On Wed, Nov 30, 2011 at 09:47:31PM +0100, Keith J. Schultz wrote: > Hi Khaled, > > I am afraid you are completely misconceived about what the subject matter is > here. > 1) adding a diacritic mark(glyph) is composing a a glyph, You are able > to output it > on its own. > > 2) There is a difference between the glyph ä and adding the diactirc > mark of umlaut to > an a. > a) in the first case you can use two different colors because it > is one glyph. > b) in the second you can use two different colors because you > two glyph in order > two compose the ä glyph. > > So we are talking about composed glyphs whether you realize it or not.
No we are not: 1) adding a mark to a glyphs is one thing, and composing them into a single glyph is another thing (in Latin fonts the later is a common result of the former, but that is mere implementation detail). The fully vowelled Arabic word مُحَمَّدٌ have a mark (or even two) in each character but no font will compose each <base><mark> into a single glyph (not a font build by a sane person). The same is even true for versatile Latin fonts that allow proper positioning of arbitrary <base><mark> combinations (e.g. many fonts from SIL). 2) the OP is developing his own font, which is neither covering Latin glyphs nor using precomposed glyphs. Regards, Khaled > > regards > Keith. > > > Am 30.11.2011 um 13:56 schrieb Khaled Hosny: > > > On Wed, Nov 30, 2011 at 11:10:11AM +0100, Keith J. Schultz wrote: > >> Hi All, > >> > >> I jump back in. I will cite anybody because what has been said is correct. > >> > >> But, > >> > >> 1) trying to compare a browser, XeTex engine and LuaTeX will not help > >> as they have different methods of composing their output. > >> That is how they compose and position their glyphs. > > > > As far as OpenType processing is concerned they all should give the same > > result, else there is a bug somewhere. > > > >> 2) Most important a composed Unicode glyph is supposed to be just one > >> color!! > > > > No one talked about composed glyphs (certainly not the OP), it was just > > a marginal and unrelated issue to the problem being discussed; coloring > > combining marks without breaking OpenType mark positioning. > > > >> 3) Once you start using color a Unicode composed glyph you no longer > >> are positioning > >> a single composed glyph, but two or more glyphs. > > > > So? Again, coloring components of composed glyphs is not what is being > > discussed here. > > > >> 3.a) color designed in TeX at.al is designed be applied to a box and > >> not glyphs!! > > > > I've hard time understanding what this mean or how the difference, if > > any, is material. AFAIK, TeX knows nothing about color, it handled just > > like any other driver special which TeX makes no effort to interpret not > > to mention "applying" it. > > > >> The question remains how to position the composed glyphs and where and how > >> the color attribute > >> is added to the output. > >> > >> There are therefore two solutions: > >> 1) The Tex way: > >> create a macro to compose the glyph and do the positioning and > >> coloring. > >> > >> 2) The developer way: > >> change the engine so that it firsts generates the composed > >> glyph and then goes back > >> and then applies color to the different glyphs. > > > > 3) The post-2000s way; use/build an OpenType font with proper combining > > mark positioning and apply the colors to individual glyphs à la what > > FireFox/LuaTeX and may be many other does. > > > > Regards, > > Khaled > > > > > > -------------------------------------------------- > > Subscriptions, Archive, and List information, etc.: > > http://tug.org/mailman/listinfo/xetex > > > > > -------------------------------------------------- > Subscriptions, Archive, and List information, etc.: > http://tug.org/mailman/listinfo/xetex -------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex
