[Qt-qml] Possibility of an implementation approach?

[ray.rischpater at nokia.com]

My first medium-sized-ish QML application was one very similar to what you're proposing, and the approach worked very well. Two comments...
You'll want to use a C++ model to back your UI for your network resources; that way you can update the model from C++ and the UI will automatically redraw. You'll want to create a subclass of QAbstractListModel, or use a subclass like QStandardItemModel (which is fine for general lightweight work), and jam that puppy into your QML context (http://doc.qt.nokia.com/4.7-snapshot/qtbinding.html#embedding-c-objects-into-qml-components, http://www.lothlorien.com/kf6gpe/?p=160). Using a model is preferable to using QList<T>, because as the model changes, it signals to the UI to change automatically. In my case, I created a QStandardItemModel subclass that was a back-end listening to QtDBus notifications, so signals on the DBus propagated to, and seamlessly updated, my QML interface. It worked very well.

You can wire stuff back to your C++ app from your QML's ListView delegate by using a MouseArea that dispatches to a Q_INVOKABLE property on an object shared between C++ and QML; see the previous links as  well. I found it pretty handy (if a bit sloppy) to make my application controller class available in QML, and then just put some Q_INVOKABLE methods on it so that the QML could trigger state changes in the app controller logic. So your app controller could have a Q_INVOKABLE method "doSomething" that the MouseArea onClicked handler invokes, passing whatever info from the current item of the model is necessary to your application logic.

Hope that helps!

Cheers,
R.


-----Original Message-----
From: qt-qml-bounces+ray.rischpater=nokia.com at qt.nokia.com [mailto:qt-qml-bounces+ray.rischpater=nokia.com at qt.nokia.com] On Behalf Of ext Christian Benjamin Ries
Sent: Wednesday, September 07, 2011 6:17 AM
To: qt-qml at qt.nokia.com
Subject: [Qt-qml] Possibility of an implementation approach?

Hello all together!

I rechecherd a little bit and checked out the possibilities of QML, everything sounds nice and easy to apply. I already checked how I can add an QML declarative object to a GraphicScene and how I could move them around.

Now I stuck, I've no idea if I can use QML efficiently in my project.

Here a small description of my task:

- I have to create a graphical view of some elements, e.g. a host with included childs like network-interface cards.

- These hosts could have descriptions for file-shares, and I like to add them to the host on the fly by a C++-programm, and the view sould be repaint in the QGraphicalView.

- I have seen, that I can add a list<T> in QML, could I add elements to this list by C++? If yes, could you give me an example or a link to one example?

- Furthermore, when I click a one MouseArea I like to use this click-Signal in my C++-programm, but there is no available example on the Qt's-website, right?

I really like to use QML, because it could safe a lot of time! Because their is no need to create items of all elements with a QGraphicsItem based spezialization, and the calculation of all positions and so on...

I really checked the web and Qt's documentation, but the available examples covers not really an example how I could do the mentioned implementation things.

Suggestions will be welcome(!)

All the best, Christian
_______________________________________________
Qt-qml mailing list
Qt-qml at qt.nokia.com
http://lists.qt.nokia.com/mailman/listinfo/qt-qml