<div dir="ltr"><div dir="ltr">On Tue, Dec 12, 2023 at 11:51 AM John Hudson <<a href="mailto:john@tiro.ca">john@tiro.ca</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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<p>I proposed that to the OT developer list a long while ago, and
recall that Kamal had a similar idea, initially in terms of
handling Unicode decompositions such that fonts would not need
precomposed diacritics. At the time, Microsoft thought it unlikely
to get traction, as it implied significant engineering for unclear
benefit, but perhaps the benefit is clearer now? As you say, being
able to decompose a Unicode character to an arbitrary sequence of
glyphs is very useful for Arabic, and by-passes the need to handle
such decompositions in GSUB prior to other shaping. <br>
</p>
<p>I suppose the question is whether there is a significant benefit
to doing this outside of GSUB? — or, indeed, if there might be a
reason it would be preferable in GSUB?</p>
<p>The inconsistency in dot handling in different joining forms of
some Arabic characters means that one doesn’t always want to
up-front decompose some characters to base grapheme and combining
dots, but those could be excluded from the cmap and passed to GSUB
form decomposition in the joining form features. But that being
the case, why not do it all in GSUB?</p></div></blockquote><div>Thanks John. The main benefit in my opinion is not allocating a gid to every precomposed Unicode character, most of them Latin. The Arabic use-case is extra.</div><div> </div><div>b</div><div><br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
<p>JH<br>
</p>
<p><br>
</p>
<div>On 2023-12-12 9:04 am, Behdad Esfahbod
wrote:<br>
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<blockquote type="cite">
<div dir="ltr">Thank you everyone for the very productive meeting.
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<div>I like to also bring this issue up. If there is interest, I
can work on it. I wrote in my reply to Peter earlier:</div>
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<div>
<div><i>This reminds me of another idea we discussed in, I
think, 2019, from Monotype to introduce a `cmap` subtable
that would map individual characters to sequences of
glyphs. Then the pre-composed Unicode characters wouldn't
need to have their own glyphs. Back then we dropped the
idea for backwards-compat reasons. But maybe we can pick
it up now?</i></div>
<span style="color:rgb(80,0,80)">
<div><br>
</div>
<div>This is very useful for Arabic as well...</div>
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</span>
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<div dir="ltr" class="gmail_signature">behdad<br>
<a href="http://behdad.org/" target="_blank">http://behdad.org/</a></div>
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<pre cols="72">--
John Hudson
Tiro Typeworks Ltd <a href="http://www.tiro.com" target="_blank">www.tiro.com</a>
Tiro Typeworks is physically located on islands
in the Salish Sea, on the traditional territory
of the Snuneymuxw and Penelakut First Nations.
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