In reimplemented paint function of QItemDelegate, setFont is not working - c++

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

Answer 1

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);

Answer 2

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.)