[maemo-developers] New apps for fremantle with Qt?

[From: Karoliina.T.Salminen at nokia.com]

>> On Sat, Sep 5, 2009 at 08:01
>> > However, if you want to have the exact same user experience as the
>> > preinstalled Maemo 5 applications have (as seen in all youtube videos and
>> > the SDK), then you have much easier time and faster development with the
>> > gtk-based hildon widgets in Maemo 5.
>>
>> This doesn't give much of a transition plan for developers, or the
>> chance to fix things in the Qt API whilst it's in "community support"
>> mode.
>
>Before people start jumping into long term conclusions, I'd rather encourage people to start documenting to wiki.maemo.org, what is known about QT in Maemo 5 and build a better understanding collectively there.
>
>I don't know about QT any more than what is publicly informed. Which is very little.
>
>Lets move from the guesswork here to documenting what is really known to wiki.

>
>Big thanks to Kate for the clarifying post. I'm sorry I misunderstood the purpose of QT mobility. Seems it's not about widgets, but about platform components like Contacts and Services.
>
>I would caution against too easily dismissing Hildon Pickers as trivial "composites" that app developers can implement.
>At least in Hildon widgets, Claudio, Berto and others have spent huge amount of time to get the pickers work "just right". You can see it yourself in the hildon git changelog.
>The "combobox" in Linux desktops is pretty much a subset of the hildon pickers (in terms of funtionality, not directly in terms of actual UI elements). So if pickers would be trivial, then why would there be a need to provide a combobox in the standard toolkit?

These things are easier in some toolkits and harder in some others. To my knowledge, Gtk was not really designed for handheld touch user interface
with kinetic scroll etc. on mind in the first place - it is a rather a desktop toolkit with the rather traditional mindset - 
and some of hard core hacking obviously was required to make it function like it functions on the Maemo 5. That is a great achievement and I have
watched that with awe and lots of respect to the developers who have made it. I can now enjoy it every day with my N900, lists etc.
work as they should and they make this UI very desirable.

On the other hand, it was a lot easier to start the same from scratch on Startup wizard with Clutter because there
was not the incompatible way of thinking as a barrier between the desired functionality and what is already there because there was
nothing there already, just start from grass root level from atomic blocks (start by building a custom ClutterActor) 
and then figure out how to stack Actors and how to animated them to get e.g. a kinetic scroll list done. As there was no base widget, there
was no limitations of the base widget and no associated problems, just putting some lego blocks together and it was done. With some
adjustable parameters and then fine tuning the feel with these parameters, it was actually quite efficient to do it. 

I believe Qt can be in the same position pretty much,
if the widget is started from scratch rather basing it on some existing widget which has similar limitations than the equivalent
in the Gtk. Qt is more like Gtk + Clutter combined rather than being equivalent of the Gtk alone. 

Kate said there is some kinetic scroll list already there in the Qt, but I don't know how its parameters match to the 
Hildon/Gtk version we have on the Maemo 5, but I think that with some work it can be done to function 100% equally, as it works
equally on startup wizard despite it is a completely separate implementation with a completely different kind of technology behind it.
And despite of that, it still just works, perfectly. 

IMHO good news about composite widgets is that they are very easy to create in Qt. Many things which are very cryptic in Gtk and glib (no flame intended, I know
that hard core glib people will disagree, but I don't happen to be very enlightened to the gobject despite having made few custom ClutterActors myself in C/glib) are so simple on Qt, 
just few lines of very understandable and easy C++ code. I am sure Kate can show examples. Another good news is that the QGraphicsView appears to have almost everything that is in Clutter, and modern 
mobile user interface widgets can be built with it rather than basing them on the traditional widgets. And what is more, 
Qt allows extensive embedding of the traditional widgets to the graphics view which may make the task even easier.

This sounds so interesting that I may need to look into it someday. 

>I managed to finally get a QT app running (qt-maemo-example from fremantle extras-devel). Based on that experience, I updated the QT wiki page at:
>http://wiki.maemo.org/Qt4_Hildon#Limitations
>
>I hope you guys will make additions and corrections to there, so we have more information easily available.

I believe you (or anybody else) are very welcome to pixel perfect and fine tune the list performances of 
the Qt equivalent widgets if someone creates the missing few hildon widget Qt equivalents.

Best Regards,
Karoliina