On 09/03/2012 03:11 AM, Harshula wrote: > On Wed, 2012-07-25 at 16:49 -0400, Behdad Esfahbod wrote: >> On 07/25/2012 03:17 PM, Harshula wrote: >>> >>> Here are more details about the problem. The new shaper renders කො >>> (ko) incorrectly with FreeSerif and LKLUG fonts but renders correctly >>> with Bhashitha font (IIRC, originated from Windows). The old shaper >>> renders the string correctly using all three fonts. >>> >>> String: කො >>> Unicode Sequence: <U+0D9A,U+0DDC> (consonant + split dependent vowel) >>> >>> <U+0DDC> = <U+0DD9><U+0DCF> >> >> Ok, that explains. What Uniscribe does for Sinhala follows the Khmer spec, >> not the Indic spec (which I agree is unfortunate), so, instead of decomposing >> split matras according to Unicode, it adds the left part, then uses the >> original code for the rest (right) part of the matra. >> >> What it means that it does: >> >> <U+0DDC> = <U+0DD9><U+0DDC> >> >> Now, if the font has correct positioning for U+0DCF, doing the Unicode way >> should be enough. >> >> The new shaper follows Uniscribe here. You can disable that by removing a >> few lines from hb-unicode.cc. Just search for DDC. That would make the new >> shaper match HarfBuzz-old. Though, I consider the fonts broken if they don't >> work with Uniscribe. >> >> So, in this particular case, it may make sense to limit the Uniscribe >> behavior >> to the uniscribe-bug-compatibilty mode. Jonathan, what do you think? > > I have been considering this conundrum and here are my thoughts: > > 1) Ideally any Unicode Sinhala font that 'works' with Uniscribe should > just 'work' on GNU/Linux.
Correct. That will be the case with new HarfBuzz Indic shaper. > 2) I tested a few freely (cost) available fonts that used to be or are > now reference fonts. Two of these work correctly with both the *new* and > *old* shapers. It's definitely possible to develop a font that works with both. > 3) Taking (2) into account, it may be possible for existing GNU/Linux > fonts to support both the new and old shaper. However, I would have to > defer that to someone who knows their way around fonts better. When you find someone who wants to fix the font, let me know and I can tell them exactly what to do. > 4) The way Uniscribe has implemented this is a bit unexpected, what > happens if Uniscribe changes/fixes this? Do we just blindly follow > Uniscribe? In absence of any standard, yes. That said, Microsoft has never changed those kinds of things in a way that would break things. behdad > As you can see, I am undecided on what might be the best direction. > > cya, > # _______________________________________________ HarfBuzz mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/harfbuzz
