Need help with my delegate

[Guilo]

Hi !

I am using a custom delegate to display my qlistview. Indeed, I want each of the items to be written on two lines and using html syntax to highlight it. No need for editing the items so I have just reimplemented the painter method :

void AlertDelegate::paint (QPainter *painter, const QStyleOptionViewItem& option, const QModelIndex& index ) const {
 
    painter->save();
       QTextDocument doc;
       doc.setHtml( index.data().toString() );
       QAbstractTextDocumentLayout::PaintContext context;
       doc.setPageSize(option.rect.size());
       painter->translate(option.rect.x(), option.rect.y());
       doc.documentLayout()->draw(painter, context);
       painter->restore();
}

void AlertDelegate::paint (QPainter *painter, const QStyleOptionViewItem& option, const QModelIndex& index ) const {

    painter->save();
       QTextDocument doc;
       doc.setHtml( index.data().toString() );
       QAbstractTextDocumentLayout::PaintContext context;
       doc.setPageSize(option.rect.size());
       painter->translate(option.rect.x(), option.rect.y());
       doc.documentLayout()->draw(painter, context);
       painter->restore();
}

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But the problem is that the first line of the second item is written on the second line of the first item. Where is the problem ?


Thanks

[tbscope]

You should also implement sizeHint() to let the view know how big each item is.
I guess in your case, you could just double the height (more or less).

[Guilo]

Is sizeHint a method of QItemDelegate or an attribute of QItemDelegate ? Or an attribute of my QTextDocument ? Any example somewhere to implement this ? cause I don't know how to double the actual value.

Thanks

[tbscope]

sizeHint() is a function of a widget which returns how big the widget is.

Example:

QSize AlertDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     // Do some checks with the text document so you know the returned value is correct. If you use a pointer for example, check if it exists. etc...
 
    return myDoubleLineTextDocument.sizeHint();
 }

QSize AlertDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     // Do some checks with the text document so you know the returned value is correct. If you use a pointer for example, check if it exists. etc...

    return myDoubleLineTextDocument.sizeHint();
 }

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You will need to define your textdocument more accessible in your delegate.

[Guilo]

QTextDocument has no member sizeHint()cause it inherits QObject and not QWidget. And what about painter and context ?

[tbscope]

It has a size() function.

Or whatever else that you can use to get the size of the text.

[Guilo]

It works quite great. But each time I update my model (with clear() and appendRow()), some space must appear on the right side of the text beacause the horizontal scrollbar gets smaller each update.