datasource.cpp Example File

  /****************************************************************************
  **
  ** 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.
  **
  ** $QT_BEGIN_LICENSE:GPL$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
  ** Software or, alternatively, in accordance with the terms contained in
  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see https://www.qt.io/terms-conditions. For further
  ** information use the contact form at https://www.qt.io/contact-us.
  **
  ** GNU General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU
  ** General Public License version 3 or (at your option) any later version
  ** approved by the KDE Free Qt Foundation. The licenses are as published by
  ** the Free Software Foundation and appearing in the file LICENSE.GPL3
  ** included in the packaging of this file. Please review the following
  ** information to ensure the GNU General Public License requirements will
  ** be met: https://www.gnu.org/licenses/gpl-3.0.html.
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/

  #include "datasource.h"
  #include <QtCharts/QXYSeries>
  #include <QtCharts/QAreaSeries>
  #include <QtQuick/QQuickView>
  #include <QtQuick/QQuickItem>
  #include <QtCore/QDebug>
  #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
      foreach (QVector<QPointF> row, m_data)
          row.clear();
      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(3.14159265358979 / 50 * j) + 0.5 + (qreal) rand() / (qreal) RAND_MAX;
                  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);
      }
  }