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<div class="moz-cite-prefix">I don’t see any reason why beginning a
GSUB input sequence with ZWJ should not be valid, but that isn’t
the same thing as implying that you might not run into problems in
particular OTL implementations.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">ZWJ and other formatting control
characters with representative glyphs — properly only displayed in
editing environments, not in text presentation — should be
available to GSUB, but then suppressed from the resulting glyph
string for GPOS and display purposes. That behaviour is mostly
reliable in complex script shaping engines, but it is possible
that the path emoji take in some environments may run into
unexpected issues with some part of this procedure.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">JH<br>
</div>
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</div>
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<p>An interesting discussion about glasses emoji is taking place
in the Unicode public mailing list.</p>
<p><br>
</p>
<p><a class="moz-txt-link-freetext" href="https://corp.unicode.org/pipermail/unicode/2022-October/date.html">https://corp.unicode.org/pipermail/unicode/2022-October/date.html</a><br>
</p>
<p><br>
</p>
<p>Thinking about this, earlier this morning here in England I
adapted one of my own fonts to add some additional glyphs to
run a test, and it worked. I used the High-Logic FontCreator
program to make the font and Serif Affinity Publisher to run
the test.</p>
<p><br>
</p>
<p>The font that I adapted is the Mariposa.otf font that is
available from the following web page, though in fact I
started with a copy of the unpublished High-Logic project file
for the font.</p>
<p><br>
</p>
<p><a class="moz-txt-link-freetext" href="http://www.users.globalnet.co.uk/~ngo/mariposa_novel.htm">http://www.users.globalnet.co.uk/~ngo/mariposa_novel.htm</a><br>
</p>
<p><br>
</p>
<p>To the font I added glyphs for three Unicode characters and
for one unmapped glyph.</p>
<p><br>
</p>
<p>U+200D ZERO WIDTH JOINER though I used a wide visible glyph
design</p>
<p><br>
</p>
<p>U+1F453 EYEGLASSES</p>
<p><br>
</p>
<p>U+1F469 WOMAN</p>
<p><br>
</p>
<p>unmapped ceyeglasses, a copy of the glyph used for
eyeglasses, moved 2048 font units to the left and the glyph
having zero advance width.</p>
<p><br>
</p>
<p>Within the liga table I added the following line.</p>
<p><br>
</p>
<p> sub uni200D u1F453 -> ceyeglasses;</p>
<p><br>
</p>
<p>that is, for "combining eyeglasses".</p>
<p><br>
</p>
<p>Please note that the substitution starts with a ZERO WIDTH
JOINER</p>
<p><br>
</p>
<p>In the test in Affinity Publisher I used the Glyph Browser to
enter the three characters</p>
<p><br>
</p>
<p>U+1F469 U+200D U+1F4F3</p>
<p><br>
</p>
<p>and the result displayed was of a woman wearing the
eyeglasses as the display was of the glyph for WOMAN with the
glyph for ceyeglasses superimposed upon it.</p>
<p><br>
</p>
<p>So if it is valid to use a glyph substitution with a leading
ZWJ in this way then the issue appears to be solved.</p>
<p><br>
</p>
<p><span style="display: inline !important;">Is it valid to use
a glyph substitution with a leading ZWJ in this way please?</span><br>
</p>
<p><br>
</p>
<p>One could go further with a sequence also involving a pink
square and a large circle to produce stylish large round pink
rimmed glasses for the lady to be wearing.</p>
<p><br>
</p>
<p>Indeed the technique could be adapted so that the lady is
also wearing a U+1F452 WOMANS HAT in a stylish purple colour.</p>
<p><br>
</p>
<p>William Overington</p>
<p><br>
</p>
<p>Friday 14 October 2022</p>
<p><br>
</p>
<p><br>
</p>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
John Hudson
Tiro Typeworks Ltd <a class="moz-txt-link-abbreviated" href="http://www.tiro.com">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.
__________
EMAIL HOUR
In the interests of productivity, I am only dealing
with email towards the end of the day, typically
between 4PM and 5PM. If you need to contact me more
urgently, please use other means.</pre>
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