ndg/doc/fonts.md

the trouble is fontawesome now supplies multiple files, fa-brands-400.woff2, fa-regular-400.woff2 and fa-solid-900.woff2. don't know which symbol is in which file.

list all defined symbols into a file:

grep 0x ../ngui/lib/lvgl/src/font/lv_symbol_def.h | grep -v 0x2022 | \
  cut -d, -f2 | cut -c4-7 | tr 'A-F' 'a-f' \
  > /tmp/sym.txt

download and unzip fontawesome. expect to find metadata/icons.yml file. grep metadata to find out which set each icon is in:

for c in $(cat /tmp/sym.txt); do
  t=$(grep -B3 "unicode: $c" metadata/icons.yml | grep -- '- ' | head -n1 | tr -d ' -')
  echo "$c\t$t"
done

some icons are in multiple styles. search for the code on https://fontawesome.com/icons/ and compare to the image on https://docs.lvgl.io/8.3/overview/font.html. the command above takes the first one listed in icons.yml, which is usually "solid". when searching on fontawesome, make sure it's a free icon, as opposed to their pro version.

not all icons might be present. at the time of writing, the following codes are amiss:

• 0xf067 LV_SYMBOL_PLUS; actually exists but listed as unicode:2b in icons.yml
• 0xf8a2 LV_SYMBOL_NEW_LINE; looks like fontawesome removed level-down-alt from v6 so i picked an alternative 0xf177 arrow-left-long

dump previous command output into an fa-icon-style.txt file. add missing "solid" style in the second column and replace f8a2 with f177=>0xf8a2 mapping. the latter is the syntax for when running lvgl font convertion tool.

while there, add more codes to the file, separating columns with a single tab:

• 0xf379 brands (bitcoin)
• 0xe0b4 solid (bitcoin-sign)
• 0xf0e7 solid (lightning bolt)

split the previously generated fa-icon-style.txt file into chunks suitable for constructing lvgl's font converter arguments.

first, check which styles are present. at the moment, only "brands" and "solid" are used:

$ cut -f2 fa-icon-style.txt | sort | uniq -c
      3 brands
     61 solid

then split the file, for each style from the previous command. example for "solid":

grep solid fa-icon-style.txt | cut -f1 | tr 'a-f' 'A-F' | \
  while IFS= read -r line; do printf "0x$line\n"; done | \
  paste -s -d, | tr -d '\n' > fa-solid.txt

typically, you'll want to bundle the symbols from fontawesome with a regular font. i'll use courier prime code as an example.

install the font converter tool; requires nodejs:

npm i lvgl/lv_font_conv

finally, convert and bundle all fonts, for 14px size as an example:

./node_modules/.bin/lv_font_conv --no-compress --no-prefilter --bpp 4 --size 14 \
  --font courier-prime-code.ttf -r 0x20-0x7F,0xB0,0x2022 \
  --font fa-brands-400.ttf -r $(cat fa-brands.txt) \
  --font fa-solid-900.ttf -r $(cat fa-solid.txt) \
  --format lvgl --force-fast-kern-format \
  -o lv_font_courierprimecode_14.c 

the arguments are similar to those in the header of any LVGL font in lib/lvgl/src/font/lv_font/xxx.c.