datasource.cpp Example File | Qt Charts 5.12.8

- Qt 5.12
- Qt Charts
- Qml Oscilloscope
- datasource.cpp Example File
- Qt Charts | Commercial or GPLv3

# datasource.cpp Example File

qmloscilloscope/datasource.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2016 The Qt Company Ltd.
     ** Contact: https://www.qt.io/licensing/
     **
     ** This file is part of the Qt Charts module of the Qt Toolkit.
     **
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     ** the Free Software Foundation and appearing in the file LICENSE.GPL3
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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);
         }
     }