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Viewing changes to src/plugin/libreofficetoolkit-qml-plugin/renderengine.cpp

New method of multithreaded rendering.

Approved by Stefano Verzegnassi, Ubuntu Phone Apps Jenkins Bot.

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src/plugin/libreofficetoolkit-qml-plugin/renderengine.cpp
 
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#include "renderengine.h"
 
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#include <QtConcurrent/QtConcurrent>
 
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#include <QThread>
 
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RenderEngine* RenderEngine::s_instance = nullptr;
 
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RenderEngine::RenderEngine():
 
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    QObject(nullptr),
 
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    m_activeTaskCount(0)
 
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{
 
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    int itc = QThread::idealThreadCount();
 
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    m_idealThreadCount = itc == -1 ? DefaultIdealThreadCount : itc;
 
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}
 
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void RenderEngine::enqueueTask(const QSharedPointer<LODocument>& doc, const QRect& area, int id)
 
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{
 
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    Q_ASSERT(doc != nullptr);
 
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    m_queue.enqueue(EngineTask(doc, area, id));
 
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    doNextTask();
 
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}
 
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void RenderEngine::dequeueTask(int id)
 
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{
 
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    for (int i = 0; i < m_queue.size(); i++)
 
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        if (m_queue.at(i).id == id) {
 
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            m_queue.removeAt(i);
 
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            break;
 
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        }
 
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}
 
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void RenderEngine::internalRenderCallback(int id, QImage img)
 
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{
 
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    m_activeTaskCount--;
 
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    Q_EMIT renderFinished(id, img);
 
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    doNextTask();
 
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}
 
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void RenderEngine::doNextTask()
 
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{
 
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#ifdef DEBUG_VERBOSE
 
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    qDebug() << " ---- doNextTask" << m_activeTaskCount << m_queue.count();
 
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#endif
 
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    if (m_activeTaskCount >= m_idealThreadCount || !m_queue.count())
 
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        return;
 
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    m_activeTaskCount++;
 
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    auto task = m_queue.dequeue();
 
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    QtConcurrent::run( [=] {
 
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        QImage img = task.document->paintTile(task.area.size(), task.area);
 
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        QMetaObject::invokeMethod(this, "internalRenderCallback", Q_ARG(int, task.id), Q_ARG(QImage, img));
 
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    });
 
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}