donutbreakdownchart.cpp Example File | Qt Charts 5.12.12

- Qt 5.12
- Qt Charts
- Donut Chart Breakdown Example
- donutbreakdownchart.cpp Example File
- Qt Charts | Commercial or GPLv3

# donutbreakdownchart.cpp Example File

donutbreakdown/donutbreakdownchart.cpp

     /****************************************************************************
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     ** Copyright (C) 2016 The Qt Company Ltd.
     ** Contact: https://www.qt.io/licensing/
     **
     ** 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));
                 }
             }
         }
     }