You might have better luck with your question if you join the FontForge List at sourceforge.net. There is a User List there and the FontForge developers read it as well.

Here is a suggestion that may work, if you want to keep all tables intact: try ttx. It comes with AFDKO, the Adobe Font Development Kit for OpenType (which provides other tools to manipulate font tables).

Once ttx is installed, I suggest you decompile only the glyf and the name table with the line command:

   ttx -t name -t glyf CharisSIL-R.ttf

This creates the file CharisSIL-R.ttx (if you repeat, a version number is added to the name).

If you already designed your modified glyph, you apply ttx -t glyf on that font; for example, if the glyph you modified is ccedilla, then replace the text in CharisSIL-R.ttx between

<TTGlyph name="ccedilla" xMin="66" yMin="-457" xMax="825" yMax="1012">

and the closing

</TTGlyph>

with the new description of ccedilla figuring in the ttx file of your new set of glyphs. You also change the font names according to your needs (and the EULA) in the name table.

You finally apply

   ttx -m CharisSIL-R.ttf CharisSIL-R.ttx

to obtain your new font file CharisSIL-R#1.ttf which is likely to work better than the font you generated with fontforge.

I used a variation of that method with AAT fonts and it saved me many calls to the standard tool to generate AAT fonts. If it works fine for you with Graphite tables, please keep us informed.

Here, I presume you keep the character width intact as well as its position in the bounding box (else you will need to work harder).

Hi Michel,

Now I figured out how to change a glyph's width too: the glyph's "mtx" attribute in the "hmtx" table has to be changed accordingly.

The project in question is "Phonetically Intuitive English" (https://sites.google.com/site/phoneticallyintuitiveenglish/). I will mention you in its Acknowledgments :-)

Regards,
Ziyuan Yao

I think this thread should be moved from "general discussion" to the build forum

I just checked with Charis in the present context, with ttx and fontforge, and the reordering does not seem necessary. The other tools I was using required it. That is something I experimented about 18 months ago (during my summer vacations) and that was left undocumented.