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#!/usr/bin/python
# ##### BEGIN GPL LICENSE BLOCK #####
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# ##### END GPL LICENSE BLOCK #####
"""
Thumbnailer runs with python 2.6 and 3.x.
To run automatically with nautilus:
gconftool --type boolean --set /desktop/gnome/thumbnailers/application@x-blender/enable true
gconftool --type string --set /desktop/gnome/thumbnailers/application@x-blender/command "blender-thumbnailer.py %i %o"
"""
import struct
def blend_extract_thumb(path):
import os
# def MAKE_ID(tag): ord(tag[0])<<24 | ord(tag[1])<<16 | ord(tag[2])<<8 | ord(tag[3])
REND = 1145980242 # MAKE_ID(b'REND')
TEST = 1414743380 # MAKE_ID(b'TEST')
blendfile = open(path, 'rb')
head = blendfile.read(12)
if head[0:2] == b'\x1f\x8b': # gzip magic
import gzip
blendfile.close()
blendfile = gzip.open(path, 'rb')
head = blendfile.read(12)
if not head.startswith(b'BLENDER'):
blendfile.close()
return None, 0, 0
is_64_bit = (head[7] == b'-')
# true for PPC, false for X86
is_big_endian = (head[8] == b'V')
# blender pre 2.5 had no thumbs
if head[9:11] <= b'24':
return None, 0, 0
sizeof_bhead = 24 if is_64_bit else 20
int_endian_pair = '>ii' if is_big_endian else '<ii'
while True:
bhead = blendfile.read(sizeof_bhead)
if len(bhead) < sizeof_bhead:
return None, 0, 0
code, length = struct.unpack(int_endian_pair, bhead[0:8]) # 8 == sizeof(int) * 2
if code == REND:
blendfile.seek(length, os.SEEK_CUR)
else:
break
if code != TEST:
return None, 0, 0
try:
x, y = struct.unpack(int_endian_pair, blendfile.read(8)) # 8 == sizeof(int) * 2
except struct.error:
return None, 0, 0
length -= 8 # sizeof(int) * 2
if length != x * y * 4:
return None, 0, 0
image_buffer = blendfile.read(length)
if len(image_buffer) != length:
return None, 0, 0
return image_buffer, x, y
def write_png(buf, width, height):
import zlib
# reverse the vertical line order and add null bytes at the start
width_byte_4 = width * 4
raw_data = b"".join([b'\x00' + buf[span:span + width_byte_4] for span in range((height - 1) * width * 4, -1, - width_byte_4)])
def png_pack(png_tag, data):
chunk_head = png_tag + data
return struct.pack("!I", len(data)) + chunk_head + struct.pack("!I", 0xFFFFFFFF & zlib.crc32(chunk_head))
return b"".join([
b'\x89PNG\r\n\x1a\n',
png_pack(b'IHDR', struct.pack("!2I5B", width, height, 8, 6, 0, 0, 0)),
png_pack(b'IDAT', zlib.compress(raw_data, 9)),
png_pack(b'IEND', b'')])
if __name__ == '__main__':
import sys
if len(sys.argv) < 2:
print("Expected 2 arguments <input.blend> <output.png>")
else:
file_in = sys.argv[-2]
buf, width, height = blend_extract_thumb(file_in)
if buf:
file_out = sys.argv[-1]
f = open(file_out, "wb")
f.write(write_png(buf, width, height))
f.close()
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