mainwidget.cpp Example File

legend/mainwidget.cpp
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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();
 }