Size improvement of font files

[HLammers]

Hi @easytarget,

Thank you for your awesome work! I’m using a highly adjusted version of your code in a project of mine (not yet published) and I’d like to share how I imporved the size of the font file when loaded to memory:

• I changed the dict into a tuple and I changed the get_ch(ch) function accordingly
• I replace the functions in the beginning with constants (some of them don’t seem to be needed, so I commented them out and min_ch and max_ch seem to be only relevant for the get_ch(ch), so I made those local constants (_MIN_CH, _MAX_CH). Of course I needed to adjust the code in exFBfont.py to refer to constants instead of functions.

This is an example:

'''
    ezFBfont_6x10_ascii_10 : generated as part of the microPyEZfonts repository
      https://github.com/easytarget/microPyEZfonts

    This font definition can be used with the "ezFBfont" class provided there.
    It can also be used with the "writer" class from Peter Hinches micropython
      font-to-py tool: https://github.com/peterhinch/micropython-font-to-py

    Original 6x10.bdf font file was sourced from the U8G2 project:
      https://github.com/olikraus/u8g2

'''
# Code generated by bdf2dict.py
# Font: 6x10
# Cmd: ['bdf2dict.py'], ['Latin-1-bdf-sources/6x10.bdf', '_', './ascii-char.set']
# Date: 2024-07-31 14:56:40
'''
    Original Copyright, Comments and Notices from source:

    COMMENT "Public domain terminal emulator font.  Share and enjoy."
'''
version = '0.33'
name = '-misc-fixed-medium-r-normal--10-100-75-75-c-60-iso10646-1'
family = 'fixed'
weight = 'medium'
size = 10

HEIGHT = const(10)
BASELINE = const(8)
MAX_WIDTH = const(6)
# HMAP = const(True)
# REVERSE = const(False)
MONOSPACED = const(True)
_MIN_CH = const(32)
_MAX_CH = const(126)

