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.
Tim