gff/gff

#!/usr/bin/env python3
from math import ceil
from sys import argv
from PIL import Image, ImageDraw, ImageFont

if (len(argv) < 4):
    raise BaseException("At least three arguments expected: " + \
        "<font path> <font size> <output image> " + \
        "[initial char index] [char range]")

font_path = argv[1]
font_size = int(argv[2])
image_out = argv[3]
initial_char_index = int(argv[4]) if len(argv) > 4 else 0x20
char_range = int(argv[5]) if len(argv) > 5 else 96
line_count = ceil(char_range / 16)
scan_index = 0x20 if len(argv) > 4 else initial_char_index
scan_range = 0x30ff - 0x20 if len(argv) > 4 else char_range

assert char_range > 1

mode = '1' # 1-bit depth
background_color = (1) # white
foreground_color = (0) # black

# load font
font = ImageFont.truetype(font_path, font_size)

# find max char size
char_width = 0
char_height = 0
for i in range(scan_range):
    bbox = list(font.getbbox(chr(scan_index + i)))
    # don't you dare overlap
    if (bbox[0] < 0):
        bbox[2] = -bbox[0]
    if (bbox[1] < 0):
        bbox[3] -= bbox[1]
    if bbox[2] > char_width:
        char_width = bbox[2]
    if bbox[3] > char_height:
        char_height = bbox[3]

image_out_width = char_width * 16
image_out_height = char_height * line_count

# fxconv metadata
print(f"{image_out.split('/')[-1]}:")
print("  type: font")
print("  charset: print")
print(f"  grid.size: {char_width}x{char_height}")

# create image
im = Image.new(mode, (image_out_width, image_out_height))

# draw
draw = ImageDraw.Draw(im)
draw.rectangle((0, 0, image_out_width, image_out_height), fill=background_color)

x = -char_width
y = 0
for i in range(char_range):
    x += char_width
    char = chr(initial_char_index + i)
    bbox = font.getbbox(char)
    x_mod = 0
    y_mod = 0
    # don't you dare overlap
    if (bbox[0] < 0):
        x_mod = -bbox[0]
    if (bbox[1] < 0):
        y_mod = -bbox[1]
    if i != 0 and i % 16 == 0:
        x = 0
        y += char_height
    draw.text((x + x_mod, y + y_mod), char, fill=foreground_color, font=font)

# save
im.save(image_out)