Qt: CheckBoxDelegate class

checkboxdelegate.cpp

#include "checkboxdelegate.h"

#include <QApplication>

CheckBoxDelegate::CheckBoxDelegate(QObject *parent) : QStyledItemDelegate(parent), scale(1.1) {}

void CheckBoxDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QRect rect(option.rect.left() / scale, option.rect.top() / scale, option.rect.width() / scale, option.rect.height() / scale);
    painter->save();
    painter->scale(scale, scale);

    if (option.state & QStyle::State_Selected)
        painter->fillRect(rect, option.palette.highlight());

    QStyleOptionButton cbIndicator;
    cbIndicator.rect = rect;
    cbIndicator.state = QStyle::State_Enabled | (index.data().toBool() ? QStyle::State_On : QStyle::State_Off);
    QApplication::style()->drawControl(QStyle::CE_CheckBox, &cbIndicator, painter);
    painter->restore();
}

bool CheckBoxDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
    if (event->type() == QEvent::MouseButtonRelease)
    {
        model->setData(index, !index.data().toBool());  // toggle checkbox state
        return true;
    }

    return QStyledItemDelegate::editorEvent(event, model, option, index);
}

qreal CheckBoxDelegate::getScale() const
{
    return scale;
}

void CheckBoxDelegate::setScale(const qreal &value)
{
    scale = value;
}

checkboxdelegate.h

#ifndef CHECKBOXDELEGATE_H
#define CHECKBOXDELEGATE_H

#include <QObject>
#include <QStyledItemDelegate>
#include <QPainter>

class CheckBoxDelegate : public QStyledItemDelegate
{

public:
    CheckBoxDelegate(QObject* parent = nullptr);
    qreal getScale() const;
    void setScale(const qreal &value);

protected:
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) override;

private:
    qreal scale;

};

#endif // CHECKBOXDELEGATE_H

Checkbox for TableWidgets / TableViews
features a scale factor to make the checkboxes a bit bigger, if desired