/usr/lib/python3/dist-packages/audiotools/image.py is in audiotools 3.1.1-1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Copyright (C) 2007-2015 Brian Langenberger
# 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
from audiotools.bitstream import BitstreamReader, format_size
from audiotools import InvalidImage
def image_metrics(file_data):
"""returns an ImageMetrics subclass from a string of file data
raises InvalidImage if there is an error parsing the file
or its type is unknown"""
if file_data[0:3] == b"\xff\xd8\xff":
return __JPEG__.parse(file_data)
elif file_data[0:8] == b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A':
return __PNG__.parse(file_data)
elif file_data[0:3] == b'GIF':
return __GIF__.parse(file_data)
elif file_data[0:2] == b'BM':
return __BMP__.parse(file_data)
elif (file_data[0:2] == b'II') or (file_data[0:2] == b'MM'):
return __TIFF__.parse(file_data)
else:
from audiotools.text import ERR_IMAGE_UNKNOWN_TYPE
raise InvalidImage(ERR_IMAGE_UNKNOWN_TYPE)
#######################
# JPEG
#######################
class ImageMetrics:
"""a container for image data"""
def __init__(self, width, height, bits_per_pixel, color_count, mime_type):
"""fields are as follows:
width - image width as an integer number of pixels
height - image height as an integer number of pixels
bits_per_pixel - the number of bits per pixel as an integer
color_count - for palette-based images, the total number of colors
mime_type - the image's MIME type, as a unicode string
all of the ImageMetrics subclasses implement these fields
in addition, they all implement a parse() classmethod
used to parse binary string data and return something
imageMetrics compatible
"""
self.width = width
self.height = height
self.bits_per_pixel = bits_per_pixel
self.color_count = color_count
self.mime_type = mime_type
def __repr__(self):
return "ImageMetrics(%s,%s,%s,%s,%s)" % \
(repr(self.width),
repr(self.height),
repr(self.bits_per_pixel),
repr(self.color_count),
repr(self.mime_type))
@classmethod
def parse(cls, file_data):
raise NotImplementedError()
class InvalidJPEG(InvalidImage):
"""raised if a JPEG cannot be parsed correctly"""
pass
class __JPEG__(ImageMetrics):
def __init__(self, width, height, bits_per_pixel):
ImageMetrics.__init__(self, width, height, bits_per_pixel,
0, u'image/jpeg')
@classmethod
def parse(cls, file_data):
def segments(reader):
if reader.read(8) != 0xFF:
from audiotools.text import ERR_IMAGE_INVALID_JPEG_MARKER
raise InvalidJPEG(ERR_IMAGE_INVALID_JPEG_MARKER)
segment_type = reader.read(8)
while segment_type != 0xDA:
if segment_type not in {0xD8, 0xD9}:
yield (segment_type, reader.substream(reader.read(16) - 2))
else:
yield (segment_type, None)
if reader.read(8) != 0xFF:
from audiotools.text import ERR_IMAGE_INVALID_JPEG_MARKER
raise InvalidJPEG(ERR_IMAGE_INVALID_JPEG_MARKER)
segment_type = reader.read(8)
try:
for (segment_type,
segment_data) in segments(BitstreamReader(file_data, False)):
if (segment_type in {0xC0, 0xC1, 0xC2, 0xC3,
0xC5, 0XC5, 0xC6, 0xC7,
0xC9, 0xCA, 0xCB, 0xCD,
0xCE, 0xCF}): # start of frame
(data_precision,
image_height,
image_width,
components) = segment_data.parse("8u 16u 16u 8u")
return __JPEG__(width=image_width,
height=image_height,
bits_per_pixel=data_precision * components)
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_JPEG
raise InvalidJPEG(ERR_IMAGE_IOERROR_JPEG)
#######################
# PNG
#######################
class InvalidPNG(InvalidImage):
"""raised if a PNG cannot be parsed correctly"""
pass
class __PNG__(ImageMetrics):
def __init__(self, width, height, bits_per_pixel, color_count):
ImageMetrics.__init__(self, width, height, bits_per_pixel, color_count,
u'image/png')
@classmethod
def parse(cls, file_data):
def chunks(reader):
if reader.read_bytes(8) != b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A':
from audiotools.text import ERR_IMAGE_INVALID_PNG
raise InvalidPNG(ERR_IMAGE_INVALID_PNG)
(chunk_length, chunk_type) = reader.parse("32u 4b")
while chunk_type != b'IEND':
yield (chunk_type,
chunk_length,
reader.substream(chunk_length))
chunk_crc = reader.read(32)
(chunk_length, chunk_type) = reader.parse("32u 4b")
ihdr = None
plte_length = 0
try:
for (chunk_type,
chunk_length,
chunk_data) in chunks(BitstreamReader(file_data, False)):
if chunk_type == b'IHDR':
ihdr = chunk_data
elif chunk_type == b'PLTE':
plte_length = chunk_length
if ihdr is None:
from audiotools.text import ERR_IMAGE_INVALID_PNG
raise InvalidPNG(ERR_IMAGE_INVALID_PNG)
(width,
height,
bit_depth,
color_type,
compression_method,
filter_method,
interlace_method) = ihdr.parse("32u 32u 8u 8u 8u 8u 8u")
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_PNG
