- From: Tab Atkins Jr. <jackalmage@gmail.com>
- Date: Fri, 15 Aug 2014 11:37:38 -0700
- To: Glenn Adams <glenn@skynav.com>
- Cc: John Daggett <jdaggett@mozilla.com>, fantasai <fantasai.lists@inkedblade.net>, WWW International <www-international@w3.org>, www-style list <www-style@w3.org>
On Fri, Aug 15, 2014 at 11:04 AM, Glenn Adams <glenn@skynav.com> wrote: > On Fri, Aug 15, 2014 at 11:34 AM, Tab Atkins Jr. <jackalmage@gmail.com> > wrote: >> On Fri, Aug 15, 2014 at 10:26 AM, Glenn Adams <glenn@skynav.com> wrote: >> > On Fri, Aug 15, 2014 at 11:09 AM, Tab Atkins Jr. <jackalmage@gmail.com> >> > wrote: >> >> You're right about full shaping across a word (thus the note about >> >> "shaping might not result in the glyphs joining correctly"), but >> >> per-character shaping (selecting the initial/medial/final/isolated >> >> form) is necessary for remotely correct rendering, and can happen >> >> regardless of what changes occur from one character to the next. >> > >> > Not necessarily. This could be made to work with, e.g., Arabic script in >> > combination with OpenType GSUB features 'isol', 'init', 'medi', 'fina', >> > but >> > this is only because OT Arabic script support requires the application >> > (in >> > this case the shaper code) to be able to independently determine which >> > form >> > applies and then use the related feature to map to glyph. However, this >> > situation does not necessarily hold for more advanced OT Arabic fonts >> > that >> > use different feature sets, for other complex scripts used with OT, or >> > for >> > TT fonts that use 'mort' table. >> >> Apologies, but you're speaking over my head. Can you dumb it down a >> little so I can understand what you just wrote? > > Ha, that's a change. It's usually the other way around. :) > > Basically I'm saying that "remotely correct rendering" of contextual forms > is highly dependent on script (e.g., Arabic vs Devanagari), on font type (OT > vs TT), on specific font tables use by fonts (on either side of style > boundary) (e.g., OT GSUB with {isol,init,medi,fina} features vs OT GSUB with > non-standard/cutom shaping features vs TT 'mort'). > > Or to put it more simply, what John said: > > "Any property that affects the set of features applied to a given text run > is an input to shaping, so changes in those may affect shaping results." > "[C]omplexities of text handling at this level make it very difficult to > come up with easy generalizations like this [fantasai: shaping is not broken > across an inline element boundary unless ...]." Okay, cool. Based on the little I know, though, you don't need all that complexity just to recognize what basic form the letter will take. The word won't look *good* if the letters are in the right form but not shaped correctly, but it'll be readable at least. It *won't* be readable (or at least will be much harder to read) if the letters are *also* in the wrong form, in addition to not shaping correctly. ~TJ
Received on Friday, 15 August 2014 18:38:28 UTC