Re: Integer pixel operations for gtk+?

[Rob Taylor <rob taylor codethink co uk>]

As I just pointed to Koen on IRC, there's some nice code in Cairo for
fast double-to-fixed conversion [1]. This might mitigate that slowdown.

Thanks,
Rob Taylor

[1]
http://gitweb.freedesktop.org/?p=cairo.git;a=blob;h=fe6c2dc3ee545442286aef3e3291a24dde39733c;hb=eec62c297589ca20f4128c889ecad9e96736a07f;f=src/cairo-fixed.c

Matt Hoosier wrote:
> I don't have the work on-hand any more, but a colleague of mine tried
> just this a few months ago.
> 
> The results (according to gtk-theme-torturer exercising a theme which
> used pixmaps) were somewhat disappointment. If I remember correctly,
> there is currently only a small bit of non-integer math remaining in
> pixops.c (calculation of the filter, or something like that). At the
> time, our speculation was that the overhead to cast the floating point
> inputs into fixed-point was dominating any savings to be had from
> avoiding this small amount of software FP emulation.
> 
> On 2/10/07, Koen Kooi <koen dominion kabel utwente nl> wrote:
> [also posted to openmoko-devel, but I'm too stupid to figure out how to mix&match gmane
> nntp and regular email]
> 
> 
> Hi,
> 
> A few years ago Phil Blundell made patch[1] to speed up pixel operations (scale, blend,
> rotate, etc) a lot for systems without a floatingpoint unit. Years of gtk+ developer
> desinterest have let the patch bitrot a fair deal.
> In order to get the ball rolling again I updated the autotools bits in the patch and
> adjusted the indices so it applies to the .c files as well. What's left is updating the
> functions and their arguments to catch up with several years worth of development.
> This patch would speed up the GUI on openmoko based systems a lot, since it's using quite
> a lot if pixmaps.
> 
> I've heard that the openmoko team also tried sapwood, but couldn't get it to work properly
> because it's a) entirely undocumented and b) only supports 1 bit alpha
> 
> Any heroes that want to give a shot at updating the pixops patch?
> 
> regards,
> 
> Koen
> 
> [1] http://bugzilla.gnome.org/show_bug.cgi?id=90621
> 
>>
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