Qt 5.9 | Qt Charts | Legend Example | mainwidget.cpp Example File

Qt 5.9.9 Reference Documentation

# mainwidget.cpp Example File

legend/mainwidget.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 "mainwidget.h"
      #include <QtCharts/QChart>
      #include <QtCharts/QChartView>
      #include <QtWidgets/QPushButton>
      #include <QtWidgets/QLabel>
      #include <QtCore/QDebug>
      #include <QtCharts/QBarSet>
      #include <QtCharts/QBarSeries>
      #include <QtCharts/QLegend>
      #include <QtWidgets/QFormLayout>

      QT_CHARTS_USE_NAMESPACE

      MainWidget::MainWidget(QWidget *parent) :
          QWidget(parent)
      {
          // Create buttons for ui
          m_buttonLayout = new QGridLayout();
          QPushButton *detachLegendButton = new QPushButton("Toggle attached");
          connect(detachLegendButton, &QPushButton::clicked, this, &MainWidget::toggleAttached);
          m_buttonLayout->addWidget(detachLegendButton, 0, 0);

          QPushButton *addSetButton = new QPushButton("add barset");
          connect(addSetButton, &QPushButton::clicked, this, &MainWidget::addBarset);
          m_buttonLayout->addWidget(addSetButton, 2, 0);
          QPushButton *removeBarsetButton = new QPushButton("remove barset");
          connect(removeBarsetButton, &QPushButton::clicked, this, &MainWidget::removeBarset);
          m_buttonLayout->addWidget(removeBarsetButton, 3, 0);

          QPushButton *alignButton = new QPushButton("Align (Bottom)");
          connect(alignButton, &QPushButton::clicked, this, &MainWidget::setLegendAlignment);
          m_buttonLayout->addWidget(alignButton, 4, 0);

          QPushButton *boldButton = new QPushButton("Toggle bold");
          connect(boldButton, &QPushButton::clicked, this, &MainWidget::toggleBold);
          m_buttonLayout->addWidget(boldButton, 8, 0);

          QPushButton *italicButton = new QPushButton("Toggle italic");
          connect(italicButton, &QPushButton::clicked, this, &MainWidget::toggleItalic);
          m_buttonLayout->addWidget(italicButton, 9, 0);

          m_legendPosX = new QDoubleSpinBox();
          m_legendPosY = new QDoubleSpinBox();
          m_legendWidth = new QDoubleSpinBox();
          m_legendHeight = new QDoubleSpinBox();

          connect(m_legendPosX,
                  static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
                  this, &MainWidget::updateLegendLayout);
          connect(m_legendPosY,
                  static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
                  this, &MainWidget::updateLegendLayout);
          connect(m_legendWidth,
                  static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
                  this, &MainWidget::updateLegendLayout);
          connect(m_legendHeight,
                  static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
                  this, &MainWidget::updateLegendLayout);

          QFormLayout *legendLayout = new QFormLayout();
          legendLayout->addRow("HPos", m_legendPosX);
          legendLayout->addRow("VPos", m_legendPosY);
          legendLayout->addRow("Width", m_legendWidth);
          legendLayout->addRow("Height", m_legendHeight);
          m_legendSettings = new QGroupBox("Detached legend");
          m_legendSettings->setLayout(legendLayout);
          m_buttonLayout->addWidget(m_legendSettings);
          m_legendSettings->setVisible(false);

          // Create chart view with the chart
          m_chart = new QChart();
          m_chartView = new QChartView(m_chart, this);

          // Create spinbox to modify font size
          m_fontSize = new QDoubleSpinBox();
          m_fontSize->setValue(m_chart->legend()->font().pointSizeF());
          connect(m_fontSize,
                  static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
                  this, &MainWidget::fontSizeChanged);

          QFormLayout *fontLayout = new QFormLayout();
          fontLayout->addRow("Legend font size", m_fontSize);

