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Month: February 2012

Re: Re: [trinity-devel] Trinity qt4 port?

From: "Timothy Pearson" <kb9vqf@...>
Date: Mon, 13 Feb 2012 14:50:42 -0600
> On Sunday 12 February 2012 02:20:38 Timothy Pearson wrote:
>> These are the exact reasons I stopped to the move to Qt4 and picked up
>> maintinance of Qt3 (now becoming TQt3).  I gave the conversion effort my
>> best shot (which took many, many months of effort) and stopped once it
>> became apparent how extensive Qt4's limitations were (especially in
>> drawing operations and native X11 window handling) and also how buggy
>> Qt4
>> really is.
> May I ask for the benchmarking results? I am seriously interested here as
> I
> think that I can provide you some valuable help here. My fear is that you
> had
> an incorrect benchmark (the experts call that phoronixing) and that your
> decision is because of that on false grounds.
> Especially important is to consider that graphics cards, drivers, what you
> render (widgets vs scenes), which Qt graphicssystem you use seriously
> influences the result. E.g. rendering widgets with raster might be a bad
> idea.
> Cheers
> Martin

I do not have any benchmarks handy at the moment, although this is simply
due to the length of time from those tests to the writing of this message.
 The upshot was that Qt4 is significantly slower when it comes to
rendering raster graphics (as you mentioned), and also when large numbers
of widgets are displayed on-screen.  If I understand some of the Qt
changes, the raster performance was improved somewhat in the latest
versions of Qt4, but I don't know if the other problems were addressed.

As an aside, 3D graphics hardware is not only expensive, it is also one of
the most proprietary and least-understood components in a typical computer
(it also tends to burn out a lot, at least that is my experience with
anything other than an enterprise-grade nVidia Quadro card).  If nVidia
and ATI experienced supply shortages (don't laugh, remember the recent
hard drive scarcity due to flooding in Thailand) I would still need to be
able to use my computers with not-so-great backup graphics hardware, and
possibly without good OpenGL support.

More practically, even slightly sluggish performance is quite noticeable
to power users.  Many applications, upon converting from Qt3 to Qt4,
appeared to slow down noticeably.

These are just my $0.02 and experiences in working with Qt 4.7.  I am open
to looking at Qt4 again once Trolltech fixes the raster graphics problem
for good.