QTableView and display of doubles

[ChrisW67]

If you want custom painting then you have to do the work to honour selections and the like and adjust the colours accordingly. You use the data in the QStyleOptionViewItem to achieve that, e.g:

// something like this
painter->save();
if (option.state & QStyle::State_Selected) {
  painter->fillRect(option.rect, option.palette.highlight());
  painter->setPen(...); // use option.palette.highlightedText()
  painter->drawText(...);
}
else {
  painter->fillRect(option.rect, option.palette.base());
  painter->setPen(...); // use option.palette.text()
  painter->drawText(...);
}
painter->restore();

// something like this
painter->save();
if (option.state & QStyle::State_Selected) {
  painter->fillRect(option.rect, option.palette.highlight());
  painter->setPen(...); // use option.palette.highlightedText()
  painter->drawText(...);
}
else {
  painter->fillRect(option.rect, option.palette.base());
  painter->setPen(...); // use option.palette.text()
  painter->drawText(...);
}
painter->restore();

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That's why I suggested just overriding QStyledItemDelegate::displayText() to change just the text that the default delegate painting then renders.

[b1]

Thanks ChrisW67,

I thought I would try the overriding idea and I have failed to get it to work.

QString SpinBoxDelegate::displayText(const QVariant &value, const QLocale &locale) const
{
	if (value.userType() == QVariant::Double )
	{
		return locale.toString(value.toDouble(), 'f', 1);
	}
	else
	{
		return QStyledItemDelegate::displayText( value, locale);
 
	}
};

QString SpinBoxDelegate::displayText(const QVariant &value, const QLocale &locale) const
{
	if (value.userType() == QVariant::Double )
	{
		return locale.toString(value.toDouble(), 'f', 1);
	}
	else
	{
		return QStyledItemDelegate::displayText( value, locale);
		
	}
};

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This doesn't compile with this error message:

error: cannot call member function 'virtual QString QStyledItemDelegate::displayText(const QVariant&, const QLocale&) const' without object

I didn't think an object was needed in this case...
All the examples I have found seem to do it this way so any suggestions on where I have gone wrong would be appreciated?

Thanks, B1.

[d_stranz]

Is your SpinBoxDelegate class derived from QStyledItemDelegate? If it is not, then you can't call a member function for a class that is unrelated to yours. That's what the compiler is trying to tell you: since your class is not derived from QStyledItemDelegate, "this" is not a QStyledItemDelegate, so in order to call one of the QStyledItemDelegate methods, you need an instance of that kind of object.

The solution is simple:

class SpinBoxDelegate : public QStyledItemDelegate
{
  // ...
};

class SpinBoxDelegate : public QStyledItemDelegate
{
  // ...
};

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Then your displayText() method will compile and work as you expect.

[b1]

Thank you d_stranz,

You are correct, it was simple and it worked. I couldn't see the wood for the trees!!!

Thank you to all who answered,

B1.