QChart -problem with time axis X

Creatorczyk

Hi,

I did a class with my own QChart. I would like incoming messages to be displayed in a chart. I would like the X axis to show the time when value was added. I also made the chart in such a way that it was dynamic. Unfortunately , when it is displayed, the X axis is not shown to me and I do not know what it may be coused by. I used timer as a messaging simulator.

My .cpp file

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

Chart::Chart(const QColor color, const qreal minYRange, const qreal maxYRange, const QString &units, QGraphicsItem *parent, Qt::WindowFlags wFlags):
    QChart(QChart::ChartTypeCartesian, parent, wFlags),
    series(nullptr),
    axisX(new QDateTimeAxis()),
    axisY(new QValueAxis()),
    m_step(0),
    m_x(9),
    m_y(1)
{
    QObject::connect(&m_timer, &QTimer::timeout, this, &Chart::handleTimeout);
    m_timer.setInterval(1000);

    visualConfig();

    series = new QSplineSeries(this);
    QPen green(color);
    green.setWidth(3);
    series->setPen(green);

    series->append(QDateTime::currentDateTime().toMSecsSinceEpoch(), m_y);

    addSeries(series);

    addAxis(axisX,Qt::AlignBottom);
    addAxis(axisY,Qt::AlignLeft);
    series->attachAxis(axisX);
    series->attachAxis(axisY);
    axisX->setTickCount(12);
    axisX->setRange(QDateTime::currentDateTime(), QDateTime::currentDateTime());
    axisX->setFormat("h mm");


    axisY->setRange(minYRange, maxYRange);
    axisY->setTickCount(5);
    axisY->setTitleText(units);

    m_timer.start();
}

Chart::~Chart()
{

}

void Chart::handleTimeout()
{
    QPointF last_sample = series->at(series->count()-1);
    qreal last_time = last_sample.x();

    QDateTime actual_time = QDateTime::currentDateTime();
    m_y = QRandomGenerator::global()->bounded(10, 50);
    series->append(actual_time.toMSecsSinceEpoch(), m_y);

    qreal time_difference = actual_time.toMSecsSinceEpoch() - last_time;
    scroll(time_difference, 0);
}

void Chart::visualConfig()
{
    setMargins(QMargins(0,0,0,0));
    legend()->hide();
    setAnimationOptions(QChart::AllAnimations);

    setBackgroundVisible(false);
    axisX->setGridLineVisible(false);
    axisY->setGridLineVisible(false);

    QFont labelsFont;
    labelsFont.setPixelSize(10);
    axisX->setLabelsFont(labelsFont);
    axisY->setLabelsFont(labelsFont);

    axisX->setLabelsBrush(Qt::white);
    axisY->setLabelsBrush(Qt::white);
}

JonB

@Creatorczyk
I don't know. Did you try removing lines of code till it did work? Does the Y axis show? Is axisX->setLabelsBrush(Qt::white); by any chance writing on a while background? In axisX->setRange(QDateTime::currentDateTime(), QDateTime::currentDateTime()); is it a good idea to set a range where the minimum & maximum are equal?