Font Forum

Dear all
I am trying to include a new character into Traditional Arabic font's table. The character is Jawi letter namely as Ghaa' (Arabic leter Ain with 3 dots above: 06A0). It works as Arabic letter Ain (0639, FEC9, FECA, FECB & FECC), except this new letter has three dot above; in other words this new letter has also 4 shapes (same as letter Ain), i.e. when isolated, final, initial & medial forms/ shapes. I tried many times, but the best is it only can appear correctly when it is isolated, the rest goes wrong.
So how could I solve the problem?
God rewards you all.

This is one of those times when you need to be able to access the OpenType features of the font. Specifically, you need to be able to perform a substitution where Ghaa.iso -> Ghaa.init, Ghaa.iso->Ghaa.medi, and Ghaa.iso->Ghaa.fina are each bound to the OpenType features <init>, <medi>, and <fina> in the Arabic script, default (or whatever) language. Without the OpenType substitutions, the main form is the only one that will be displayed. Remember that all of the positional forms up in U+FExx are not used by modern rendering systems. They are only in Unicode for backwards compatibility with older character sets.

Ok Van, does this mean that I have to use another table, i.e. I cannot use the table designed specifically for the Traditional Arabic?
By the way, I think it also related to the specific group characters, i.e. if I could change or add some some characters in the portion for Arabic charactersit might work. Ok, is there a guide in the User Manual of FontCreator or else where that I can refer more about what you have proposed to me- I am quite dont clear about it. Tq very much, God rewards you.

I know that Microsoft typography has some information on using VOLT to add all the right OpenType tables for different scripts, and that their Arabic info is probably the most extensive. I've never made an Arabic font, so I only know what I've been told, but getting proper contextual forms to select is all about binding a substitution table to the features <init>, <medi>, and <fina>. The big task is to make substitution tables that map all of your regular isolate code points to their initial, medial, and final forms. Uniscribe theoretically knows the rules of when to call for positional forms, but I don't think it will work completely properly with characters that are not explicitly known to Uniscribe. That's the problem with the hegemon - it's sometimes hard to customize to your needs.