[HarfBuzz] Reply to Luis de Bethencourt

Luis de Bethencourt luis at debethencourt.com
Tue Feb 11 22:00:25 CET 2014 

Hi Robin,

Thanks for the summary. Good luck with your professor. Try to pick his
brain as much as possible. People passionate about a topic love having any
chance to talk about it, so I'm sure he will share a lot of his knowledge.

It is true that documentation about text rendering isn't as good as it
should be, but I don't think is secretly locked in a few selected minds. A
lot of these people manage to find some time to write down papers and give
talks that are really interesting.

Let me know if I can help you with your learning adventure,
Luis


On 10 February 2014 15:37, Robin Skahjem-Eriksen <
robinds at student.matnat.uio.no> wrote:

> Thank you for the link. I shall look at the code once I get some time off
> from my semester workload. Hopefully the course I'm taking this semester
> will improve my C coding skills to better understand the text rendering
> stack.
>
> The only reading I've done so far is the article written by Behdad
> Esfahbod, "State of Text Rendering" along with the docs from the Microsoft
> font resources. I have a link to it in my first mail. I believe Adobe also
> have some documents, but I've been more focused on the specifics of
> multiple caret placements for ligatures formed from vertical glyph stacks,
> so I haven't been able to read everything yet. I recently discovered that
> one of the great teachers at my University is very learned in digital
> typefaces and typography, so I'm preparing myself with some questions I can
> ask him and see how he responds. If I'm lucky, he'll let me pick his brain
> for any deeper knowledge he might have on this subject. The IRC channels to
> watch are #harfbuzz, #fonts and perhaps #freetype on the freenode servers.
>
> The current status of documentation and knowledge about the deeper aspects
> of text rendering seems very sparsely documented and with only a few people
> who actually know every detail of it. I was thinking I should perhaps
> document my studies of this topic and hopefully manage to structure it in
> some way that might serve as a future reference.
>
> Are my assumptions mistaken: Does most of this knowledge only abide in the
> minds of a relatively small amount of people across the world?
>
> -Robin
>
>
> On Fri, Feb 07, 2014 at 12:00:18PM -0800,
> harfbuzz-request at lists.freedesktop.org wrote:
> > Send HarfBuzz mailing list submissions to
> >       harfbuzz at lists.freedesktop.org
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> >       http://lists.freedesktop.org/mailman/listinfo/harfbuzz
> > or, via email, send a message with subject or body 'help' to
> >       harfbuzz-request at lists.freedesktop.org
> >
> > You can reach the person managing the list at
> >       harfbuzz-owner at lists.freedesktop.org
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of HarfBuzz digest..."
> >
> >
> > Today's Topics:
> >
> >    1. Re: Eager CS undergrad thirsty for knowledge about the inner
> >       bowels of typeface rendering. Specifically for supporting
> >       vertical ligature caret definitions. (Luis de Bethencourt)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Fri, 7 Feb 2014 11:42:12 -0500
> > From: Luis de Bethencourt <luis at debethencourt.com>
> > To: Harfbuzz <harfbuzz at lists.freedesktop.org>
> > Subject: Re: [HarfBuzz] Eager CS undergrad thirsty for knowledge about
> >       the inner bowels of typeface rendering. Specifically for supporting
> >       vertical ligature caret definitions.
> > Message-ID:
> >       <
> CAPA4HGV0_39Ta2Zt0vcHmfegng4zM6iNDEhcpaBf9FeUdtkdGg at mail.gmail.com>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Hello Robin,
> >
> > I am in the opposite place you are. I come from the Computer Science
> world
> > and want to learn more about Typography and how computers handle it. We
> > should help each other!
> >
> > Where did you learn all the typography/font concepts and terms you know?
> > Recommend any good resource to learn this?
> > Which is this IRC channel you mentioned?
> >
> > If you want to play with Harfbuzz, I recommend this example code:
> > https://github.com/lxnt/ex-sdl-freetype-harfbuzz
> >
> > Your idea of having a dissection of font files similar to the famous
> > dissection of executable files is a really good one.
> > What do you people in the list thing is a good format to start such a
> > project?
> >
> > Cheers,
> > Luis
> >
> >
> > On 29 January 2014 18:21, Robin Skahjem-Eriksen <
> > robinds at student.matnat.uio.no> wrote:
> >
> > > Thanks for link. I shall make sure to read up on that.
> > > I am have slowly started the process of writing some software for
> Tibetan
> > > writing. I thought about how to handle the complex caret behaviour,
> when
> > > people on IRC stated that I should look into getting that done deeper
> in
> > > the text rendering stack.
> > >
> > > Do you know if Graphite currently support caret placements for
> ligatures
> > > which have been transmuted from a stack of glyphs?
> > >
> > > -Robin
> > >
> > >
> > > On Wed, Jan 29, 2014 at 02:37:18PM -0500, Ed Trager wrote:
> > > > Hi, Robin,
> > > >
> > > > You might also want to read up about Graphite:
> > > >
> > > >
> > >
> http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_home
> > > >
> > > > I believe that Graphite has more sophisticated support (compared to
> > > > OpenType technology) for caret placement for complex scripts such as
> > > > Tibetan.  On the flip side, in comparision to OpenType, Graphite is
> not
> > > > widely used.
> > > >
> > > > - Ed
> > > >
> > > >
> > > > On Mon, Jan 27, 2014 at 7:32 PM, Robin Skahjem-Eriksen <
> > > > robinds at student.matnat.uio.no> wrote:
> > > >
