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I'd like to make a (Latin, English) bitmap-stle cursive font in FontForge. I want to treat initial, final, medial, and isolated forms of some letters. I cannot figure out how to get this to work. (Ligatures are working fine).

Here is a minimal example of what I tried:

Make a minimal bitmap font for testing
  • Open fontforge and create a new (empty) font.
  • MenuElementBitmap Strikes Available… and proceed through the dialog to generate bitmap strikes.
  • Double click on the slot for n and draw its bitmap.
  • MenuEncodingAdd Encoding Slots…, add 4 slots.
  • Double click each of these new slots in turn to open them, and rename them n.init n.medi n.fina n.isol using MenuElementGlyph Info… and then selecting the Unicode sub-dialog from the list on the left, and entering the name into the Glyph Name: text box at the top of the window.
  • Select n in the chracer map, type ctl+c to copy its bitmap, and type ctl+v to clone this bitmap into the four slots above. Manually edit each of the n.init n.medi n.fina n.isol to be distinctive for debugging purposes (so I can clearly see when they are active).
  • Also draw an (empty) bitmap for the space character (we'll use it in testing).
Define lookups for initial, medial, final, isolated variants
  • MenuElementFont Info… then from the list on the left-hand side of the dialog click Lookups. The GSUB tab should appear on top with some buttons to the right.
  • Add the init Initial forms lookup table.
    • Click Add Lookup on the right hand side, this will open a Lookup dialog.
    • From the Type: dropdown at the top, select Single Substitution.
    • In the Feature column of the table below, select the dropdown next to the <New> text and scroll down to init
    • Confirm that the Script(s) & Language(s) column is populated with latn{dflt} (although I also tried latn{dflt} DFLT{dflt} for good measure, to no avail).
    • Click Ok to finish.
    • Repeat these steps to make lookup tables for the feature types medi fina and isol.
  • In the GSUB tab of the Lookups sub-diaglog, you should now see lists of init/fina/medi/isol types with a [+] to the left.
  • Click on e.g. init and press the Add Subtable from the list of buttons on the right of the dialog. Choose a name like n.init.
    • In the table column Base Glyph Name, click <New> and type the glypn name (in this case n).
    • In the table column Replacement Glyph Name, type n.init.
    • Press Ok to finish.
    • Repeat these steps similarly for the fina, medi, and isol classes.
Test it in the preview window
  • To test, we'll bring up the Print dialog. On my system this menu optoin is grayed out in the main character map window, but if I bring up the metrics window using ctl+k, bring it into focus, I can then type ctl+p to bring this up. We will only use the Display tab from this dialog, ignore the Print tab.
  • Press the radio button bitmap to tell it to use the provided bitmaps for font testing.
  • Type something like `" n nn nnn nnnn n " to check whether the base, initial, final, medial, or isolate glyph variantes are being used.
  • In my case, only the base n is ever used.
  • Notably, the fina/init/isol/medi rules are not selected in the list in the top left. Clicking on them to try to activate them doesn't seem to do anything.

I installed fontforge from the Ubuntu repositories, here is the output of fontforge --version:

Copyright (c) 2000-2022. See AUTHORS for Contributors.
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
 with many parts BSD <http://fontforge.org/license.html>. Please read LICENSE.
 Version: 20201107
 Based on sources from 2022-01-13 19:13 UTC-ML-D-GDK3.
PythonUI_Init()
copyUIMethodsToBaseTable()
fontforge 20201107
build date: 2022-01-13 19:13 UTC

Summary:

I'm trying to define variants for initial/final/medial/isolated for a cursive-esque Latin English bitmap-style font.

Fontforge does not seem to use the defined init/fina/medi/isol rules or the characters bound to them in its Display dialog.

I do not think this is a bug in fontforge's Display dialog because ligatures (steps not shown) render fine here. It appears that the init/fina/medi/isol rules are just not used.

Indeed, if I go back and add arab{dflt} to the Script(s) & Language(s) column of a lookup table, then highlighting the test text in the Display dialog and typing arab{dflt} in the scripts text box above the test area reveals the init/fina/medi/isol forms --- and also changes the text to right-to-left.

So, it seems that the init/fina/medi/isol forms only work in Arabic fonts. Fair enough, but what is the simplest procedure for getting these to be active in a Latin cursive font? I have searched and the tutorials I found so far are mind-bogglingly convoluted.

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