On Mon, May 11, 2015 at 08:49:48PM +0000, Louis Semprini wrote: > > > > Date: Mon, 11 May 2015 21:35:49 +0200 > > From: [email protected] > > To: [email protected] > > CC: [email protected] > > Subject: Re: [HarfBuzz] how to detect missing glyphs e.g. for font > > substitition > > > > On Mon, May 11, 2015 at 07:56:19AM +0000, Louis Semprini wrote: > > > Or, must Harfbuzz callers first do a complete, separate pass where > > > they run all code points of the input through some kind of mapping > > > routine that uses the fonts' 'cmap' and other tables? The latter > > > would be a shame because it would require the Harfbuzz caller to > > > duplicate a vast amount of the complexity that is nicely hidden in > > > Harfbuzz in their own code. It's also a shame because in most cases, > > > no font substitution would be needed and so it would be inefficient in > > > the average case. > > > > Some HarfBuzz users do that i.e. check the font’s cmap table to see what > > characters it supports and selects fallback fonts for what it doesn’t > > before even calling HarfBuzz. Others rely on HarfBuzz, for example in > > LibreOffice the run is first shaped with the user selected font, then > > any contiguous runs of missing glyphs are reshaped with fallback fonts, > > this have also the advantage of letting HarfBuzz do its normalisation > > which can result in the font supporting more characters than it declares > > in its cmap table. > > That's good to know, but for the second group of users, how do they > detect the missing glyphs? By looking for glyph index 0?
Yes (but as Konstantin said, it depends on what your font functions return for missing glyphs). Regards, Khaled _______________________________________________ HarfBuzz mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/harfbuzz
