Re: Bug: Reloading Font

[Khaled Hosny <khaledhosny@eglug.org>]

On Sun, Oct 13, 2013 at 12:39:32AM +0200, Hans Hagen wrote:
> On 10/12/2013 12:19 PM, Khaled Hosny wrote:
> 
> >The problem is that OpenType is hard, you already know that. ConTeXt
> >will never be able to dedicate enough resources to catch up with
> >development, so it makes much sense to reuse the efforts of other free
> >software projects. HarfBuzz is used by much more software projects than
> >what XeTeX was using before (Android, Mozilla, Chrome, LibreOffice,
> >Pango, EFL, to name few), so it is here to stay. That being said, the
> 
> I bet that previous libs and whatever also have that impression ..

I don’t think so, ICU Layout Engine was only used by Java, OpenOffice
and XeTeX (as far as free software is concerned), and even for XeTeX it
was not adequate and had to be patched. This is different from HarfBuzz,
which is a mature piece of code that have been developed and used over a
long time and is seeing a wide adoption, my impression is that HarfBuzz
is here to stay, just like FreeType; so many people are investing in it.

> well, in the end I think that open type will fade away too into
> something else as its design is sort of a compromise. The dev cycles
> get smaller each year, the claims for 'being the final solution' get
> more, who can predict ...

I doubt that OpenType is going anywhere, not matter how bad it is, the
industry has invested so much into it and switching to any completely
new solution will be prohibitively expensive.

> >switch in XeTeX did not affect user documents that much (apart from
> >fixing bugs and supporting more OpenType feature, but so does ConTeXt
> >all the time). However, I’m not proposing that LuaTeX be dependant on
> >HarfBuzz or FreeType, but have an optional font loader and shaper that
> >need not even be managed by LuaTeX team.
> 
> once we have a more or less standardized lib loader (the swiglib
> project) one can use such libraries, i.e. there is no need to have
> something more in the luatex core; after all, it all boils down to
> passing info around; anything hard plugged into to core (even
> options) will be hard to fight if one wants something else

An external module is fine by me, I’m not concerned about LuaTeX itself
since even the current loader is not integrated, I’m rather concerned
about the ability to use the new loader and shaper with ConTeXt.

> at that point i can look into for instance freetype and see if a
> better loader can be made, who knows ... for me loading and shaping
> are different things
> 
> >Fonts change, font formats evolve, Knuth-style stability is not really
> >achievable, unless one freezes the source code and the fonts forever,
> >and you can do this with external libraries, too; TeX Live is
> >self-contained, just take a snapshot and freeze it forever, and it
> >should be buildable as long as there are C(++) compilers.
> 
> well, practice ... one also needs to freeze the operating system then
> 
> but I'm not claiming that long term stability; there was a time that
> tex was a big system, but nowadays the tds tree is relatively small;
> unless something magic happens, i think that at some point the
> complexity of all these big things will explode (one can according
> to the evangelists get a ruby on rails app up and running in minutes
> ... but try to update one a few years later) ... with respect to
> tex: the source tree/build is not trivial (how many folks know all
> ins-and-outs?) and it makes me already feel quite dependent .. it's
> the instability of the whole eco system that bothers me
> 
> well, the formats don't evolve that much, at least not with respect
> to what we need in tex ... most features are rather generic, but tex
> user demands evolve and those will always influence matters; also,
> in the (context) machinery at some point i want to play with other
> approaches and then the only thing that matters is having data
> available (we already have some par optimizing code in place for
> instance)
> 
> (i'm more worried about inconsistencies and a mess in fonts than in
> the opentype standard ... many characters / scripts / languages have
> well properties, so in fact designers could do with predefined sets
> of features and rules ... sort of the reverse of making shapes and
> then the features: instead of for each font reinventing the wheel,
> choose a set of logic, make shapes etc ... positioning is probably
> most of the issue then; but that's another disucssion)
> 
> >There are already few parts of OpenType that I’m not able to use in my
> >fonts for years because they break the fonts with LuaTeX horribly. I
> >understand the priorities of the team, that is why I think that
> >offloading font support is beneficial to everyone.
> 
> break in what sense? what features (just curious) ... anyway,

The mark filtering sets we discussed few years ago, for instance; I had
to redo the whole font in a much more complex way with few more
thousands of glyphs to avoid using them so the font remains usable with
ConTeXt, and I still get crashes every now and then that I stopped
bothering with reporting them.

> there's always xetex as alternative -)

Except I can’t use it :) even with MkII as there is zero support for
XeTeX’s (rudimentary) RTL model.

> (unless you're referring to wanting to use the microsoft word math
> renderer trickery -)

I never set math actually :) unless I’m testing a math font, but I can use
plain for that.

> >>One important aspect is that when using tex, one also wants
> >>flexibility and control and so a font system will have hooks and
> >>such. Using a mixed library / lua / tex approach would become pretty
> >>complex. Sure, the current lua code is not trivial either but can
> >>probably be simplified over time once settled down. One reason for
> >>me not to use xetex (plus its libs) is inflexibility. If we hadn't
> >>started luatex I might as well have opt out of tex altogether,
> >>especially because only with luatex i can do some of our projects
> >>within acceotable bounds (dev time, speed of machinery,
> >>flexibility).
> >
> >I don’t think much of LuaTeX’s flexibility (or XeTeX’s inflexibility) is
> >related to the OpenType layout engine used.
> 
> I can imagine cases where things happen before shaping that have to
> be taken into account when shaping, and also that shaping signals
> things to be done later ... once we start thinking out of the box
> ... but, i don't see a problem in having multiple shapers (dozens)
> as long as (in context) they can cooperate, be isolated, controlled,
> etc. My main point is that I don't like a hard coded choice in
> luatex (also performance wise). The current core components still
> resemble tex.

I absolutely agree. All I wanted to know is whether ConTeXt can consider
integrating an optional different font machinery, so to not waste time
on something that will be of little use to me.

Regards,
Khaled
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