Problem with QChart

franco.amato

I need to plot a simple chart that basically is composed by points connected by lines so I though to use a mixture of the QScatterSeries and QLineSeries. What I would like to achieve is shown in the following graph (the blue line only):

But I got this instead:

The first point should have the Y value of 1.2 but in the second graph it seems to be 0. The X axis has no integer values because I don't need it, I just need to plot the Y value of some points corresponding to specific AOI names.
This is the code that draw the graphs:

void MainWindow::generatePointChartForAOI(const QString& aoiName, const std::vector<AOI>& aoiList)
{
    m_chart->removeAllSeries();
    m_chart->removeAxis(m_axisY);

    // Target metric type and metric name
    const QString targetMetricTypeName = "Time to First Fixation";
    const QString targetMetricName = "Mean";

    // Create a single series for the target metric
    QLineSeries* series = new QLineSeries();
    series->setName(targetMetricTypeName);

    // Create a QScatterSeries for the dots
    QScatterSeries* scatterSeries = new QScatterSeries();
    scatterSeries->setName(targetMetricTypeName + " (dots)"); // Optional: Set a name for the scatter series
    scatterSeries->setMarkerShape(QScatterSeries::MarkerShapeCircle); // Set the marker shape to a circle
    scatterSeries->setMarkerSize(10.0); // Adjust the marker size as needed

    QStringList categories;
    int aoiIndex = 0;
    for (const AOI& aoi : aoiList)
    {
        if (aoi.aoiName == aoiName)
        {
            continue;
        }

        // Find the target metric type
        auto itMetricType = std::find_if(aoi.metricTypes.begin(), aoi.metricTypes.end(),
                                         [&targetMetricTypeName](const MetricType& mt) {
                                             return mt.metricTypeName == targetMetricTypeName;
                                         });

        if (itMetricType != aoi.metricTypes.end())
        {
            // Find the target metric within the metric type
            auto itMetric = std::find_if(itMetricType->metrics.begin(), itMetricType->metrics.end(),
                                         [&targetMetricName](const Metric& m) {
                                             return m.descriptiveStat == targetMetricName;
                                         });

            if (itMetric != itMetricType->metrics.end())
            {
                bool ok;
                double metricValue = itMetric->value.toDouble(&ok);
                if (ok)
                {
                    series->append(aoiIndex, metricValue);
                    scatterSeries->append(aoiIndex, metricValue);
                    qDebug() << "Adding:" << metricValue; // Prints correctly the values
                }
                else
                {
                    qDebug() << "Failed to convert metric value to double:" << itMetric->value;
                }
            }
        }

        categories.append(aoi.aoiName);
        aoiIndex++;
    }
    m_chart->setTitle(aoiName);

    double minY = series->at(0).y();
    double maxY = minY;
    for (const QPointF& point : series->points())
    {
        maxY = qMax(maxY, point.y());
    }
    m_chart->addSeries(series);
    m_chart->addSeries(scatterSeries);

    m_axisY->setRange(0, maxY + 1);
    qDebug() << m_axisY->min() << m_axisY->max();
    m_axisX->append(categories);
    m_chart->addAxis(m_axisY, Qt::AlignLeft);
}

The values are correct, the first value prints 1.2
I did some initializations in the MainWindow ctor

MainWindow::MainWindow(QWidget* parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    connect(ui->loadFileButton, &QPushButton::clicked, this, &MainWindow::loadFile);
    connect(ui->expandPushButton, &QPushButton::clicked, this, &MainWindow::handleExpandButton);

    m_chart = new QChart;
    m_axisY = new QValueAxis();

    m_axisX = new QBarCategoryAxis();
    m_axisX->setTitleText("AOI Names");
    m_axisX->setLabelsAngle(-45);

    m_chart->addAxis(m_axisX, Qt::AlignBottom);
    m_chart->addAxis(m_axisY, Qt::AlignLeft);

    ui->chartView->setChart(m_chart);
    ui->chartView->setRenderHint(QPainter::Antialiasing);
}

The generatePointChartForAOI method is executed every time the user clicks on some items in a treeview.
I also noticed that at every call, the labels in the X axis are added to the labels of the previous call.
I tried also to remove the X axis at every call and add again but it didn't solve the problem

void MainWindow::generatePointChartForAOI(const QString& aoiName, const std::vector<AOI>& aoiList)
{
    m_chart->removeAllSeries();
    m_chart->removeAxis(m_axisX);

I also would like the x position of the points so stay in the middle of the AOI labels
I would like to have some help