Convert a Bitfontmaker JSON into PNG

bitfont.py

# -*- coding: utf-8 -*-

# Convert a Bitfontmaker JSON into PNG (requires Pillow library)
#
# See gallery:
# http://www.pentacom.jp/pentacom/bitfontmaker2/gallery/
#
# Usage:
# python bitfont.py font.json font.png

import sys
import json
from PIL import Image

# Transparent background
BACKGROUND_COLOR = 1, 1, 1, 1

# In order to WebGL friendly the final spritesheet must be a power of two
SIZE = 256, 512

# Render each glyph at ideal size (px)
GLYPH_WIDTH = 16

# Added some padding -- final size should be
#  a power of two, so everything align nicely
CELL_SIZE = GLYPH_WIDTH

# All ASCII characters we need
CHARACTERS = range(ord(' '), ord('z') + 1)

BITMASKS = [2**v for v in range(16)]

def draw_glyph(img, position, values):

    x, y = position

    for offset_y, value in enumerate(values):
        if value == 0:
            continue # Skip row

        for offset_x, bit in enumerate(BITMASKS):
            if value & bit:
                img.putpixel((x * CELL_SIZE + offset_x, y * CELL_SIZE + offset_y), (0, 0, 0))


def main(args):
    _, input_path, output_path = args[0], args[1], args[2]

    img = Image.new('RGBA', SIZE, color=BACKGROUND_COLOR)

    with open(input_path) as f:
        data = cleanup(json.load(f, encoding="utf-8"))

        for index, value in enumerate(CHARACTERS):
            try:
                glyph = data[str(value)]
            except KeyError:
                continue

            col = index % (SIZE[0] / CELL_SIZE)
            row = index // (SIZE[0] / CELL_SIZE)

            draw_glyph(img, (col, row), glyph)

    img.save(output_path, 'PNG')


unwanted = [
    "name",
    "copy",
    "letterspace",
    "basefont_size",
    "basefont_left",
    "basefont_top",
    "basefont",
    "basefont2"
]

def cleanup(data):

    for key in unwanted:
        del data[key]

    return data

if __name__ == '__main__':
    if len(sys.argv) < 3:
        print "Not enough arguments given."
    else:
        main(sys.argv)