forked from bartvdbraak/blender
156 lines
4.3 KiB
Python
Executable File
156 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python
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# ##### BEGIN GPL LICENSE BLOCK #####
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version 2
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# of the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software Foundation,
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# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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#
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# ##### END GPL LICENSE BLOCK #####
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# <pep8 compliant>
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"""
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Thumbnailer runs with python 2.6 and 3.x.
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To run automatically with nautilus:
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gconftool --type boolean --set /desktop/gnome/thumbnailers/application@x-blender/enable true
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gconftool --type string --set /desktop/gnome/thumbnailers/application@x-blender/command "blender-thumbnailer.py %u %o"
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"""
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import struct
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def open_wrapper_get():
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""" wrap OS spesific read functionality here, fallback to 'open()'
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"""
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def open_gio(path, mode):
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g_file = gio.File(path).read()
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g_file.orig_seek = g_file.seek
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def new_seek(offset, whence=0):
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return g_file.orig_seek(offset, [1, 0, 2][whence])
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g_file.seek = new_seek
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return g_file
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try:
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import gio
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return open_gio
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except ImportError:
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return open
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def blend_extract_thumb(path):
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import os
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open_wrapper = open_wrapper_get()
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# def MAKE_ID(tag): ord(tag[0])<<24 | ord(tag[1])<<16 | ord(tag[2])<<8 | ord(tag[3])
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REND = 1145980242 # MAKE_ID(b'REND')
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TEST = 1414743380 # MAKE_ID(b'TEST')
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blendfile = open_wrapper(path, 'rb')
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head = blendfile.read(12)
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if head[0:2] == b'\x1f\x8b': # gzip magic
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import gzip
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blendfile.close()
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blendfile = gzip.GzipFile('', 'rb', 0, open_wrapper(path, 'rb'))
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head = blendfile.read(12)
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if not head.startswith(b'BLENDER'):
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blendfile.close()
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return None, 0, 0
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is_64_bit = (head[7] == b'-'[0])
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# true for PPC, false for X86
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is_big_endian = (head[8] == b'V'[0])
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# blender pre 2.5 had no thumbs
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if head[9:11] <= b'24':
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return None, 0, 0
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sizeof_bhead = 24 if is_64_bit else 20
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int_endian_pair = '>ii' if is_big_endian else '<ii'
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while True:
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bhead = blendfile.read(sizeof_bhead)
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if len(bhead) < sizeof_bhead:
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return None, 0, 0
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code, length = struct.unpack(int_endian_pair, bhead[0:8]) # 8 == sizeof(int) * 2
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if code == REND:
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blendfile.seek(length, os.SEEK_CUR)
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else:
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break
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if code != TEST:
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return None, 0, 0
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try:
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x, y = struct.unpack(int_endian_pair, blendfile.read(8)) # 8 == sizeof(int) * 2
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except struct.error:
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return None, 0, 0
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length -= 8 # sizeof(int) * 2
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if length != x * y * 4:
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return None, 0, 0
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image_buffer = blendfile.read(length)
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if len(image_buffer) != length:
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return None, 0, 0
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return image_buffer, x, y
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def write_png(buf, width, height):
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import zlib
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# reverse the vertical line order and add null bytes at the start
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width_byte_4 = width * 4
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raw_data = b"".join(b'\x00' + buf[span:span + width_byte_4] for span in range((height - 1) * width * 4, -1, - width_byte_4))
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def png_pack(png_tag, data):
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chunk_head = png_tag + data
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return struct.pack("!I", len(data)) + chunk_head + struct.pack("!I", 0xFFFFFFFF & zlib.crc32(chunk_head))
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return b"".join([
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b'\x89PNG\r\n\x1a\n',
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png_pack(b'IHDR', struct.pack("!2I5B", width, height, 8, 6, 0, 0, 0)),
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png_pack(b'IDAT', zlib.compress(raw_data, 9)),
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png_pack(b'IEND', b'')])
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if __name__ == '__main__':
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import sys
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if len(sys.argv) < 3:
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print("Expected 2 arguments <input.blend> <output.png>")
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else:
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file_in = sys.argv[-2]
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buf, width, height = blend_extract_thumb(file_in)
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if buf:
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file_out = sys.argv[-1]
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f = open(file_out, "wb")
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f.write(write_png(buf, width, height))
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f.close()
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