[Qt-interest] How to change QState when clicking a QListView

[François KUBLER]

Hi list,

I'd like to thank K. Frank for his help. The QStateMachine::QSignalEvent.arguments() was exactly what I was missing. The problem isn't fully solved but it's now between me and Python!

Well, thanks again, I hope I can help you back someday.

-- 
François

"K. Frank" <kfrank29.c at gmail.com> a écrit :

>Hello François -
>
>See response, below.
>
>2010/8/6 Mandeep Sandhu <mandeepsandhu.chd at gmail.com>:
>> Since you are only passing the QModelindex around, I assume you'll
>> have access to the model in your 'playerState'.
>> ...
>>> But I'd need both (retrieve the clicked item + go to the targeted state).
>>> ...
>>> François
>
>> Thanks a lot your answer !
>> Just to be sure I've understand, I should basically :
>
>I'm not that familiar with the specifics of Qt's state-machine framework,
>but I can give you my thoughts on how it might work.
>
>> - Build a custom QEvent, let's say "ItemClickEvent", with a "data"
>> property,
>
>Yes, and the "data" property would tell you which item in your
>list had been clicked.
>
>> - Set my QListView to accept "ItemClickedEvent",
>
>This I don't follow.  I don't see why you would be sending this
>(or any other event) to your QListView.
>
>> - Connect the QAbstractView::clicked ( const QModelIndex &index ) signal
>> to a custom slot (which I already do),
>
>Yes, you would have some slot which translates the signal to
>an event.  (But you may be able to avoid this step: see below.)
>The slot then instantiates an ItemClickedEvent, sets its "data"
>property to index (the signal's argument), and posts the event
>to your state machine.
>
>> - Add a transition from my source state to my targeted state when the
>> ItemClickedEvent occurs (using a QEventTransition),
>
>Yes, your "listState" would have a transition triggered by the
>IntemClickedEvent that takes it to your "playerState."
>
>> - In my custom slot, instantiate my ItemClickedEvent class, set its "data"
>> property to whatever I need,
>
>Yes, and presumably what you need is to set "data" to index, the
>argument of the clicked signal.
>
>> and send the Event via
>> QCoreApplication::notify(),
>
>I could be wrong, but since your dealing with a state machine, it's
>probably more appropriate to use QStateMachine.postEvent().
>In somewhat compressed form:
>
>   stateMachine.postEvent (new ItemClickedEvent (index));
>
>(For all I know, postEvent and notify may be equivalent, in that
>postEvent may resolve to notify under the hood.)
>
>> - And finally, use the event handed to my target state onEntry() method.
>
>Yes (presumably your target state is your 'playerState'), and in
>particular, query the event for the index of the item clicked.
>
>> (I tried something quite similar, but, instead of sending a QEvent, I
>> tried to send a custom signal -and it didn't work-.)
>
>Following up on my earlier comment, it looks like Qt's state-machine
>framework does support using signals instead of events (which it
>then wraps as events for you).
>
>If I understand this correctly, you could forgo defining a custom
>event (the ItemClickedEvent), and having your slot instantiate and
>post this event.
>
>QState has a version of addTransition that takes signals:
>
>   QSignalTransition *addTransition (QObject *sender, const char
>*signal, QAbstractState *target)
>
>So, as I understand it, you could do something like this:
>
>   listState->addTransition (listView, SIGNAL (clicked (const
>QModelIndex &index)), playerState);
>
>Then when the signal fires, your state machine gets a
>QStateMachine::SignalEvent that ultimately gets passed
>to playerState->onEntry(), and the index argument of the
>clicked signal appears to be exposed through
>QStateMachine::SignalEvent.arguments().
>
>So it looks like in terms of mapping the signal to an event,
>instantiating the event, and then posting it, Qt will do all
>that work for you, so you can save a few lines of typing,
>and not have to write your own custom slot and event.
>
>> Thanks again for your help, I really appreciate it !
>>
>> François
>
>Good luck.
>
>
>K. Frank
>
>_______________________________________________
>Qt-interest mailing list
>Qt-interest at trolltech.com
>http://lists.trolltech.com/mailman/listinfo/qt-interest