[cairo] Mozilla on Cairo

Leon Woestenberg leonw at mailcan.com
Mon May 30 13:25:06 PDT 2005

Hello Robert,

Robert O'Callahan wrote:
> On Sat, 2005-05-21 at 21:42 +0200, Leon Woestenberg wrote:
>>Robert O'Callahan wrote:
>>>On Thu, 2005-05-12 at 00:27 +0200, Leon Woestenberg wrote:
>>>>For things like user interfaces, I would consider FSAA out of the
>>4x oversampling in each dimension gives 16 levels of a pixel coverage
>>estimate for each pixel, which is still a factor of 16 short of 256,
>>which can be achieved with calculating pixel coverage and alpha factor.
> Why is 256-level antialasing absolutely essential for UIs?
"absolutely essential" is subjective.

GUI's are very tightly packed with information. Presenting this 
information in a non-blurred and non-aliased manner is vital.

Given that we have all the information to be presented available,
I would suggest to create high-fidelity graphics output.

Aside from 256-level anti-aliasing, more demanding GUI's need more: 
weighted area filtering instead of unweighted area filtering.

libpixman uses unweighted area sampling (box filter) currently.

A good short read on this are pages 1-3 of this paper:

Platt, K.
Computer graphics techniques and tradeoffs in avionics displays
Proceedings of the 21st Digital Avionics Systems Conference, Volume 2, 
Section 11.A.1, Pages 1-13, October 27th-31st 2002, Irvine, CA, USA
Piscataway, NJ, USA, IEEE, 2002

Agreed, avionics have high demands.

TFT type displays need other filters, back from the ideal sinc()
or Gaussian filter to cone or box type filters.



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