QCheckBox as QTableView delegate

Delegate, qcheckbox, qcheckbox center, QTableView

Good day.
There was a need to use a delegate to display QCheckBox in the table (to select objects from the list for subsequent work with them).
In order to deal with the delegates, I created a small project.
At the output we get the following:

Project structure:

checkboxdelegate.h

#ifndef CHECKBOXDELEGATE_H
#define CHECKBOXDELEGATE_H
#include <QStyledItemDelegate>
 
 
class CheckBoxDelegate : public QStyledItemDelegate
{
    Q_OBJECT
 
public:
    CheckBoxDelegate(QObject *parent = nullptr);
 
    // QAbstractItemDelegate interface
public:
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;
    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const;
    void setEditorData(QWidget *editor, const QModelIndex &index) const;
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const;
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const;
};
 
#endif // CHECKBOXDELEGATE_H
 

checkboxdelegate.cpp

#include "checkboxdelegate.h"
#include <QCheckBox>
#include <QApplication>
 
CheckBoxDelegate::CheckBoxDelegate(QObject *parent)
    :QStyledItemDelegate (parent)
{
 
}
 
QWidget *CheckBoxDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    Q_UNUSED(option)
    Q_UNUSED(index)
 
    //Cоздаем checkbox editor
    QCheckBox *editor = new QCheckBox(parent);
    return editor;
}
 
void CheckBoxDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    //Установливаем выбрано/не выбрано
    QCheckBox *cb = qobject_cast<QCheckBox *>(editor);
    cb->setChecked(index.data().toBool());
}
 
void CheckBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    //Записываем данные в модель
    QCheckBox *cb = static_cast<QCheckBox *>(editor);
    int value = (cb->checkState()==Qt::Checked)? 1 : 0;
    model->setData(index, value, Qt::EditRole);
}
 
void CheckBoxDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    Q_UNUSED(index);
    QStyleOptionButton checkboxstyle;
    QRect checkbox_rect = QApplication::style()->subElementRect(QStyle::SE_CheckBoxIndicator, &checkboxstyle);
 
    //Центрирование
    checkboxstyle.rect = option.rect;
    checkboxstyle.rect.setLeft(option.rect.x() +
                               option.rect.width()/2 - checkbox_rect.width()/2);
 
    editor->setGeometry(checkboxstyle.rect);
}
 
 
void CheckBoxDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    //Получаем данные
    bool data = index.model()->data(index, Qt::DisplayRole).toBool();
 
    //Создаем стиль CheckBox
    QStyleOptionButton checkboxstyle;
    QRect checkbox_rect = QApplication::style()->subElementRect(QStyle::SE_CheckBoxIndicator, &checkboxstyle);
 
    //Центрирование
    checkboxstyle.rect = option.rect;
    checkboxstyle.rect.setLeft(option.rect.x() +
                               option.rect.width()/2 - checkbox_rect.width()/2);
    //Выбрано или не выбрано
    if(data)
        checkboxstyle.state = QStyle::State_On|QStyle::State_Enabled;
    else
        checkboxstyle.state = QStyle::State_Off|QStyle::State_Enabled;
 
    //Готово! Отображаем!
    QApplication::style()->drawControl(QStyle::CE_CheckBox, &checkboxstyle, painter);
}
 

main.cpp

#include "checkboxdelegate.h"
#include <QApplication>
#include <QStandardItemModel>
#include <QHeaderView>
#include <QTableView>
 
#define MODEL_ROWS 4            //Количество строк модели
#define MODEL_COLUMN 2          //Количество столбцов модели
#define DELEGATE_COLUMN 0       //Столбец с делегатом
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    //Создаем модель и представление
    QStandardItemModel *model = new QStandardItemModel(MODEL_ROWS, MODEL_COLUMN);
    QTableView *tableView = new QTableView();
    CheckBoxDelegate *delegate = new CheckBoxDelegate();
 
    //Заолняем модель данными
    for (int row =0; row < MODEL_ROWS; ++row) {
        for (int column = 0; column < MODEL_COLUMN; ++column) {
            QModelIndex index = model->index(row, column, QModelIndex());
            if(column == 0)
                model->setData(index, QVariant(0));
            else
                model->setData(index, QVariant((row + 1) * (column + 1)));
        }
 
    }
    //Устанавливаем модель в представление
    tableView->setModel(model);
    //Устанавливаем делегат в столбец
    tableView->setItemDelegateForColumn(DELEGATE_COLUMN, delegate);
    //Внешний вид предтавления
    tableView->resizeColumnsToContents();
    tableView->verticalHeader()->hide();
    tableView->horizontalHeader()->setStretchLastSection(true);
 
    tableView->setWindowTitle("Check Box Delegate");
    tableView->show();
 
    return a.exec();
}
 

Project file:

CheckBoxDelegate_PG92889.7z

The only problem is that you have to double-click the QCheckBox to select it. It turns out that the cell is allocated at first. and only then the focus already falls on the widget.