Qtopia coming for Neo1973

Lorn Potter lpotter at trolltech.com
Tue Sep 25 20:36:29 CEST 2007

Dr. H. Nikolaus Schaller wrote:
> Am 25.09.2007 um 17:20 schrieb Dani Anon:
>> But hey I like how you conveniently left unanswered my comment about
>> how the FBUI and DirectFB projects exist solely to remove the X server
>> overhead. Can you explain to me and them why they are wrong and how
>> they have wasted all those months of development to solve a problem
>> that just doesn't exist?
> It exists theoretically but the practical relevance depends on several 
> factors.
> I have done some experiments on the OpenMoko and I believe that the
> framebuffer itself is the slowest part (don't know why). But X11 *is* 
> already
> quite fast.
> I could achieve a lot of speed up in my GUI Framework (yes it is another 
> choice!)
> by double buffering X11 (i.e. drawing offscreen first and then copying the
> modified block in a single bitmap copy command).
> In my GUI toolkit the main speed killer is the missing FPU in ARM 
> processors
> which has to rely on FPU emulation.
> So, why optimize something that already works sufficiently? It is like 
> washing whiter
> than white. But if there is someone who wants to optimize it further - 
> why not?
> So - IMHO - the X11-Overhead is a neglectable problem. And the benefits 
> of X11
> overweight any drawbacks.

There may not be very much performance differences, but there is one 
more drawback of using Xlibs. File size and memory.

Lorn 'ljp' Potter
Software Engineer, Systems Group, MES, Trolltech

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