          // Create layout for grid and detached legend
          m_mainLayout = new QGridLayout();
          m_mainLayout->addLayout(m_buttonLayout, 0, 0);
          m_mainLayout->addLayout(fontLayout, 1, 0);
          m_mainLayout->addWidget(m_chartView, 0, 1, 3, 1);
          setLayout(m_mainLayout);

          createSeries();
      }

      void MainWidget::createSeries()
      {
          m_series = new QBarSeries();
          addBarset();
          addBarset();
          addBarset();
          addBarset();

          m_chart->addSeries(m_series);
          m_chart->setTitle("Legend detach example");
          m_chart->createDefaultAxes();
          m_chart->legend()->setVisible(true);
          m_chart->legend()->setAlignment(Qt::AlignBottom);

          m_chartView->setRenderHint(QPainter::Antialiasing);
      }

      void MainWidget::showLegendSpinbox()
      {
          m_legendSettings->setVisible(true);
          QRectF chartViewRect = m_chartView->rect();

          m_legendPosX->setMinimum(0);
          m_legendPosX->setMaximum(chartViewRect.width());
          m_legendPosX->setValue(150);

          m_legendPosY->setMinimum(0);
          m_legendPosY->setMaximum(chartViewRect.height());
          m_legendPosY->setValue(150);

          m_legendWidth->setMinimum(0);
          m_legendWidth->setMaximum(chartViewRect.width());
          m_legendWidth->setValue(150);

          m_legendHeight->setMinimum(0);
          m_legendHeight->setMaximum(chartViewRect.height());
          m_legendHeight->setValue(75);
      }

      void MainWidget::hideLegendSpinbox()
      {
          m_legendSettings->setVisible(false);
      }

      void MainWidget::toggleAttached()
      {
          QLegend *legend = m_chart->legend();
          if (legend->isAttachedToChart()) {
              legend->detachFromChart();
              m_chart->legend()->setBackgroundVisible(true);
              m_chart->legend()->setBrush(QBrush(QColor(128, 128, 128, 128)));
              m_chart->legend()->setPen(QPen(QColor(192, 192, 192, 192)));
              showLegendSpinbox();
              updateLegendLayout();
          } else {
              legend->attachToChart();
              legend->setBackgroundVisible(false);
              hideLegendSpinbox();
          }
          update();
      }

      void MainWidget::addBarset()
      {
          QBarSet *barSet = new QBarSet(QString("set ") + QString::number(m_series->count()));
          qreal delta = m_series->count() * 0.1;
          *barSet << 1 + delta << 2 + delta << 3 + delta << 4 + delta;
          m_series->append(barSet);
      }

      void MainWidget::removeBarset()
      {
          QList<QBarSet *> sets = m_series->barSets();
          if (sets.count() > 0) {
              m_series->remove(sets.at(sets.count() - 1));
          }
      }

      void MainWidget::setLegendAlignment()
      {
          QPushButton *button = qobject_cast<QPushButton *>(sender());

          switch (m_chart->legend()->alignment()) {
          case Qt::AlignTop:
              m_chart->legend()->setAlignment(Qt::AlignLeft);
              if (button)
                  button->setText("Align (Left)");
              break;
          case Qt::AlignLeft:
              m_chart->legend()->setAlignment(Qt::AlignBottom);
              if (button)
                  button->setText("Align (Bottom)");
              break;
          case Qt::AlignBottom:
              m_chart->legend()->setAlignment(Qt::AlignRight);
              if (button)
                  button->setText("Align (Right)");
              break;
          default:
              if (button)
                  button->setText("Align (Top)");
              m_chart->legend()->setAlignment(Qt::AlignTop);
              break;
          }
      }

      void MainWidget::toggleBold()
      {
          QFont font = m_chart->legend()->font();
          font.setBold(!font.bold());
          m_chart->legend()->setFont(font);
      }

      void MainWidget::toggleItalic()
      {
          QFont font = m_chart->legend()->font();
          font.setItalic(!font.italic());
          m_chart->legend()->setFont(font);
      }

      void MainWidget::fontSizeChanged()
      {
          QFont font = m_chart->legend()->font();
          font.setPointSizeF(m_fontSize->value());
          m_chart->legend()->setFont(font);
      }

      void MainWidget::updateLegendLayout()
      {
          m_chart->legend()->setGeometry(QRectF(m_legendPosX->value(),
                                                m_legendPosY->value(),
                                                m_legendWidth->value(),
                                                m_legendHeight->value()));
          m_chart->legend()->update();
      }