datasource.cpp Example File

qmloscilloscope/datasource.cpp
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 #include "datasource.h"
 #include <QtCharts/QXYSeries>
 #include <QtCharts/QAreaSeries>
 #include <QtQuick/QQuickView>
 #include <QtQuick/QQuickItem>
 #include <QtCore/QDebug>
 #include <QtCore/QRandomGenerator>
 #include <QtCore/QtMath>

 QT_CHARTS_USE_NAMESPACE

 Q_DECLARE_METATYPE(QAbstractSeries *)
 Q_DECLARE_METATYPE(QAbstractAxis *)

 DataSource::DataSource(QQuickView *appViewer, QObject *parent) :
     QObject(parent),
     m_appViewer(appViewer),
     m_index(-1)
 {
     qRegisterMetaType<QAbstractSeries*>();
     qRegisterMetaType<QAbstractAxis*>();

     generateData(0, 5, 1024);
 }

 void DataSource::update(QAbstractSeries *series)
 {
     if (series) {
         QXYSeries *xySeries = static_cast<QXYSeries *>(series);
         m_index++;
         if (m_index > m_data.count() - 1)
             m_index = 0;

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

 void DataSource::generateData(int type, int rowCount, int colCount)
 {
     // Remove previous data
     m_data.clear();

     // Append the new data depending on the type
     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);
             switch (type) {
             case 0:
                 // data with sin + random component
                 y = qSin(M_PI / 50 * j) + 0.5 + QRandomGenerator::global()->generateDouble();
                 x = j;
                 break;
             case 1:
                 // linear data
                 x = j;
                 y = (qreal) i / 10;
                 break;
             default:
                 // unknown, do nothing
                 break;
             }
             points.append(QPointF(x, y));
         }
         m_data.append(points);
     }
 }