#!/usr/bin/env python3

# This is a simple script that prints out the layers in a GIMP XCF file.

# Started from

# https://www.gimp-forum.net/Thread-List-layers-without-loading-image?pid=21911#pid21911

# then expanded after looking at the GIMP XCF code:

# https://gitlab.gnome.org/GNOME/gimp/-/blob/gimp-2-10/app/xcf/xcf-load.c#L1147

# https://gitlab.gnome.org/GNOME/gimp/-/blob/gimp-2-10/app/xcf/xcf-private.h

# which you'll need if you want to expand this beyond just layer names

# and visibility.

# The XCF spec is at

# https://gitlab.gnome.org/GNOME/gimp/-/blob/gimp-2-10/devel-docs/xcf.txt

#

# This is a simple demo that only works with some XCF versions.

import sys

# The layer property types needed to show visibility and which layer is active:

PROP_END = 0

PROP_ACTIVE_LAYER = 2

PROP_VISIBLE = 8

def probe_xcf(filename):

# open the file in readonly binary mode

with open(filename, 'rb') as f:

print("\n===", filename)

# go to the 30th byte

f.seek(30, 0)

# read image properties

while True:

prop_type = int.from_bytes(f.read(4), "big")

prop_size = int.from_bytes(f.read(4), "big")

f.read(prop_size)

if prop_type == PROP_END:

break

# read layers

while True:

next_layer_offset = int.from_bytes(f.read(8), "big")

if not next_layer_offset: # end of layers offsets

break;

saved_pos = f.tell()

f.seek(next_layer_offset + 12, 0)

namelen = int.from_bytes(f.read(4), "big")

# namelen may include a null terminating character,

# (see line L226 of the XCF spec)

# which Python doesn't use, so strip it off:

name = f.read(namelen).decode("utf-8").replace('\0', '')

print('\nLayer "%s"' % name, end='')

while True:

prop_type = int.from_bytes(f.read(4), "big")

prop_size = int(int.from_bytes(f.read(4), "big") / 4)

# print(prop_type, "size", prop_size)

# The size says how many additional bytes need to be read.

# Read them now, saving only the last one.

for i in range(prop_size):

lastint = int.from_bytes(f.read(4), "big")

if prop_type == PROP_VISIBLE:

if lastint:

print(" Visible", end='')

else:

print(" Invisible", end='')

break

elif prop_type == PROP_ACTIVE_LAYER:

print(" Active", end='')

f.seek(saved_pos, 0)

print()

if __name__ == "__main__":

for f in sys.argv[1:]:

probe_xcf(f)