ubuntu-phone team mailing list archive

[Michael Zanetti <michael.zanetti@xxxxxxxxxxxxx>]

On Monday 30 September 2013 12:05:03 Николай Шатохин wrote:
> Can I set only one object as context property that contains other objects
> (and this objects contain objects too) and get this deep objects in QML?
> 
> For i.e. I have object of class Engine that has object of class Game, Game
> contains object of Ship and Ship contains object of Reactor. So, I set
> object of Engine as context property and in QML write:
> 
> engine.game.ship.reactor
> 
> Can I use it?


Yes, given that "game" is a Q_PROPERTY() of "enigne", "ship" is a Q_PROPERTY() 
of "game" etc...

Still, I recommend to register the type of the Engine instead of setting it as 
a context property.

It's really just using qmlRegisterType() instead of setContextProperty(). It's 
not more or more complex code, but gives you better ways of structuring your 
QML code.

> 
> 
> 2013/9/30 Николай Шатохин <n.shatokhin@xxxxxxxxx>
> 
> > I've already found this solution:
> > http://qt-project.org/doc/qt-5.0/qtqml/qtqml-cppintegration-contextpropert
> > ies.html It helps. Thanks.
> > 
> > 
> > 2013/9/30 Michael Zanetti <michael.zanetti@xxxxxxxxxxxxx>
> > 
> >> On Sunday 29 September 2013 13:45:01 Vladimir M. wrote:
> >> > Sounds like a "context property" use case (you plain set a QObject as a
> >> > context property for a view's root scope, w/o even registering the
> >> 
> >> object's
> >> 
> >> > type, and all its properties and invokables become available).
> >> 
> >> I don't recommend using context properties. While they are useful for
> >> some
> >> cases, this one doesn't seem to be one of those. Using too many global
> >> context
> >> properties can make the code very ugly to work with.
> >> 
> >> You probably want to create something like this:
> >> 
> >> class ViewController: public QObject
> >> {
> >> 
> >>   Q_PROPERTY(QList<MyClass> viewObjects READ viewObjects NOTIFY
> >> 
> >> viewObjectsChanged)
> >> ...
> >> QList<MyClass> viewObjects() const {
> >> 
> >>   return objectList;
> >> 
> >> }
> >> ...
> >> };
> >> 
> >> qmlRegisterType<ViewController>(uri, 0, 1, "ViewController");
> >> 
> >> Then in QML you can do something like this:
> >> 
> >> ViewController {
> >> 
> >>   id: viewController
> >> 
> >> }
> >> 
> >> Repeater {
> >> 
> >>   model: viewController.viewObjects
> >>   MyView {
> >>   
> >>     property var viewObject: viewController.viewObjects[index]
> >>   
> >>   }
> >> 
> >> }
> >> 
> >> 
> >> Note that if you want your code to adjust more flexible (i.e. the
> >> viewObjects
> >> change a lot), consider using a QAbstractListModel (or some other model)
> >> instead of a QList.
> >> 
> >> Hope this helps,
> >> Michael
> >> 
> >> > On Sun, Sep 29, 2013 at 6:38 AM, Николай Шатохин
> >> 
> >> <n.shatokhin@xxxxxxxxx>wrote:
> >> > > Hello.
> >> > > 
> >> > > When I create a class in C++, I can register it for QML and can
> >> > > create
> >> > > view for it. It's very convenient. But, if I need many objects of the
> >> 
> >> same
> >> 
> >> > > type, and need to show few views on screen, I got problems.
> >> > > Is it possible to register QML type for object, not for class?
> >> > > If I change some object, I need to see only its view changed.
> >> > > 
> >> > > Best regard,
> >> > > Nick
> >> > > 
> >> > > --
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