checkbox and itemdelegate in a tableview

If you are extending the QItemDelegate class, it has a drawCheck() function, what will draw you a nince, centered checkbox. You can use it in the paint() function.

Edit:

Here is an example, assuming you have a class called BooleanEditor, what inherits from QItemDelegate:

void BooleanEditor::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    drawCheck(painter, option, option.rect, index.data().toBool() ? Qt::Checked : Qt::Unchecked);
    drawFocus(painter, option, option.rect);
}

For keeping the checkbox centered when entering the edit mode, you can do something like this:

class BooleanWidget : public QWidget
{
    Q_OBJECT
    QCheckBox * checkBox;

    public:
    BooleanWidget(QWidget * parent = 0)
    {
        checkBox = new QCheckBox(this);
        QHBoxLayout * layout = new QHBoxLayout(this);
        layout->addWidget(checkBox,0, Qt::AlignCenter);
    }

    bool isChecked(){return checkBox->isChecked();}
    void setChecked(bool value){checkBox->setChecked(value);}
};

And in your ItemDelegates createEditor() method return an instance of this BooleanWidget class. In your setModelData() and setEditorData() you can now cast your input widget to this BooleanWidget:

BooleanWidget * widget = qobject_cast<BooleanWidget*>(editor);

and then use the is/setChecked method.

I solve this problem with the following item delegate:

booleanitemdelegate.h

#ifndef BOOLEANITEMDELEGATE_H
#define BOOLEANITEMDELEGATE_H

#include <QItemDelegate>



class BooleanItemDelegate : public QItemDelegate
{
public:
    BooleanItemDelegate(QObject *parent);

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

#endif // BOOLEANITEMDELEGATE_H

booleanitemdelegate.cpp

#include "booleanitemdelegate.h"

BooleanItemDelegate::BooleanItemDelegate(QObject *parent):
    QItemDelegate(parent)
{

}

void BooleanItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    drawCheck(painter, option, option.rect, index.data().toBool() ? Qt::Checked : Qt::Unchecked);
    drawFocus(painter, option, option.rect);
}

bool BooleanItemDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
    if(event->type() == QEvent::MouseButtonRelease){
        model->setData(index, !model->data(index).toBool());
        event->accept();
    }
    return QItemDelegate::editorEvent(event, model, option, index);
}

I hope, I can help.

that's what I did to center-allign the editor control:

QWidget *checkBoxDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const {
    QCheckBox *editor = new QCheckBox(parent);
    editor->setTristate(allowTriState); //my class' variable
    // this does the trick :)
    editor->setStyleSheet("QCheckBox {margin-left: 43%; margin-right: 57%;}"); 
    // this should do it better
    // editor->setStyleSheet("QCheckBox {margin-left: auto; margin-right: auto;}");
    // but in my case the checkbox is slightly to the left of original
    return editor;
}