[Qt-interest] Tree Item view Highlighter

[Sajjad]

On Tue, Jan 4, 2011 at 10:21 AM, Andre Somers <andre at familiesomers.nl>wrote:

> Op Di, 4 januari, 2011 9:21 am, schreef Sajjad:
>
> >>  Is there anything missing up there? I removed the other function that i
> >> over-rid mentioned in the previous post.
> >>
> >>  I am still not getting any effect. The textchanged() signal is
> >> connected
> >> to  the slot as before.
> >>
> >> Ah, of course... Sorry about that.
> >>
> >> First of all: are you getting an effect if you set a fixed regexp to
> >> begin
> >> with? If not, then something is wrong in the code above. Set a
> >> breakpoint
> >> where you return the color and see if you ever arrive there at all...
> >>
> >
> > I set the breakpoint at the slot
> >
> >   void H3DNodeListWidget::highlightRegExpChanged()
> >
> > {
> >
> >     QRegExp
> >
> regExp(m_nodeHighlightingEditor->text(),Qt::CaseInsensitive,QRegExp::FixedString);
> >
> >      m_highlightModel->setFilterRegExp(regExp);
> >
> > }
> >
> I meant setting the breakpoint in the data() function.
>

The breakpoint  has been set there as well.

>
> > And i did not reach  the data() function while stepping into the code.
> I can imagine it did not.
>
> >> However, I think the problem is, that you need to notify your view that
> >> the
> >> data has changed if your regexp changes. For testing, just emit reset(),
> >> but
> >> in your real implementation, you should probably be a bit nicer and emit
> >> dataChanged() with the right modelindexes.
> >>
>
i believ ethat the dataChanged() signal two model indexes as input
parameter. I need to highlight only one tree item that maches the expression
in the line edit. In that case how should i set the value for the signal
that takes 2 input parameters. Should it be the same source index specified
twice? I tried something as follows:

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

  QVariant H3DHighlighterProxyModel::data(const QModelIndex &index,
int role) const

{

    //get  the handle to  the underlyiing data

    QModelIndex  sourceIndex = mapToSource(index);

     if(!sourceIndex.isValid())

    {

        return QVariant();

    }

     if(role == Qt::BackgroundRole)

    {

        if(sourceModel()->data(sourceIndex).toString().contains(filterRegExp()))

        {

            //the following statement gives error because the virtual
function itself

            //declared const

            emit dataChanged(sourceIndex,sourceIndex);

            return Qt::cyan;

        }

        else

        {

            //return the default background color

            //whatever may it be

            return QVariant();

        }

    }

    else

    {

        return sourceIndex.data(role);

    }

}


////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////


And then if i have to set the connection as follows, i believe that it will
not be valid:

connect(m_proxyMode,dataChanged(QModelIndex,QModelIndex),m_treeView,SLOT(update(QModelIndex))));

As you can see that the parameters are not matching.

>From all  the discussions you can imagine that i am having trouble to grasp
the basic idea of model.view programming.
Could you provide some references where these issues are well discussed?


Regards
Sajjad



> >
> > I did not understand that part. A bit more elaboration might be helpful.
>
> Ok, let me try. If you set a new regexp, you expect part of the data to
> change (the background color for some of the items in your model). But how
> is the view to know that? It needs to be told that the data has changed,
> so it can redraw itself. Of course, Qt uses signals and slots for that.
> The elegant way to do it is to tell the view exactly which items have
> changed by emitting the (proxy-) models changedData signal with the range
> of items that have changed. The more course that range is, the more
> repainting and requerying of the model the view may have to do. The most
> course way is to reset the model completely. This will cause a complete
> reset of the view, including the current selection, the current view
> position, etc.
>
> You need to signal that change from the slot where you set the new regexp.
> That should trigger the view to start requerying the model for the updated
> data, and redraw the view appropriately.
>
> André
>
>
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