digitgrouper

This is a do-over of my hacking around with numderline, using fontforge's built-in rule generation rather than trying to work via a feature file, which causes fontforge to crash. It also uses GPOS rules rather than building new glyphs at different positions and switching them in via GSUB (though new glyphs would be required for the shrink feature anyway -- just not as many).

There's some additional verbiage about this effort over here, for whatever that's worth.

Usage

digitgrouper.py [-h] [--monospace] [--terminal] [--final-rules]
                [--gap-size GAP_SIZE] [--shrink_x SHRINK_X]
                [--shrink_y SHRINK_Y] [--separate-files]
                font [font ...]

--monospace : When inserting the digit-grouping separators, keep the same spacing as the number would have had without those insertions. This is necessary to maintain the expected layout in monospaced type. Digits are pinched together slightly to make extra room where needed. : This may look a bit rough, and might need some extra tinkering with other settings to get it to look right and to work well with some softare.

--terminal : Don't try to emit GPOS rules. Make a whole bunch of extra glyphs at different positions instead. This is only meaningful in --monospace situations, but is necessary when the font will be used by something which caches rendered glyphs without regard to the contextual GPOS edits.

--final-rules : By default the new font rules are inserted before pre-existing rules. Some of the changes this causes might interfere with those existing rules (stylistic sets, etc.). With this switch try putting them at the end, instead. This can cause a permutation explosion of glyph modifications to account for the substitutions that might have happened, but it's more likely to work properly.

--always-on : By default grouping needs to be enabled via font features like dgsp. This enables it under the calt feature, which is default-on.

--gap-size=GAP_SIZE : Fiddle with the size of the separator. By default it tries to duplicate the width of a thin space, or a comma, or a third of the width of a zero. Whatever it finds first. The units vary by font file, so just fiddle with it until it looks right.