Parse PCF tables

pcfdump.py

#!/usr/bin/env python3

from struct import unpack
from argparse import ArgumentParser, FileType

# Info taken from https://fontforge.org/docs/techref/pcf-format.html

PCF_PROPERTIES       = (1<<0)
PCF_ACCELERATORS     = (1<<1)
PCF_METRICS          = (1<<2)
PCF_BITMAPS          = (1<<3)
PCF_INK_METRICS      = (1<<4)
PCF_BDF_ENCODINGS    = (1<<5)
PCF_SWIDTHS          = (1<<6)
PCF_GLYPH_NAMES      = (1<<7)
PCF_BDF_ACCELERATORS = (1<<8)

PCF_TYPE_MAP = {
    PCF_PROPERTIES: 'PROPERTIES',
    PCF_ACCELERATORS: 'ACCELERATORS',
    PCF_METRICS: 'METRICS',
    PCF_BITMAPS: 'BITMAPS',
    PCF_INK_METRICS: 'INK_METRICS',
    PCF_BDF_ENCODINGS: 'BDF_ENCODINGS',
    PCF_SWIDTHS: 'SWIDTHS',
    PCF_GLYPH_NAMES: 'GLYPH_NAMES',
    PCF_BDF_ACCELERATORS: 'BDF_ACCELERATORS'
}

PCF_DEFAULT_FORMAT     = 0x00000000
PCF_INKBOUNDS          = 0x00000200
PCF_ACCEL_W_INKBOUNDS  = 0x00000100
PCF_COMPRESSED_METRICS = 0x00000100

PCF_FORMAT_MAP = {
    PCF_DEFAULT_FORMAT: 'DEFAULT_FORMAT',
    PCF_INKBOUNDS: 'INKBOUNDS',
    PCF_ACCEL_W_INKBOUNDS: 'ACCEL_W_INKBOUNDS',
    PCF_COMPRESSED_METRICS: 'COMPRESSED_METRICS'
}

PCF_GLYPH_PAD_MASK = (3<<0)  # See the bitmap table for explanation
PCF_BYTE_MASK      = (1<<2)  # If set then Most Sig Byte First
PCF_BIT_MASK       = (1<<3)  # If set then Most Sig Bit First
PCF_SCAN_UNIT_MASK = (3<<4)  # See the bitmap table for explanation

PCF_FORMAT_MODIFIERS_MAP = {
    PCF_GLYPH_PAD_MASK: 'GLYPH_PAD',
    PCF_BYTE_MASK: 'BYTE',
    PCF_BIT_MASK: 'BIT',
    PCF_SCAN_UNIT_MASK: 'SCAN_UNIT'
}

def pcf_format_str(f):
    f_str = PCF_FORMAT_MAP.get(f & ~0xff, 'Unknown format')
    # really fancy code to iterate all of the flags and select the strings
    # coresponding to the ones that are set
    f_mod_str = ', '.join([v for k, v in iter(PCF_FORMAT_MODIFIERS_MAP.items()) if k & (f & 0xff)])
    return f'{f_str} ({f_mod_str if f_mod_str != "" else "None"})'

def main():

    ap = ArgumentParser(description='View information about a PCF file')
    ap.add_argument('infile', type=FileType('rb'), help='The file to process')

    args = ap.parse_args()

    magic, table_count = unpack('<4sI', args.infile.read(8))

    if magic != b'\x01fcp':
        print(f'Error: bad magic: {magic}')
        args.infile.close()
        return 1

    for _ in range(table_count):
        t_type, t_format, t_size, t_offset = unpack('<4I', args.infile.read(16))
        print(f"""{PCF_TYPE_MAP.get(t_type, 'Unknown type')}, {pcf_format_str(t_format)}
  size: {t_size:08x}, offset: {t_offset:08x}""")

    args.infile.close()
    return 0

if __name__ == '__main__':
    exit(main())