On Tue, Apr 23, 2013 at 10:00:26AM +0900, suzuki toshiya wrote: > Dear Khaled, > > Khaled Hosny wrote: > > On Sat, Apr 20, 2013 at 10:49:26AM +0100, Jonathan Kew wrote: > >> On 19/4/13 22:13, Behdad Esfahbod wrote: > >> > >>> - What should HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES do to variation > >>> selectors? Right now they do not become visible no matter what. Is it > >>> relevant whether the variation selector was actually used during glyph > >>> lookup > >>> or not? > >> Yes, I think it's relevant. A variation selector that was used > >> during glyph lookup has (in a sense) become "visible", manifested as > >> a particular choice of glyph. I don't think it should -also- appear > >> as a separate glyph, even in a "show invisibles" mode. In effect, > >> the <base, VS> pair has been ligated - it's just a "ligation" that's > >> handled by the cmap instead of GSUB. > > > > But this can be said about many other control characters, ZWJ or ZWNJ > > for example, they have a visual effect. > > > > IMO PRESERVE_DEFAULT_IGNORABLES should simply show any default ignorable > > character that is being removed from the output not as a result of > > OpenType glyph substitution. One use of such feature (the only use?) is > > to make visible all characters that has mysterious effects on the output > > so they can be easily checked/edited, and I can see variation selectors > > benefiting from this just like any other default ignorable. > > I think the requirement to make visible all characters is reasonable, > but I'm not sure PRESERVE_DEFAULT_IGNORABLES is the appropriate place > to serve the request. For example, if ZJW or ZWNJ should be displayed > visibly, various spaces (e.g. U+2000 - U+200B) are not expected to be > displayed with clearly different glyphs?
That is certainly valid point, but HarfBuzz already has PRESERVE_DEFAULT_IGNORABLES, so applying it to variation selectors IMHO makes it consistent. Regards, Khaled _______________________________________________ HarfBuzz mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/harfbuzz
