donutbreakdownchart.cpp Example File

donutbreakdown/donutbreakdownchart.cpp
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 #include "donutbreakdownchart.h"
 #include "mainslice.h"
 #include <QtCharts/QPieSlice>
 #include <QtCharts/QPieLegendMarker>

 QT_CHARTS_USE_NAMESPACE

 DonutBreakdownChart::DonutBreakdownChart(QGraphicsItem *parent, Qt::WindowFlags wFlags)
     : QChart(QChart::ChartTypeCartesian, parent, wFlags)
 {
     // create the series for main center pie
     m_mainSeries = new QPieSeries();
     m_mainSeries->setPieSize(0.7);
     QChart::addSeries(m_mainSeries);
 }

 void DonutBreakdownChart::addBreakdownSeries(QPieSeries *breakdownSeries, QColor color)
 {
     QFont font("Arial", 8);

     // add breakdown series as a slice to center pie
     MainSlice *mainSlice = new MainSlice(breakdownSeries);
     mainSlice->setName(breakdownSeries->name());
     mainSlice->setValue(breakdownSeries->sum());
     m_mainSeries->append(mainSlice);

     // customize the slice
     mainSlice->setBrush(color);
     mainSlice->setLabelVisible();
     mainSlice->setLabelColor(Qt::white);
     mainSlice->setLabelPosition(QPieSlice::LabelInsideHorizontal);
     mainSlice->setLabelFont(font);

     // position and customize the breakdown series
     breakdownSeries->setPieSize(0.8);
     breakdownSeries->setHoleSize(0.7);
     breakdownSeries->setLabelsVisible();
     const auto slices = breakdownSeries->slices();
     for (QPieSlice *slice : slices) {
         color = color.lighter(115);
         slice->setBrush(color);
         slice->setLabelFont(font);
     }

     // add the series to the chart
     QChart::addSeries(breakdownSeries);

     // recalculate breakdown donut segments
     recalculateAngles();

     // update customize legend markers
     updateLegendMarkers();
 }

 void DonutBreakdownChart::recalculateAngles()
 {
     qreal angle = 0;
     const auto slices = m_mainSeries->slices();
     for (QPieSlice *slice : slices) {
         QPieSeries *breakdownSeries = qobject_cast<MainSlice *>(slice)->breakdownSeries();
         breakdownSeries->setPieStartAngle(angle);
         angle += slice->percentage() * 360.0; // full pie is 360.0
         breakdownSeries->setPieEndAngle(angle);
     }
 }

 void DonutBreakdownChart::updateLegendMarkers()
 {
     // go through all markers
     const auto allseries = series();
     for (QAbstractSeries *series : allseries) {
         const auto markers = legend()->markers(series);
         for (QLegendMarker *marker : markers) {
             QPieLegendMarker *pieMarker = qobject_cast<QPieLegendMarker *>(marker);
             if (series == m_mainSeries) {
                 // hide markers from main series
                 pieMarker->setVisible(false);
             } else {
                 // modify markers from breakdown series
                 pieMarker->setLabel(QString("%1 %2%")
                                     .arg(pieMarker->slice()->label())
                                     .arg(pieMarker->slice()->percentage() * 100, 0, 'f', 2));
                 pieMarker->setFont(QFont("Arial", 8));
             }
         }
     }
 }