[cairo] On cairo-quartz being supported (ATSUI vs. CGFONT)

Carl Worth cworth at cworth.org
Wed Mar 26 12:32:28 PDT 2008

On Wed, 26 Mar 2008 14:52:52 +0430, Behdad Esfahbod wrote:
> On Tue, 2008-03-25 at 22:19 -0400, Vladimir Vukicevic wrote:
> > Worst case, we may just have to punt on the whole supported-quartz for
> > 1.6 thing (sadly -- maybe just fonts?), because depending on the size
> > of the issue I'm not sure I'll have time to fix everything quickly.
> > The issue is just with unantialiased text though, so I'm hoping that
> > it'll be fixable in a straightforward fashion.
> These kind of bugs can be fixed later.  I doubt that these affect the
> API.

Right. In the past I've set two things as requirements for a backend
to be "supported"

   1. We feel comfortable promising that the API is stable

   2. There are no failures in the test suite

The first point is definitely very strict, but the second point is a
little fuzzier. For example, when we first marked the win32 backend as
"supported" there were still a couple of test suite failures, and even
with the core image backend we still to this day have a few "expected
failure" tests in the test suite.

So there's some judgment call to be made as to the severity of any
problems in the test suite. Obviously, no failures at all would be
preferable, but we're never going to achieve perfection, so we
shouldn't insist on it, (otherwise we might never release anything).

Instead, I think what we need is a certain level of comfort that
things will generally work, (that is, perhaps a case can be made that
what's being tested by a specific test is obscure and unlikely to be
hit by users---the current cairo-ps failure on miter-limit is an
instance of this, for example). But of course that's subjective, so it
requires some judgment.

What we do need, I think, is a commitment from the maintainers that
what is embodied in the test suite is "correct", and if any user
encounters a significant deviation from that, then effort will be put
into fixing it. What I would never want is some backend maintainer
having an attitude of, "Oh, my backend doesn't work that way---it
draws something different in that case.". (And to be clear, I don't
have any concern about Vladimir's attitude as a maintainer. He has
shown a remarkable amount of dedication toward making cairo robust and
reliable across its various backends.)

Really, the promise of support from an enthusiastic and responsive
maintainer is the most important thing a user could want from that
"supported" label. And there's obviously nothing the test suite can do
to guarantee that.

So, Vladimir, with those ideas in mind, what's your opinion on the
state of the ATSUI vs. CGFONT backends? My impression is that you'll
be much more enthusiastic about responding to CGFONT rather than ATSUI
problems in the future. So I'd be quite nervous about marking the
ATSUI code as supported, but I could feel quite comfortable marking
the CGFONT code as supported if you feel the results are "close

Maybe I should go run the cairo-quartz test suite and look at the
images myself. Where can I find the current cgfont work?

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