Improving Kannada Fonts

Pravin, maintainer of Lohit fonts started lohit2_ project to update all lohit fonts according to Open Type specifications. Read more here and here

I am planning to improve Lohit Kannada(also Gubbi and Navilu) and identified following stages.

Stage one

Clone lohit2, Gubbi and Navilu
Rename all base glyphs according to the standard(uniXXXX format)
Adjust left/right spacing for all base glyphs
Testing

Stage two

Create half forms of base glyphs which are required for creating ligatures.
Delete the unused ligatures(Can be achieved using rules)
Add GSUB rules for consonants.
Mark to Base GPOS rules.
Identify special consonant for which separate ligature is required.(ki, gi etc)
Testing

Stage three

Create ligatures which are identified in previous stage.(Most of the ligatures already exists in fonts)
Add GSUB rules for those ligatures
Testing

Stage four

Rename all vattakshara glyphs.
Add GSUB rules.
Mark to Base GPOS rules for vattakshara
Testing

Stage five

Mark to Mark GPOS rules for double vattakshara.
Create additional ligatures if required for any double vattakshara combination.
Testing

Stage six

Verify and add additional glyphs/symbols required.
Adjust left and right spacing for additional glyphs.
Testing

Stage seven

Typography related improvements: Reduce the font thickness, space and kerning improvements.
Update License, Authors, version and other information.
Testing

Today I completed first stage, created two Python scripts to change the glyph names and to adjust left and right space.

cd $WORK
git clone https://github.com/aravindavk/fontscripts.git
git clone https://github.com/aravindavk/lohit2.git
git clone https://github.com/aravindavk/Gubbi.git
git clone https://github.com/aravindavk/Navilu.git
cd fontscripts

# Lohit Kannada
python rename_base_glyphs.py ../lohit2/kannada/Lohit-Kannada.sfd
python adjust_spacing.py ../lohit2/kannada/Lohit-Kannada.sfd

# Gubbi
python rename_base_glyphs.py ../Gubbi/Gubbi.sfd
python adjust_spacing.py ../Gubbi/Gubbi.sfd

# Navilu
python rename_base_glyphs.py ../Navilu/Navilu.sfd
python adjust_spacing.py ../Navilu/Navilu.sfd

Now generate the fonts to test the changes. Harfbuzz can be used for testing.

hb-view ../lohit2/kannada/Lohit-Kannada.ttf "$(cat stage1_tests.txt )" --output-file preview_lohit.png

Let me know if anybody interested to join and contribute to improve Kannada fonts.