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.
**
** $QT_BEGIN_LICENSE:GPL$
** 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);
    }
}

© 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.