[cairo] Mozilla on Cairo

Leon Woestenberg leonw at mailcan.com
Thu Jun 9 14:49:03 PDT 2005

Hello Robert,

Robert O'Callahan wrote:

>On Mon, 2005-05-30 at 22:25 +0200, Leon Woestenberg wrote: <...>
>>Hardware and software limitations usually force us to make tradeoffs,
>>and the correct tradeoff is application-dependent. For avionics you may
>>be able to specify high-end hardware so no tradeoffs are required ... or
>>maybe you don't care about seam artifacts. On the other hand, users want
>>to run Firefox on low-end machines, and in that case speed is most
>>important; below that I think avoidance of seam artifacts is more
>>important than general-purpose antialiasing.
>>I hope we all agree that cairo should give the application developer
>>some control over these decisions.
I agree on all points. The decision is currently limited by the lower 
and upper bounds of what cairo and
libpixman provide.

I suggest that the upper bound on the quality of anti-aliased rendering 
should be hightened given what is possible
with current hardware. This is currently limited by cairo and libpixman.

However, I repeat my earlier statement:

"I do not see why one would want to fall back to FSAA when all the 
information to properly do pixel based coverage (like pixman does),
is available. There must be a way to do this properly, which is 
high-performant as well with current hardware?"

You bias towards FSAA because of a "seam" problem - could you please 
describe this phenomenon? I do remember an earlier
thread on the list - but I cannot find it.

>>[Eventually I'd like to be able to make the tradeoff dynamically ...
>>e.g., do low-quality rendering while animation is happening, and do a
>>high-quality pass when animation stops.]
Good idea. I have been thinking about a two-pass rendering for static 
GUI elements myself: first pass with a
box filter, second pass with weighted filtering.


Leon Woestenberg.

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