QChart in QGridLabel

[Creatorczyk]

Hi,
I would like to display three charts in a grid. For this purpose, I created the ChartManager class, but when I add a widget, the chart is not visible. Displaying the ChartManager is done throught the widget promotions. When I add a button, for example, it was visible, I checked.

How could I fix the code to make the chart visible?

File ChartManager.h

#ifndef CHARTMANAGER_H
#define CHARTMANAGER_H

#include <QGridLayout>
#include <QPushButton>
#include <QChartView>

#include "chart.h"

class ChartManager : public QGridLayout
{
public:
    ChartManager(QWidget *parent = nullptr);
};

#endif // CHARTMANAGER_H

File Chart Manager.cpp

#include "chartmanager.h"

ChartManager::ChartManager(QWidget *parent) : QGridLayout(parent)
{
    Chart *tempChart = new Chart();
    tempChart->setTitle("Temperature Chart");
    tempChart->legend()->hide();
    tempChart->setAnimationOptions(QChart::AllAnimations);
    QChartView tempChartView(tempChart);
    tempChartView.setRenderHint(QPainter::Antialiasing);
    addWidget(&tempChartView,0,0);
}

My charts are from example "dynamic spline"

Chart.h

#ifndef CHART_H
#define CHART_H

#include <QtCharts/QChart>
#include <QtCore/QTimer>

QT_CHARTS_BEGIN_NAMESPACE
class QSplineSeries;
class QValueAxis;
QT_CHARTS_END_NAMESPACE

QT_CHARTS_USE_NAMESPACE

class Chart: public QChart
{
    Q_OBJECT
public:
    Chart(QGraphicsItem *parent = nullptr, Qt::WindowFlags wFlags = nullptr);
    virtual ~Chart();

public slots:
    void handleTimeout();

private:
    QTimer m_timer;
    QSplineSeries *m_series;
    QStringList m_titles;
    QValueAxis *m_axisX;
    QValueAxis *m_axisY;
    qreal m_step;
    qreal m_x;
    qreal m_y;
};

#endif /* CHART_H */

Chart.cpp

#include "chart.h"
#include <QtCharts/QAbstractAxis>
#include <QtCharts/QSplineSeries>
#include <QtCharts/QValueAxis>
#include <QtCore/QRandomGenerator>
#include <QtCore/QDebug>

Chart::Chart(QGraphicsItem *parent, Qt::WindowFlags wFlags):
    QChart(QChart::ChartTypeCartesian, parent, wFlags),
    m_series(nullptr),
    m_axisX(new QValueAxis()),
    m_axisY(new QValueAxis()),
    m_step(0),
    m_x(5),
    m_y(1)
{
    QObject::connect(&m_timer, &QTimer::timeout, this, &Chart::handleTimeout);
    m_timer.setInterval(1000);

    m_series = new QSplineSeries(this);
    QPen green(Qt::red);
    green.setWidth(3);
    m_series->setPen(green);
    m_series->append(m_x, m_y);

    addSeries(m_series);

    addAxis(m_axisX,Qt::AlignBottom);
    addAxis(m_axisY,Qt::AlignLeft);
    m_series->attachAxis(m_axisX);
    m_series->attachAxis(m_axisY);
    m_axisX->setTickCount(5);
    m_axisX->setRange(0, 10);
    m_axisY->setRange(-5, 10);

    m_timer.start();
}

Chart::~Chart()
{

}

void Chart::handleTimeout()
{
    qreal x = plotArea().width() / m_axisX->tickCount();
    qreal y = (m_axisX->max() - m_axisX->min()) / m_axisX->tickCount();
    m_x += y;
    m_y = QRandomGenerator::global()->bounded(5) - 2.5;
    m_series->append(m_x, m_y);
    scroll(x, 0);
    if (m_x == 100.0)
        m_timer.stop();
}

[Pl45m4]

@Creatorczyk

Why you subclassed QGridLayout for your ChartManager?

[Creatorczyk]

@Pl45m4 Because I want create my own widget based on QGridLayout but showing charts

[Pl45m4]

@Creatorczyk said in QChart in QGridLabel:

my own widget

Subclassing QWidget would work better in your case. Make your ChartManager a QWidget, then assign a layout with your Charts

[mrjj]

Hi
You also have a Widget that will run out of scope and get deleted

#include "chartmanager.h"

ChartManager::ChartManager(QWidget *parent) : QGridLayout(parent)
{
    Chart *tempChart = new Chart();
    tempChart->setTitle("Temperature Chart");
    tempChart->legend()->hide();
    tempChart->setAnimationOptions(QChart::AllAnimations);

    QChartView tempChartView(tempChart); <<<<< this local vaiable and will be deleted at end of ctor

    tempChartView.setRenderHint(QPainter::Antialiasing);
    addWidget(&tempChartView,0,0);
}

So you should do
QChartView * tempChartView = new QChartView
to avoid this.

[Creatorczyk]

@mrjj Thanks, it's works