[Pixman] Plan to release final development version before stable branch

[Bill Spitzak]

On Tue, Dec 15, 2015 at 1:29 AM, Oded Gabbay <oded.gabbay at gmail.com> wrote:

> On Sat, Dec 12, 2015 at 9:10 PM, Bill Spitzak <spitzak at gmail.com> wrote:
> >
> >
> > On Sat, Dec 12, 2015 at 10:37 AM, Oded Gabbay <oded.gabbay at gmail.com>
> wrote:
> >>
> >> On Sat, Dec 12, 2015 at 8:34 PM, Bill Spitzak <spitzak at gmail.com>
> wrote:
> >> > On Fri, Dec 11, 2015 at 4:15 AM, Oded Gabbay <oded.gabbay at gmail.com>
> >> > wrote:
> >> >>
> >> >> On Thu, Dec 10, 2015 at 11:19 PM, Bill Spitzak <spitzak at gmail.com>
> >> >> wrote:
> >> >> > Can you include my patches to fix the filtering? They have been
> >> >> > posted
> >> >> > for a
> >> >> > long time now.
> >> >> >
> >> >> > The last patch makes GOOD/BEST use filtering for scaling images
> down.
> >> >> > This
> >> >> > matches the current Cairo behavior and would allow Cairo to use the
> >> >> > pixman
> >> >> > backend rather than doing an image fallback for any image scaling
> >> >> > smaller
> >> >> > than .75. It also contains a bunch of minor optimizaion and filter
> >> >> > selection
> >> >> > tweaks that makes the output somewhat better than current Cairo.
> >> >> >
> >> >> Hi Bill,
> >> >>
> >> >> Unfortunately, I don't see anyone reviewed your patches, and from
> what
> >> >> I heard, those are quite significant changes.
> >> >>
> >> >> It's a shame you didn't bring this up when I did the first
> development
> >> >> release 4 months ago. Then we had enough time to check and test it.
> >> >> I'm quite hesitant of including such changes right before the final
> >> >> development version, even with a review.
> >> >
> >> >
> >> > I did send email on May 22, 2015, in response to your comments.
> >>
> >> That's strange, because I only started working on pixman during June of
> >> 2015...
> >
> >
> > You are right. That was just a general email I sent trying to get
> somebody
> > to look at the patches. Searching in the history I found 3 of these.
> >
> >>
> >>
> >>
> >> >
> >> >> I suggest that you try to contact one of pixman's veterans (Soren,
> >> >> Siarhei, Matt, Pekka, Ben) offline and ask them nicely to at least
> >> >> skim over the patches and give a high-level opinion about the series.
> >> >
> >> >
> >> > These were discussed with Soren before. He disagreed with my previous
> >> > version because I changed to a single filter calculation rather than
> his
> >> > pair of filters being convoluted. This version preserves the pair of
> >> > filters, with some fixes of bugs that caused artifacts in the
> resulting
> >> > filters. I'm sending email directly in case they are not reading the
> >> > pixman
> >> > list.
> >>
> >> Could you send me those emails ?
> >
> >
> > I forwarded the big one from him and my response. The patches I have had
> > since then I believe address his concerns and preserve the 2-filter
> > convolution api, they are just bug fixes and some efficiency changes.
> >>
> >>
> >> >>
> >> >>
> >> >> Also, check if you need to rebase the patches against current pixman
> >> >> and if so, maybe send the series again. It might stir up a
> discussion.
> >> >
> >> >
> >> > The patches applied to the newest version without any conflicts and my
> >> > test
> >> > programs still work. I have resent them to the pixman mailing list.
> >> >>
> >>
> >> Great!
> >>
> >> >>
> >> >> I'm willing to review them in terms of correctness and code style,
> but
> >> >> I'm not veteran enough in pixman to give an opinion on the underlying
> >> >> changes (which is the most important issue).
> >> >
> >> >
> >> > Anything would be great.
> >> >
> >> > I believe these work well and have been using them for a while. This
> >> > would
> >> > allow the removal of redundant code in Cairo, and would allow 2-pass
> >> > filtering to be done at some point in the future, which would really
> >> > improve
> >> > pixman performance.
> >> >
> >> ok, I'll try to take a look next week or so.
> >>
> >> Oded
> >
> >
>
> Hi Bill,
>
> I read most of the emails you sent me and I cleared time tomorrow to
> review your patches.
>
> Having said that, IMHO, I believe it would be too risky to merge them
> into the final development release. This is due to a combination of
> two things:
>
> A. This release, although it is a "development release" is used by
> current distributions (fedora 22,23, ubuntu, debian). That's because
> there was a big gap in the release schedule earlier this year.
>
> B. The changes here affect users of pixman and cairo, by changing the
> way pixman behaves. So even if your patches are perfect, and the
> result is a better pixman, we need to give time to users (and to
> cairo) to adapt to it. This can only be done in master branch, not in
> stable branches.
>
> So, what I intend to do is to:
>
> A. Review your patches and if necessary, ask you to fix issues.
>
> B. Assuming no objection will be made by other pixman developers
> during the next couple of weeks, I will merge the patch series into
> master *after* I branch out the 0.34 release.
>
> That way, the patch series will be included in the future development
> releases that will be packaged inside "testing" distributions, such as
> fedora rawhide and debian unstable, and thus we will have time to
> receive feedback from users about the changes.
>
> I hope this is accepted by you and by everyone else. If not, please tell
> me.
>
> Thanks,
>
>        Oded
>

I am fine with this all being for the next release and will be happy to
answer any questions.

I would like to know what a compile-time test for whether libpixman is this
next release or not, and a run-time test to see if X (using both xlib and
xcb) is using this next release of pixman. This will allow code to be added
to Cairo to automatically send the filtering to pixman when possible, and
hopefully get that added at the same time this is supported in the pixman
release.
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