[Qt-interest] Using QAbstractTableModel with Custom Class

[Bill Moo]

On Wed, Jun 30, 2010 at 1:13 PM, Andre Somers <andre at familiesomers.nl>wrote:

> On 30-6-2010 12:43, Bill Moo wrote:
> > Hello List,
> >
> > I have a class that does some work, and this work runs on internal
> > threads. In order to keep the user informed of the progress of each
> > instance I thought that by using a Model based QTableView I could
> > eliminate some of the hard work.
> >
> > What I want to do a to create a QMap < int, Worker * > where the int
> > is the row number in view and the Worker * is an instance my class
> > that does all the hard work. However, what I can't get my head round
> > (assuming it is even possible) is how do I display the Worker's
> > internal member variable values in the grid? (as some of these are
> > updated by the internal processes).
> >
> > So assuming for example my QMap contained wto entries what I'd want to
> > see in the QTableView are two rows by x rows (with headers). Column 0
> > would display the name of the file currently being processed, the next
> > column would display the number of lines to process in this file, the
> > third column would display the number of rows processed so far.
> >
> > Is this even possible, or is it the Worker that needs to be a
> > derivative of QAbstractTable | Item Model I have googled of course but
> > I've not found anythign that comes close.
> Totally possible, and doable.
>
> As you are not dealing with a hierarchical model, I'd go for
> QAbstractTableModel as the base class. As Mandeep mentioned, you start
> with reimplementing the basic methods of that class: rowCount(),
> columnCount() and data(). As the documentation mentions, you should
> probably also reimplement headerData(). That would allow you to set the
> headers for the table you want to make.
>
> Your implementation should have access to the class that
> contains/manages the threads that do the work.
>
> Your rows() reimplementation would returns the number of treads that you
> have working, that is QMap::count() in your case.
> Your columns() would return the number of properties you want to show
> for each of them, 3 in your case.
> Your data() would access the information you need from the Workers. I
> think you can get away with just reading the values, even if they are
> not protected by a mutex, but you should test that I guess.
>
> Your workers do not need to be adjusted at all. The model you are
> creating is just an interface you implement that you can use to query
> data from your internal system for display later on. So, it needs to be
> able to access that data, but it does not need any inheritance
> otherwise, nor do the classes that actually provide the data need to
> know about it if the information you want to display is available in
> their public interface. So, to answer your question "how do I display
> the Worker's internal member variable values in the grid", I would
> suggest you add at least read access to those values in the public
> interface of your workers. Just provide a int lineCount() const;
> function, for instance.
>
> Then, you probably also want to make the display update when the workers
> make progress, right? So, fit your workers to emit signals when
> something happens that the outside world may care about, such as changes
> in what file is being worked on or the current line number. Your model
> can connect to those signals. I would use a QSignalMapper inside the
> model to map the worker back to a row number. Then, you can have your
> model emit the dataChanged() signal to notify the views that the data
> has changed.
>
> André
>
> P.S.
> For spicing things up a little but, you could look into displaying a
> progress bar in the last column. Qxt provides a delegate that can do that.
>
>
Excellent, turned out I was on the right track after all, thank you all for
your input. But I may be back with other questions later. Thank you all.

-- 
Bill
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