Qt 5.9 | Qt Charts | Donut Chart Breakdown Example | donutbreakdownchart.cpp Example File

Qt 5.9.3 Reference Documentation

# donutbreakdownchart.cpp Example File

donutbreakdown/donutbreakdownchart.cpp

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      ** Contact: https://www.qt.io/licensing/
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      ** This file is part of the Qt Charts module of the Qt Toolkit.
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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));
                  }
              }
          }
      }