<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'> <BR> <DIV id=SkyDrivePlaceholder></DIV> <DIV>> Date: Wed, 18 Apr 2012 07:16:17 +0100<BR>> From: jfkthame@googlemail.com<BR>> To: harfbuzz@lists.freedesktop.org<BR>> Subject: Re: [HarfBuzz] A problem in thai shaper<BR>> <BR>> On 18/4/12 02:22, Behdad Esfahbod wrote:<BR>> > On 04/17/2012 06:47 PM, Khaled Hosny wrote:<BR>> >> On Tue, Apr 17, 2012 at 05:10:37AM +0200, Khaled Hosny wrote:<BR>> >>> On Mon, Apr 16, 2012 at 09:08:49PM -0400, Behdad Esfahbod wrote:<BR>> >>>>> Problem 2:<BR>> >>>>><BR>> >>>>> When there is no consonant exist, the dotted circle should be inserted as base<BR>> >>>>> character. The logic should be the first step for the shaping engine to find<BR>> >>>>> the invalid combing marks. Refer to<BR>> >>>>> http://www.microsoft.com/typography/otfntdev/thaiot/shaping.aspx#comb<BR>> >>>><BR>> >>>> Right. We do not handle invalid combining marks yet. That's something I want<BR>> >>>> to do at some point but it's not high priority.<BR>> >>><BR>> >>> I don't know about Thai, but the handling of "invalid" Arabic combining<BR>> >>> marks in Uniscribe is completely brain dead and a real PITA and I'd<BR>> >>> really like not to see HarfBuzz going there, a shaping engine is not a<BR>> >>> spell checker and should not enforce any input pattern.<BR>> >>><BR>> >>> http://www.microsoft.com/typography/OpenType%20Dev/arabic/shaping.mspx#invalid<BR>> >><BR>> >> Incidentally, I came across this Typophile post, which is one example of<BR>> >> why this "invalid" mark handling is not really a good idea:<BR>> >> http://typophile.com/node/92130<BR>> ><BR>> > Interesting. I'm undecided about this as of now.<BR>> <BR>> Just adding my vote in favor of Khaled's position.<BR>> <BR>> The shaping engine should not attempt to enforce rules such as "only one <BR>> vowel mark on each consonant" or "nukta cannot apply to vowels" (IIRC, <BR>> MS may have relented on that one) or "the vowel mark must precede the <BR>> tone mark", etc. That's the role of a (language-specific) spell-checker.<BR>> <BR>> JK</DIV> <DIV> </DIV> <DIV>If shaping engine not attempt to enforce rules as your comments, it is necessary to anaylze the syllable of indic, because this belong to (language-spefic), the shaping engine only need apply all the feature that set by user. The user need analyze the syllable and decide to apply which feature should be applied. I don't think that is a good idea. not each of user is doing for a editor<BR>so we can't expect each of user is a language expert. The editor can be used to check the word or other someting, but not the atom element (example the syllable of indic or thai). </DIV> <DIV> </DIV> <DIV>Br,</DIV> <DIV>Dean</DIV> <DIV>> _______________________________________________<BR>> HarfBuzz mailing list<BR>> HarfBuzz@lists.freedesktop.org<BR>> http://lists.freedesktop.org/mailman/listinfo/harfbuzz<BR></DIV> </div></body> </html>