> > > > > I have started to investigate into the matter and I find that
> there is
> > > > > very sparse information readily available. Microsoft had a very
> > > interesting
> > > > > document, which I have been trying to understand:
> > > > > http://www.microsoft.com/typography/OpenTypeDev/tibetan/intro.htm
> > > > > In the section "Examples of Tibetan" (bottom of document), the
> first
> > > > > example shows how a sequence of eight code points are strung
> together
> > > to
> > > > > form a Tibetan "syllable". It's not really a syllable. It's called
> a
> > > > > tsheg-bar in Tibetan and a Tibetan word can consist of multiple of
> > > these.
> > > > > Anyways, all the code points from the second one up to and
> including
> > > the
> > > > > fourth one are as far as I can tell formed into a ligature. I have
> > > opened
> > > > > the MS Himalaya font in Fontforge and seen that this ligature is
> > > defined as
> > > > > "tibSa_Ga_Rata_Shapkyu" in a location outside of the Unicode
> address
> > > space.
> > > > >
> > > > > Now, if a user is to work with Tibetan text like any other user of
> a
> > > roman
> > > > > script language, the user of Tibetan script would be very
> > > disappointed. The
> > > > > reason for this is that it is impossible to place the caret and
> select
> > > > > individual characters in this ligature. As of now, you can only
> select
> > > the
> > > > > entire stack as a whole selection. This is partly because the
> glyphs
> > > have
> > > > > been transmuted into a ligature, but perhaps also because there
> seems
> > > to be
> > > > > no definitions of vertical caret ligatures anywhere.
> > > > >
> > > > > How would one go about defining such an important feature? Should
> this
> > > be
> > > > > implemented in the font? Should it be implemented in the software
> that
> > > > > handles the type face? Or perhaps both? While digging through the
> MS
> > > > > Himalaya font, I found that there is a value for a Ligature Caret
> > > Count.
> > > > > What is this value supposed to be used for? For the ligatures that
> are
> > > > > supposed to represent stacks of multiple glyphs, the Ligature Caret
> > > Count
> > > > > had values up to 4, which I hope can mean that the font itself
> > > contains the
> > > > > information I am looking for. Is my assumption correct?
> > > > >
> > > > > Also. I am highly willing to learn more about the inner bowels of
> > > typeface
> > > > > rendering. I have taken a course on Computer design and understand
> how
> > > > > everything are bits and how Asssembly language and C handles this.
> I
> > > also
> > > > > understand the general idea about Unicode and how this is defined
> on a
> > > low
> > > > > level. I've also understood that fonts are basically B?zier curves
> > > which
> > > > > are rasterized to the screen buffer. There is still a lot of this
> > > process
> > > > > which I still find very murky, so if anybody knows any in depth
> reading
> > > > > material, I would be very happy to start reading those. I have read
> > > State
> > > > > of Text Rendering by Behdad Esfahbod, which was a great overview
> of the
> > > > > text rendering stack. But I would really like to get more in depth
> > > > > understanding of each layer in the stack.
> > > > >
> > > > > I would really like to also learn more about Harfbuzz and how to
> work
> > > on
> > > > > it. I would really love to spend some time working on it, if I am
> at a
> > > > > level where my code submission would be acceptable to the
> standards of
> > > this
> > > > > project. Is there any documentation for Harfbuzz? I've taken a
> quick
> > > glance
> > > > > at the source code and run some scripts and make commands, but I
> > > honestly
> > > > > don't know what's going on. Why are the C files named .cc and some
> of
> > > the
> > > > > header files named .hh? I can recognize some font lingo and have a
> > > slight
> > > > > understanding of what might be going on, but it would be really
> > > helpful to
> > > > > have something like this for an Openfont file:
> > > http://imgur.com/a/JEObT#0.
> > > > > I must also say that I have no idea of what harfbuzz is supposed
> to do
> > > and
> > > > > how I test or use it once it's compiled. I've tried running some
> shell
> > > > > scripts and bin files that were compiled, but I really have no
> clue.
> > > > >
> > > > > Is there somewhere I can learn how to get a handle on
> understanding the
> > > > > technicalities of the Harfbuzz project and learn what I need to
> start
> > > > > contributing?
> > > > >
> > > > > Sincerely,
> > > > > Robin Skahjem-Eriksen
> > > > > _______________________________________________
> > > > > HarfBuzz mailing list
> > > > > HarfBuzz at lists.freedesktop.org
> > > > > http://lists.freedesktop.org/mailman/listinfo/harfbuzz
> > > > >
> > > _______________________________________________
> > > HarfBuzz mailing list
> > > HarfBuzz at lists.freedesktop.org
> > > http://lists.freedesktop.org/mailman/listinfo/harfbuzz
> > >
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL: <
> http://lists.freedesktop.org/archives/harfbuzz/attachments/20140207/9d39909e/attachment-0001.html
> >
> >
> > ------------------------------
> >
> > _______________________________________________
> > HarfBuzz mailing list
> > HarfBuzz at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/harfbuzz
> >
> >
> > End of HarfBuzz Digest, Vol 92, Issue 5
> > ***************************************
> _______________________________________________
> HarfBuzz mailing list
> HarfBuzz at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/harfbuzz
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/harfbuzz/attachments/20140211/82ed2702/attachment-0001.html>

More information about the HarfBuzz mailing list