datasource.cpp Example File

openglseries/datasource.cpp
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 #include "datasource.h"
 #include <QtCore/QtMath>
 #include <QtCore/QRandomGenerator>

 QT_CHARTS_USE_NAMESPACE

 DataSource::DataSource(QObject *parent) :
     QObject(parent),
     m_index(-1)
 {
     generateData(0, 0, 0);
 }

 void DataSource::update(QAbstractSeries *series, int seriesIndex)
 {
     if (series) {
         QXYSeries *xySeries = static_cast<QXYSeries *>(series);
         const QVector<QVector<QPointF> > &seriesData = m_data.at(seriesIndex);
         if (seriesIndex == 0)
             m_index++;
         if (m_index > seriesData.count() - 1)
             m_index = 0;

         QVector<QPointF> points = seriesData.at(m_index);
         // Use replace instead of clear + append, it's optimized for performance
         xySeries->replace(points);
     }
 }

 void DataSource::handleSceneChanged()
 {
     m_dataUpdater.start();
 }

 void DataSource::updateAllSeries()
 {
     static int frameCount = 0;
     static QString labelText = QStringLiteral("FPS: %1");

     for (int i = 0; i < m_seriesList.size(); i++)
         update(m_seriesList[i], i);

     frameCount++;
     int elapsed = m_fpsTimer.elapsed();
     if (elapsed >= 1000) {
         elapsed = m_fpsTimer.restart();
         qreal fps = qreal(0.1 * int(10000.0 * (qreal(frameCount) / qreal(elapsed))));
         m_fpsLabel->setText(labelText.arg(QString::number(fps, 'f', 1)));
         m_fpsLabel->adjustSize();
         frameCount = 0;
     }
 }

 void DataSource::startUpdates(const QList<QXYSeries *> &seriesList, QLabel *fpsLabel)
 {
     m_seriesList = seriesList;
     m_fpsLabel = fpsLabel;

     m_dataUpdater.setInterval(0);
     m_dataUpdater.setSingleShot(true);
     QObject::connect(&m_dataUpdater, &QTimer::timeout,
                      this, &DataSource::updateAllSeries);

     m_fpsTimer.start();
     updateAllSeries();
 }

 void DataSource::generateData(int seriesCount, int rowCount, int colCount)
 {
     m_data.clear();

     qreal xAdjustment = 20.0 / (colCount * rowCount);
     qreal yMultiplier = 3.0 / qreal(seriesCount);

     // Append the new data depending on the type
     for (int k(0); k < seriesCount; k++) {
         QVector<QVector<QPointF> > seriesData;
         qreal height = qreal(k) * (10.0 / qreal(seriesCount)) + 0.3;
         for (int i(0); i < rowCount; i++) {
             QVector<QPointF> points;
             points.reserve(colCount);
             for (int j(0); j < colCount; j++) {
                 qreal x(0);
                 qreal y(0);
                 // data with sin + random component
                 y = height + (yMultiplier * qSin(M_PI / 50 * j)
                               + (yMultiplier * QRandomGenerator::global()->generateDouble()));
                 // 0.000001 added to make values logaxis compatible
                 x = 0.000001 + 20.0 * (qreal(j) / qreal(colCount)) + (xAdjustment * qreal(i));
                 points.append(QPointF(x, y));
             }
             seriesData.append(points);
         }
         m_data.append(seriesData);
     }
 }