Probably this bug <a href="https://github.com/googlei18n/noto-fonts/issues/212">https://github.com/googlei18n/noto-fonts/issues/212</a> is related. <div class="gmail_quote"><div dir="ltr">On Tue, Dec 8, 2015, 2:44 PM Khaled Hosny <<a href="mailto:khaledhosny@eglug.org">khaledhosny@eglug.org</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Mon, Dec 07, 2015 at 09:13:23PM +0530, Deepak Jois wrote: > Maybe this is a bit related to Khaled’s question earlier about control > characters inside ligatures, but I wanted to start a new thread. > > When I shape text with Noto Nastaliq, I notice a bunch of zero-width > glyphs generated > > $> hb-unicode-encode U+06CC,U+06C1 | hb-shape notonastaliq.ttf > [HehFin=1+472|TwoDotsBelowNS=0@310,-383+0|sp2=0+0|BehxIni.outS1=0@0,-68+731] > > 1. What is the purpose of these zero-width glyphs? That is something internal to the font, they are not glyphs inserted by HarfBuzz. > 2. If I am rendering the shaped output to a PDF file (for e.g. when > using Harfbuzz with LuaTeX), do I need to care about these zero-width > glyphs at all? How will they affect rendering You should just output the glyph as returned by HarfBuzz, second-guessing it is likely to be wrong. If a character should be invisible HarfBuzz will replace it by the space glyph, so you need not worry about this, unless you really know what you are doing. Regards, Khaled _______________________________________________ HarfBuzz mailing list <a href="mailto:HarfBuzz@lists.freedesktop.org" target="_blank">HarfBuzz@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/harfbuzz" rel="noreferrer" target="_blank">http://lists.freedesktop.org/mailman/listinfo/harfbuzz</a> </blockquote></div>