[Development] The place of QML

[Иван Комиссаров]

You need users who will use Qt to survive. And those are desktop developers. Show me lot of not "hello world" apps writte using qml. Where are they? On symbian? Maybe in MeeGo? I don't see any on the desktop. But i see Guitar Pro right now which is based on QWidgets.

About O-notations. Article i mentioned shows that Quick-1 showed 90 FPS using QPainter. Why do we need to raize up performance to 250 FPS, if user can't see more than 24 frames per second? Excpecially in static UI. In my IPhone i don't see where i need such a big frame rate. I don't mention games (they need such FPS to freen CPU resource), and i think it really can be useful there. But NOT on the desktop. Almost all advantages of QML are gone there - batteries are big, CPU are fast. Painter works perfectly. And yes, i need _native_ interface here which is done using painter/styles. I don't want to implement 3 different interfaces for each platform. I want to use my old code. And you telling me to throw it away. Why the hell i should do that? First let microsoft deprecate winapi and reimplement whole OS from scratch. Then you can start telling me what to do.
And what about KDE? It is all based on QWidgets. And it took them many years to make stable release for KDE 4 (KDE 4.4 was the first release i could use). You want them to reimplement whole KDE using QML? And spent next 4-5 years fixing bugs that already occured in QWidget stack? No, thanks. Finish QML first, create big declarative item library (with all functionaloty that present in QWidgets, fix all bugs and only then say that painter and widgets are outdated).
Last qt releases (4.8) are crap - they give only bugs. Lot of people still prefer to use 4.7.4 (not me, however). As for Qt5 - even examples from Qt Demo crash. Even "outdated, but stable" widgets. And, which is more important, qt5 release is delayed.

What i'm trying to say - you stop maintaining qwidgets, but giving us promises about "beautiful qml" for 3 (three!!) years. And it is still not here. I don't believe it can replace qwidgets, sorry. In qt6, maybe, but not now. So continue adding new widgets and fixing old bugs, please.

18.05.2012, в 10:29, <marius.storm-olsen at nokia.com> <marius.storm-olsen at nokia.com> написал(а):

Sounds like marketing?

It might be a 'constant' in the grand scheme of big-O notations. However,
if the result is that you can only get 24 fps on low-end HW with large
power footprint vs. 60 fps with HW acceleration, lower power footprint and
leaving the main CPU to do more important tasks, what would you call the
former? That's right, outdated technology. Scene graph is very much based
on what todays graphics cards are optimized for, while QPainter.. well,
it's not. We have gone as far as we could with QPainter, and needed
something new to survive the next 5-10 years. It's not about marketing, I
assure you.

-- 
.marius


On 5/18/12 7:36 AM, "ext Иван Комиссаров" <abbapoh at gmail.com> wrote:

> Btw, you're saying that painter technology is outdated? What speedup
> provides QML scene graph? According to this
> http://labs.qt.nokia.com/2011/05/31/qml-scene-graph-in-master/ article,
> speedup is 2.5 times. As for me, it's just a constant optimization, it is
> not reduces complexity very much, as for me.
> If you say you reduced speed 10 times or 100 - it's the other issue. But
> saying that painter is outdated just because it 3 times slower than new
> qml... sounds like a marketing.
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