raise InvalidPNG(ERR_IMAGE_IOERROR_PNG)
if color_type == 0: # grayscale
return cls(width=width,
height=height,
bits_per_pixel=bit_depth,
color_count=0)
elif color_type == 2: # RGB
return cls(width=width,
height=height,
bits_per_pixel=bit_depth * 3,
color_count=0)
elif color_type == 3: # palette
if (plte_length % 3) != 0:
from audiotools.text import ERR_IMAGE_INVALID_PLTE
raise InvalidPNG(ERR_IMAGE_INVALID_PLTE)
else:
return cls(width=width,
height=height,
bits_per_pixel=8,
color_count=plte_length // 3)
elif color_type == 4: # grayscale + alpha
return cls(width=width,
height=height,
bits_per_pixel=bit_depth * 2,
color_count=0)
elif color_type == 6: # RGB + alpha
return cls(width=width,
height=height,
bits_per_pixel=bit_depth * 4,
color_count=0)
#######################
# BMP
#######################
class InvalidBMP(InvalidImage):
"""raised if a BMP cannot be parsed correctly"""
pass
class __BMP__(ImageMetrics):
def __init__(self, width, height, bits_per_pixel, color_count):
ImageMetrics.__init__(self, width, height, bits_per_pixel, color_count,
u'image/x-ms-bmp')
@classmethod
def parse(cls, file_data):
try:
(magic_number,
file_size,
data_offset,
header_size,
width,
height,
color_planes,
bits_per_pixel,
compression_method,
image_size,
horizontal_resolution,
vertical_resolution,
colors_used,
important_colors_used) = BitstreamReader(file_data, True).parse(
"2b 32u 16p 16p 32u " +
"32u 32u 32u 16u 16u 32u 32u 32u 32u 32u 32u")
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_BMP
raise InvalidBMP(ERR_IMAGE_IOERROR_BMP)
if magic_number != b'BM':
from audiotools.text import ERR_IMAGE_INVALID_BMP
raise InvalidBMP(ERR_IMAGE_INVALID_BMP)
else:
return cls(width=width,
height=height,
bits_per_pixel=bits_per_pixel,
color_count=colors_used)
#######################
# GIF
#######################
class InvalidGIF(InvalidImage):
"""raised if a GIF cannot be parsed correctly"""
pass
class __GIF__(ImageMetrics):
def __init__(self, width, height, color_count):
ImageMetrics.__init__(self, width, height, 8, color_count,
u'image/gif')
@classmethod
def parse(cls, file_data):
try:
(gif,
version,
width,
height,
color_table_size) = BitstreamReader(file_data, True).parse(
"3b 3b 16u 16u 3u 5p")
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_GIF
raise InvalidGIF(ERR_IMAGE_IOERROR_GIF)
if gif != b'GIF':
from audiotools.text import ERR_IMAGE_INVALID_GIF
raise InvalidGIF(ERR_IMAGE_INVALID_GIF)
else:
return cls(width=width,
height=height,
color_count=2 ** (color_table_size + 1))
#######################
# TIFF
#######################
class InvalidTIFF(InvalidImage):
"""raised if a TIFF cannot be parsed correctly"""
pass
class __TIFF__(ImageMetrics):
def __init__(self, width, height, bits_per_pixel, color_count):
ImageMetrics.__init__(self, width, height,
bits_per_pixel, color_count,
u'image/tiff')
@classmethod
def parse(cls, file_data):
from io import BytesIO
def tags(file, order):
while True:
reader = BitstreamReader(file, order)
# read all the tags in an IFD
tag_count = reader.read(16)
sub_reader = reader.substream(tag_count * 12)
next_ifd = reader.read(32)
for i in range(tag_count):
(tag_code,
tag_datatype,
tag_value_count) = sub_reader.parse("16u 16u 32u")
if tag_datatype == 1: # BYTE type
tag_struct = "8u" * tag_value_count
elif tag_datatype == 3: # SHORT type
tag_struct = "16u" * tag_value_count
elif tag_datatype == 4: # LONG type
tag_struct = "32u" * tag_value_count
else: # all other types
tag_struct = "4b"
if format_size(tag_struct) <= 32:
yield (tag_code, sub_reader.parse(tag_struct))
sub_reader.skip(32 - format_size(tag_struct))
else:
offset = sub_reader.read(32)
file.seek(offset, 0)
yield (tag_code,
BitstreamReader(file, order).parse(tag_struct))
if next_ifd != 0:
file.seek(next_ifd, 0)
else:
break
file = BytesIO(file_data)
try:
byte_order = file.read(2)
if byte_order == b'II':
order = 1
elif byte_order == b'MM':
order = 0
else:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
reader = BitstreamReader(file, order)
if reader.read(16) != 42:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
initial_ifd = reader.read(32)
file.seek(initial_ifd, 0)
width = 0
height = 0
bits_per_pixel = 0
color_count = 0
for (tag_id, tag_values) in tags(file, order):
if tag_id == 0x0100:
width = tag_values[0]
elif tag_id == 0x0101:
height = tag_values[0]
elif tag_id == 0x0102:
bits_per_pixel = sum(tag_values)
elif tag_id == 0x0140:
color_count = len(tag_values) // 3
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_TIFF
raise InvalidTIFF(ERR_IMAGE_IOERROR_TIFF)
return cls(width=width,
height=height,
bits_per_pixel=bits_per_pixel,
color_count=color_count)
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