[Development] Review for new widget module [your advices are needed]

[Konstantin Tokarev]

17.10.2017, 15:05, "Shawn Rutledge" <shawn.rutledge at qt.io>:
>>  On 14 Oct 2017, at 09:33, iman ahmadvand <iman72411 at gmail.com> wrote:
>>
>>  Hi everyone.
>>
>>  Before I send some code base on codereview and decide whether my implementation meets the requirements, I just want to know your thoughts about design decision for the new module I’m trying to add to Qt Play ground.
>>
>>  So as you probably guessed my plan is to developing a new widget module (which I’m going to name it MaterialWidgets) for Qt, a modern collection of widgets that should have the same look and feel on all platforms. All the GUI parameters and styles are taken from material style guide line(https://material.io/guidelines). You can think of MaterialWidgets as the MaterialStyle in QML design but in pure C++.
>>
>>  Here is a few things to clarify:
>>  1.Why someone need to use material styled widgets in Qt?
>>  There are a bunch of app out there that need this to be available on widgets so they can easily take the benefit of newly added widget set.
>>
>>  2.Why a new widget set? why just no to use already built-in styles?
>>  Material widgets are going to be a special set of controls which has animations by default,
>
> Animations need to be done on the GPU, IMO, and the scene graph is a fine vehicle for that. If you are thinking of doing animations on the CPU with QPainter, I think that is a waste of CPU cycles, and you might have trouble making it smooth enough anyway.

BTW in Qt 4 times QPixmap was accelerated on some platforms, so it was possible to make such widget animations fast...

>
> And that is one reason (among others) I think it’s a good idea to stabilize the scene graph API with the goal of eventually making it public: we could try to build a widget style which uses the scene graph for rendering. (Disclaimer: I haven’t tried, and probably widgets would need a lot of re-architecting to standardize that way of styling. But wouldn’t it be nice?)
>
>>  and GUI parameters are differs from built-in QtWidgets. for an example material style has a component called ContinuousSlider which has two sub component Thumb and Track and two state On(value == 0) and Off(value != 0) and a color palette for each state, so doing this with styles can't be done unless we change the enumerators and maybe more!
>
> Maybe it’s still worthwhile to try though, and see just how much API change is really needed.
>
> QSS exposes the ability to style sub-components which aren’t otherwise exposed in the API, after all. (These pages explain it a bit:
>
> http://doc.qt.io/qt-5/style-reference.html#sliders
>
> http://doc.qt.io/qt-5/stylesheet-reference.html
>
> http://doc.qt.io/qt-5/stylesheet-examples.html#customizing-qslider )
>
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-- 
Regards,
Konstantin