This file is a python script (that requires Pillow/PIL) to decode a ctrulib font file to an image, or encode a png to a ctrulib font file

ctrulib_fonttool.py

"""
This file is a python script (that requires Pillow/PIL) to decode a ctrulib font file to an image, or encode a png to a ctrulib font file
ctrulib: https://github.com/smealum/ctrulib

Copyright (C) 2019 LiquidFenrir

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Additional Terms 7.b and 7.c of GPLv3 apply to this file:
    * Requiring preservation of specified reasonable legal notices or
      author attributions in that material or in the Appropriate Legal
      Notices displayed by works containing it.
    * Prohibiting misrepresentation of the origin of that material,
      or requiring that modified versions of such material be marked in
      reasonable ways as different from the original version.
"""

from PIL import Image
import struct
import argparse

def decode_font_bin(inpath, outpath):
    with open(inpath, "rb") as f:
        data = f.read()
    
    img = Image.new("RGBA", (16*8, 16*8))
    
    x = 16*8 - 8
    y = 0
    for i in range(256):
        rows = struct.unpack_from("8B", data, i*8)
        for py, row in enumerate(rows, y):
            for px in range(8):
                pixel = bool((row >> px) & 1)
                img.putpixel((py, px + x), 0xFFFFFFFF if pixel else 0)
        x -= 8
        if x == -8:
            x = 16*8 - 8
            y += 8

    img.rotate(-90).save(outpath)

def encode_font_bin(inpath, outpath):
    data = [0] * (2048)
    pixels = list(Image.open(inpath).rotate(90).convert("RGBA").getdata(3))
    
    data = [0] * 2048

    x = 0
    y = 16*8 - 1
    for character in range(256):
        for py in range(8):
            num = 0
            for px in range(8):
                if pixels[(y - px)*128 + py + x]:
                    num |= 1 << (8 - px - 1)
            data[character * 8 + py] = num
        y -= 8
        if y < 0:
            x += 8
            y = 16*8 - 1

    with open(outpath, "wb") as f:
        f.write(bytearray(data))
    
if __name__ == "__main__":
    actions_dict = {
        "decode": decode_font_bin,
        "encode": encode_font_bin,
    }
    parser = argparse.ArgumentParser(description="")
    parser.add_argument("to_do", choices=actions_dict.keys(), help="Action to perform")
    parser.add_argument("-i", "--infile", "--in", help="Input file (either a .bin or an image file)")
    parser.add_argument("-o", "--outfile", "--out", help="Output file")

    args = parser.parse_args()
    
    actions_dict[args.to_do](args.infile, args.outfile)