ZPL GRF Extractor

This project contains the utilities to work with GRF images from ZPL (Zebra Programming Languages).

Currently supported commands: ~DG, ^GF

Init project

python3 -m venv ./venv
source venv/bin/activate
pip install --upgrade pip
pip install -r requirements.txt

Examples

Extracting ~DG commands from ZPL code and generating PIL images

from zplgrf import *

input_zpl_file_path = './zpl_dg/example.zpl'

# Read ZPL code from a file
with open(input_zpl_file_path, 'r') as in_file:
    zpl = in_file.read()

# Find and extract ~DG commands
dg_cmds_indexes = find_dg_commands(zpl)
dg_cmds = extract_commands(zpl, dg_cmds_indexes)
for dg_cmd in dg_cmds:
    # Extract parameters from ~DG commands
    device, image_name, extension, bytes_total, bytes_per_row, data = break_dg_command(dg_cmd)
    data = clean(data)
    # Check for compression and decompress if needed
    is_compressed = check_for_compression(data)
    if is_compressed:
        data = decompress(data, bytes_per_row)
    # Generate a PIL image
    data_bits = chars_to_bits(data)
    bits_total = size_byte_to_bit(bytes_total)
    bits_per_row = size_byte_to_bit(bytes_per_row)
    image = bits_to_image(bits_total, bits_per_row, data_bits)
    image.save('./img/dg_cmd_format.png')

Generating ~DG command ZPL code from a PIL image

from zplgrf import *

input_img_file_path = './img/000.png'

# Read image from a file
image = Image.open(input_img_file_path)

# Generate a ~DG command with compressed data from PIL image
bits_total, bits_per_row, data_bits = image_to_bits(image)
bytes_total = size_bit_to_byte(bits_total)
bytes_per_row = size_bit_to_byte(bits_per_row)
data = bits_to_chars(data_bits)
data = compress(data, bytes_per_row)
dg_cmd = build_dg_command(bytes_total, bytes_per_row, data, '000')
# Generate ZPL code with generated ~DG command
zpl = write_zpl(dg_cmd, 20, 20, 1, 1)

output_zpl_file_path = './zpl/example.zpl'
with open(output_zpl_file_path, 'w') as out_file:
    out_file.write(zpl)

Extracting ^GF commands from ZPL code and generating PIL images

from zplgrf import *

input_zpl_file_path = './zpl_gf/example.zpl'

# Read ZPL code from a file
with open(input_zpl_file_path, 'r') as in_file:
    zpl = in_file.read()

# Find and extract ^GF commands
gf_cmds_indexes = find_gf_commands(zpl)
gf_cmds = extract_commands(zpl, gf_cmds_indexes)
for gf_cmd in gf_cmds:
    # Extract parameters from ^GFA commands
    compression_type, binary_byte_count, graphic_field_count, bytes_per_row, data = break_gf_command(gf_cmd)
    data = clean(data)
    # Check for compression and decompress if needed
    is_compressed = check_for_z64_compression(data)
    if is_compressed:
        data = decompress_z64(data)
    # Generate a PIL image
    data_bits = chars_to_bits(data)
    bits_total = size_byte_to_bit(binary_byte_count)
    bits_per_row = size_byte_to_bit(bytes_per_row)
    image = bits_to_image(bits_total, bits_per_row, data_bits)
    image.save('./img/gf_cmd_format.png')

ZPL

Manual for Zebra Programming Language can be found here. This project utilizes ~DG command explained on page 158 and possible compression explained on page 1582.