_g = (
  b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
  b'\x00     \x00 \x00\x00',
  b'\x00PPP\x00\x00\x00\x00\x00\x00',
  b'\x00PP\xf8P\xf8PP\x00\x00',
  b'\x00 p\xa0p(p \x00\x00',
  b'\x00H\xa8P P\xa8\x90\x00\x00',
  b'\x00@\xa0\xa0@\xa8\x90h\x00\x00',
  b'\x00   \x00\x00\x00\x00\x00\x00',
  b'\x00\x10 @@@ \x10\x00\x00',
  b'\x00@ \x10\x10\x10 @\x00\x00',
  b'\x00\x00\x88P\xf8P\x88\x00\x00\x00',
  b'\x00\x00  \xf8  \x00\x00\x00',
  b'\x00\x00\x00\x00\x00\x000 @\x00',
  b'\x00\x00\x00\x00\xf8\x00\x00\x00\x00\x00',
  b'\x00\x00\x00\x00\x00\x00 p \x00',
  b'\x00\x08\x08\x10 @\x80\x80\x00\x00',
  b'\x00 P\x88\x88\x88P \x00\x00',
  b'\x00 `\xa0   \xf8\x00\x00',
  b'\x00p\x88\x080@\x80\xf8\x00\x00',
  b'\x00\xf8\x08\x100\x08\x88p\x00\x00',
  b'\x00\x100P\x90\xf8\x10\x10\x00\x00',
  b'\x00\xf8\x80\xb0\xc8\x08\x88p\x00\x00',
  b'\x000@\x80\xb0\xc8\x88p\x00\x00',
  b'\x00\xf8\x08\x10\x10 @@\x00\x00',
  b'\x00p\x88\x88p\x88\x88p\x00\x00',
  b'\x00p\x88\x98h\x08\x10`\x00\x00',
  b'\x00\x00 p \x00 p \x00',
  b'\x00\x00 p \x000 @\x00',
  b'\x00\x08\x10 @ \x10\x08\x00\x00',
  b'\x00\x00\x00\xf8\x00\xf8\x00\x00\x00\x00',
  b'\x00@ \x10\x08\x10 @\x00\x00',
  b'\x00p\x88\x10  \x00 \x00\x00',
  b'\x00p\x88\x98\xa8\xb0\x80p\x00\x00',
  b'\x00 P\x88\x88\xf8\x88\x88\x00\x00',
  b'\x00\xf0HHpHH\xf0\x00\x00',
  b'\x00p\x88\x80\x80\x80\x88p\x00\x00',
  b'\x00\xf0HHHHH\xf0\x00\x00',
  b'\x00\xf8\x80\x80\xf0\x80\x80\xf8\x00\x00',
  b'\x00\xf8\x80\x80\xf0\x80\x80\x80\x00\x00',
  b'\x00p\x88\x80\x80\x98\x88p\x00\x00',
  b'\x00\x88\x88\x88\xf8\x88\x88\x88\x00\x00',
  b'\x00p     p\x00\x00',
  b'\x008\x10\x10\x10\x10\x90`\x00\x00',
  b'\x00\x88\x90\xa0\xc0\xa0\x90\x88\x00\x00',
  b'\x00\x80\x80\x80\x80\x80\x80\xf8\x00\x00',
  b'\x00\x88\x88\xd8\xa8\x88\x88\x88\x00\x00',
  b'\x00\x88\x88\xc8\xa8\x98\x88\x88\x00\x00',
  b'\x00p\x88\x88\x88\x88\x88p\x00\x00',
  b'\x00\xf0\x88\x88\xf0\x80\x80\x80\x00\x00',
  b'\x00p\x88\x88\x88\x88\xa8p\x08\x00',
  b'\x00\xf0\x88\x88\xf0\xa0\x90\x88\x00\x00',
  b'\x00p\x88\x80p\x08\x88p\x00\x00',
  b'\x00\xf8      \x00\x00',
  b'\x00\x88\x88\x88\x88\x88\x88p\x00\x00',
  b'\x00\x88\x88\x88PPP \x00\x00',
  b'\x00\x88\x88\x88\xa8\xa8\xd8\x88\x00\x00',
  b'\x00\x88\x88P P\x88\x88\x00\x00',
  b'\x00\x88\x88P    \x00\x00',
  b'\x00\xf8\x08\x10 @\x80\xf8\x00\x00',
  b'\x00p@@@@@p\x00\x00',
  b'\x00\x80\x80@ \x10\x08\x08\x00\x00',
  b'\x00p\x10\x10\x10\x10\x10p\x00\x00',
  b'\x00 P\x88\x00\x00\x00\x00\x00\x00',
  b'\x00\x00\x00\x00\x00\x00\x00\x00\xf8\x00',
  b' \x10\x00\x00\x00\x00\x00\x00\x00\x00',
  b'\x00\x00\x00p\x08x\x88x\x00\x00',
  b'\x00\x80\x80\xb0\xc8\x88\xc8\xb0\x00\x00',
  b'\x00\x00\x00p\x88\x80\x88p\x00\x00',
  b'\x00\x08\x08h\x98\x88\x98h\x00\x00',
  b'\x00\x00\x00p\x88\xf8\x80p\x00\x00',
  b'\x000H@\xf0@@@\x00\x00',
  b'\x00\x00\x00x\x88\x88x\x08\x88p',
  b'\x00\x80\x80\xb0\xc8\x88\x88\x88\x00\x00',
  b'\x00 \x00`   p\x00\x00',
  b'\x00\x08\x00\x18\x08\x08\x08HH0',
  b'\x00\x80\x80\x88\x90\xe0\x90\x88\x00\x00',
  b'\x00`     p\x00\x00',
  b'\x00\x00\x00\xd0\xa8\xa8\xa8\x88\x00\x00',
  b'\x00\x00\x00\xb0\xc8\x88\x88\x88\x00\x00',
  b'\x00\x00\x00p\x88\x88\x88p\x00\x00',
  b'\x00\x00\x00\xb0\xc8\x88\xc8\xb0\x80\x80',
  b'\x00\x00\x00h\x98\x88\x98h\x08\x08',
  b'\x00\x00\x00\xb0\xc8\x80\x80\x80\x00\x00',
  b'\x00\x00\x00p\x80p\x08\xf0\x00\x00',
  b'\x00@@\xf0@@H0\x00\x00',
  b'\x00\x00\x00\x88\x88\x88\x98h\x00\x00',
  b'\x00\x00\x00\x88\x88PP \x00\x00',
  b'\x00\x00\x00\x88\x88\xa8\xa8P\x00\x00',
  b'\x00\x00\x00\x88P P\x88\x00\x00',
  b'\x00\x00\x00\x88\x88\x98h\x08\x88p',
  b'\x00\x00\x00\xf8\x10 @\xf8\x00\x00',
  b'\x00\x18 \x10`\x10 \x18\x00\x00',
  b'\x00       \x00\x00',
  b'\x00`\x10 \x18 \x10`\x00\x00',
  b'\x00H\xa8\x90\x00\x00\x00\x00\x00\x00',
)

def get_ch(ch):
    c = ord(ch)
    if _MIN_CH <= c <= _MAX_CH:
        return memoryview(_g[c - _MIN_CH]), HEIGHT, MAX_WIDTH
    return None, 0, 0

[easytarget]

That's cool, playing round with font encodings can be fun, and educational. I hope your project brings joy! etc ;-)

Eliminating the dict structure and all 'extras' will certainly help for a dedicated project! Have you tried the memory tests I used here?

I'd be curious to see the results. I'm wondering why you didnt wrap the whole tuple as a const, which should keep it entirely off the heap. Maybe not needed?

For the fonts I'm publishing I need to keep backwards compatibility with the original format, so externals like REVERSE are needed. For instance min and max ch are used in my glyph dumper. They add very little extra to memory use. It's the dict{} that eats RAM ;-)

The other thing I note is that you are assuming a linear block of characters; this is true in many use cases, but not all. By using a dict I can encode just the characters needed, even when they are spread out in the charset. This was why I chose a dict{} over a simple list[] or tuple() and a index offset.

[peterhinch]

@HLammers The functions are provided to be consistent with fonts produced by font-to-py and compatibility with nano-gui and micro-gu. They use minimal RAM.