multithreaded.cpp b/examples/quick/rendercontrol/window_multithreaded.cpp new file mode 100644 index 0000000000..b59b0f59da --- /dev/null +++ b/examples/quick/rendercontrol/window_multithreaded.cpp @@ -0,0 +1,423 @@ +/**************************************************************************** +** +** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/legal +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** 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 Digia Plc and its Subsidiary(-ies) 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_fbo(0), + m_cubeRenderer(0), + 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); + + m_cubeRenderer = new CubeRenderer; + 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 = 0; + + delete m_cubeRenderer; + m_cubeRenderer = 0; + + 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 = 0; + } + + 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(); + + // 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; +} + +WindowMultiThreaded::WindowMultiThreaded() + : m_rootItem(0), + 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 QQuickRenderControl(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, SIGNAL(statusChanged(QQmlComponent::Status)), this, SLOT(run())); + + if (m_qmlComponent->isError()) { + QList<QQmlError> errorList = m_qmlComponent->errors(); + foreach (const QQmlError &error, errorList) + qWarning() << error.url() << error.line() << error; + return; + } + + QObject *rootObject = m_qmlComponent->create(); + if (m_qmlComponent->isError()) { + QList<QQmlError> errorList = m_qmlComponent->errors(); + foreach (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); +} |