Qt Documentation

Contents

Custom Chart Example

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Customizing Charts

We begin by creating a simple line series and a chart object.

    QLineSeries *series = new QLineSeries();
    *series << QPointF(0, 6) << QPointF(9, 4) << QPointF(15, 20) << QPointF(25, 12) << QPointF(29, 26);
    QChart *chart = new QChart();
    chart->legend()->hide();
    chart->addSeries(series);

First we customize the series and the chart's title and background.

    // Customize series
    QPen pen(QRgb(0xfdb157));
    pen.setWidth(5);
    series->setPen(pen);

    // Customize chart title
    QFont font;
    font.setPixelSize(18);
    chart->setTitleFont(font);
    chart->setTitleBrush(QBrush(Qt::white));
    chart->setTitle("Customchart example");

    // Customize chart background
    QLinearGradient backgroundGradient;
    backgroundGradient.setStart(QPointF(0, 0));
    backgroundGradient.setFinalStop(QPointF(0, 1));
    backgroundGradient.setColorAt(0.0, QRgb(0xd2d0d1));
    backgroundGradient.setColorAt(1.0, QRgb(0x4c4547));
    backgroundGradient.setCoordinateMode(QGradient::ObjectBoundingMode);
    chart->setBackgroundBrush(backgroundGradient);

    // Customize plot area background
    QLinearGradient plotAreaGradient;
    plotAreaGradient.setStart(QPointF(0, 1));
    plotAreaGradient.setFinalStop(QPointF(1, 0));
    plotAreaGradient.setColorAt(0.0, QRgb(0x555555));
    plotAreaGradient.setColorAt(1.0, QRgb(0x55aa55));
    plotAreaGradient.setCoordinateMode(QGradient::ObjectBoundingMode);
    chart->setPlotAreaBackgroundBrush(plotAreaGradient);
    chart->setPlotAreaBackgroundVisible(true);

Then we customize the axes.

    QCategoryAxis *axisX = new QCategoryAxis();
    QCategoryAxis *axisY = new QCategoryAxis();

    // Customize axis label font
    QFont labelsFont;
    labelsFont.setPixelSize(12);
    axisX->setLabelsFont(labelsFont);
    axisY->setLabelsFont(labelsFont);

    // Customize axis colors
    QPen axisPen(QRgb(0xd18952));
    axisPen.setWidth(2);
    axisX->setLinePen(axisPen);
    axisY->setLinePen(axisPen);

    // Customize axis label colors
    QBrush axisBrush(Qt::white);
    axisX->setLabelsBrush(axisBrush);
    axisY->setLabelsBrush(axisBrush);

    // Customize grid lines and shades
    axisX->setGridLineVisible(false);
    axisY->setGridLineVisible(false);
    axisY->setShadesPen(Qt::NoPen);
    axisY->setShadesBrush(QBrush(QColor(0x99, 0xcc, 0xcc, 0x55)));
    axisY->setShadesVisible(true);

Then the axis label values and ranges. Once the axes are ready, we set them to be used by the chart.

    axisX->append("low", 10);
    axisX->append("optimal", 20);
    axisX->append("high", 30);
    axisX->setRange(0, 30);

    axisY->append("slow", 10);
    axisY->append("med", 20);
    axisY->append("fast", 30);
    axisY->setRange(0, 30);

    chart->setAxisX(axisX, series);
    chart->setAxisY(axisY, series);

Finally, we create a view containing the chart.

    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);

Now we are ready to show the chart on a main window.

    QMainWindow window;
    window.setCentralWidget(chartView);
    window.resize(400, 300);
    window.show();

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