In reimplemented paint function of QItemDelegate, setFont is not working

Question

I have reimplemented paint() function for QTreeWidget, I want to show data of second column bold, but it doesn't work.

How can i fix it?

void extendedQItemDelegate::paint(QPainter *painter,
                                  const QStyleOptionViewItem &option,
                                  const QModelIndex &index) const
{
    const QString txt = index.data().toString();
    painter->save();
    QFont painterFont;
    if (index.column() == 1) {
        painterFont.setBold(true);
        painterFont.setStretch(20);
    }
    painter->setFont(painterFont);
    drawDisplay(painter, option, rect, txt);
    painter->restore();
}

I attached a screen shot of the problem, second half should be bold

screen shot

Please always explain in general how it does not work. It is perhaps even better to provide screenshots if it is a visual issue. — László Papp, Mar 15 '14 at 09:00

score 0 · Answer 1 · answered Mar 15 '14 at 11:38

0

You forgot to add your extendedQItemDelegate to the QTreeView/QTreeWidget object via the setItemDelegate member function.

As an example:

QTreeWidget* tree_view = ...;
extendedQItemDelegate* extended_item_delegate = ...;
tree_view->setItemDelegate(extended_item_delegate);

answered Mar 15 '14 at 11:38

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here is my code :extendedQItemDelegate *delg = new extendedQItemDelegate; treeEvents->setItemDelegate(delg); – mari Mar 15 '14 at 11:46
i googled my probelm and i found that i should change const QStyleOptionViewItem &option font but because it is const i can't change it, i try to change a copy of it but it shows nothing – mari Mar 15 '14 at 11:49

score 0 · Answer 2 · answered Dec 19 '17 at 02:10

You need to make a copy of the const QStyleOptionViewItem &option, apply your font changes to that copy, then paint using your copy instead of the original option passed to the function.

void extendedQItemDelegate::paint(QPainter *painter,
                                  const QStyleOptionViewItem &option,
                                  const QModelIndex &index) const
{
    const QString txt = index.data().toString();
    painter->save();
    QStyleOptionViewItem optCopy = option;     // make a copy to modify
    if (index.column() == 1) {
        optCopy.font.setBold(true);            // set attributes on the copy
        optCopy.font.setStretch(20);
    }
    drawDisplay(painter, optCopy, rect, txt);  // use copy to paint with
    painter->restore();
}

(Just realized this is an old question but it had popped up to the top of qt tags.)

In reimplemented paint function of QItemDelegate, setFont is not working

2 Answers2