[Pixman] [PATCH 07/15] pixman-filter: Speed up the BOX+BOX filter

Bill Spitzak spitzak at gmail.com
Fri Jan 8 10:53:02 PST 2016

On Thu, Jan 7, 2016 at 11:44 PM, Pekka Paalanen <ppaalanen at gmail.com> wrote:

> Please keep in mind that the filters GOOD and BEST have been as is for
> a long long time, AFAIU, so changing their behaviour now is likely not
> a good idea. They are no longer "a good filter" and "whatever best
> filter", but "the specific filter called GOOD" and "the specific filter
> called BEST", in lack of documentation saying otherwise.

Both GOOD and BEST are identical to BILINEAR in the current version of
Pixman. Therefore anybody relying on the current behaviour can achieve it
by using BILINEAR. In addition GOOD is unchanged for any scales larger than
.75 or for a scale of exactly .5.

Also despite their names, bilinear in no way would be considered "good" or
"best" by any sane person. We should not add illogical names (like NEW_GOOD
or whatever) just because of paranoia over back-compatibility. It is also
highly desirable that the default actually be "good", this cannot be done
unless GOOD is changed, or the default is changed to "NEW_GOOD".

This change was made to Cairo over a year ago with no complaints (except
for speed issues, which this patch is necessary to solve by moving the fix
from Cairo to Pixman). Lets get out of the dark ages, and stop doing things
that are making open source desktops a laughingstock.
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