donutbreakdownchart.cpp Example File

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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();
      foreach (QPieSlice *slice, breakdownSeries->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;
      foreach (QPieSlice *slice, m_mainSeries->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
      foreach (QAbstractSeries *series, series()) {
          foreach (QLegendMarker *marker, legend()->markers(series)) {
              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));
              }
          }
      }
  }