[Interest] How to create a custom Model

Knut Krause knut.krause at lagom.de
Fri Nov 16 16:56:17 CET 2012


As a beginners project (I'm quite new to both C++ and Qt) I thought about 
developing a little GPS application since there'd be a lot to play around 
(XML, Model/View, QWT, OpenGL and son on ;-) )

Now my first question: How would you implement the underlying model? Since main 
gpx structure (the interests me in the beginning) is


as seen at [1] my model is going to be a tree. So AFAIK two approaches would 
be valid: QAbstractItemModel and QStandardItemModel.

The first approach would be somehow like [2] I think but since it's so simple 
it lacks write functionality I'm not sure yet how I'd implement that in 
semantically correct way. I found other people pointing out the advantages of 
QStandardItemModel at [3].

Now if I create the model I'd like to keep the semantic in the gpx data. It'd 
be great if I could call functions like "QDateTime TrackPoint::time()" and so 
on later so the Views can use the QModelIndex approach and I myself can access 
the model in a more intuitive way in my code when I want to smooth the whole 
track for example or find the highest point and so on.

How would you implement such a model?



[1] https://en.wikipedia.org/wiki/GPS_eXchange_Format#Sample_GPX_document
[2] http://doc.qt.digia.com/4.8-snapshot/itemviews-simpletreemodel.html
[3] https://invalidmagic.wordpress.com/2010/09/20/qabstractitemmodel-vs-

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