Anti-aliasing via GPU

Kohei Yoshida kohei.yoshida at
Thu Dec 13 17:21:38 PST 2012

On 12/13/2012 04:45 AM, Michael Meeks wrote:
> On Thu, 2012-12-13 at 08:51 +0200, Noel Grandin wrote:
>>>> IIRC, Cairo also runs on win32, so why not using it instead of gdi+ ?
> 	We actually shipped a version using the cairo canvas by mistake at some
> stage - that caused serious grief because of a (IIRC now fixed) font
> rendering nasty.
>>> How is cairo's performance against gdi+ on Windows?  Do you know?
> 	Any discussion of performance without profiling is just a total waste
> of time :-)

I was just looking for some casual anecdotal tales, sort of like what 
Noel G gave me.  Since proper profiling of a drawing framework takes at 
least a few days (running various benchmarks under various scenarios, 
and interpreting & writing about the results), I thought a desire to get 
some anecdotes before getting serious was warranted.

I would put very good money on the poor draw / drawinglayer
> performance around rendering large documents being -absolutely-nothing-
> to do with either cairo or VCL, and everything to do with dumb
> algorithmic stupidities caused by layering, and hidden behind some
> otherwise apparently obvious code :-)

So, my interpretation of why Enrico asked about this was more on 
reducing our own drawing layer in favor of using someone else's, to 
reduce maintenance, which to me is a reasonable view.  And I wanted to 
ask about the performance aspect of it to see if that move would or 
would not cause any negative side effort since the performance of the 
drawing layer is pretty darn important to us in general.

We can push pixels at blinding
> speed - but if the real problem is an N^3 in the rendering path in the
> number of objects it's not going to help at-all ;-)
> 	So - where's the profile ?

I would be happy to spend a few days to profile each drawing frameworks 
if you want me to.  But alas, right now I'm soooo loaded with Calc work 
that I may have to wait a year or so to be able to do that.

  more to the point - where is the
> document ? :-) Kohei - I assume this is your nice class diagram /
> documentation ?


  if so - I'd love to have the canonical version of that
> in git / core as a flat odg (flat so revision control is meaningful and
> reasonable small). Far too few people know about your good work there

I'd rather not.  That document is my personal note.  I put that up on my 
site in the hope that someone finds it useful.  But I'm not ready to 
subject that to multiple people editing it, nor am I looking for 
increasing its visibility.

Having said that, if someone else wants to take my class diagram and 
modify it to fit whatever form fits their need & check it into to the 
core repo, I won't be against it.



Kohei Yoshida, LibreOffice hacker, Calc

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