95 lines
2.6 KiB
Python
95 lines
2.6 KiB
Python
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import struct
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from ._exceptions import InvalidImageDataError
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def split_into_segments(data):
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"""Slices JPEG meta data into a list from JPEG binary data.
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"""
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if data[0:2] != b"\xff\xd8":
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raise InvalidImageDataError("Given data isn't JPEG.")
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head = 2
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segments = [b"\xff\xd8"]
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while 1:
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if data[head: head + 2] == b"\xff\xda":
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segments.append(data[head:])
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break
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else:
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length = struct.unpack(">H", data[head + 2: head + 4])[0]
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endPoint = head + length + 2
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seg = data[head: endPoint]
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segments.append(seg)
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head = endPoint
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if (head >= len(data)):
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raise InvalidImageDataError("Wrong JPEG data.")
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return segments
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def read_exif_from_file(filename):
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"""Slices JPEG meta data into a list from JPEG binary data.
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"""
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f = open(filename, "rb")
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data = f.read(6)
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if data[0:2] != b"\xff\xd8":
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raise InvalidImageDataError("Given data isn't JPEG.")
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head = data[2:6]
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HEAD_LENGTH = 4
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exif = None
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while len(head) == HEAD_LENGTH:
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length = struct.unpack(">H", head[2: 4])[0]
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if head[:2] == b"\xff\xe1":
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segment_data = f.read(length - 2)
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if segment_data[:4] != b'Exif':
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head = f.read(HEAD_LENGTH)
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continue
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exif = head + segment_data
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break
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elif head[0:1] == b"\xff":
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f.read(length - 2)
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head = f.read(HEAD_LENGTH)
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else:
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break
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f.close()
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return exif
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def get_exif_seg(segments):
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"""Returns Exif from JPEG meta data list
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"""
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for seg in segments:
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if seg[0:2] == b"\xff\xe1" and seg[4:10] == b"Exif\x00\x00":
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return seg
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return None
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def merge_segments(segments, exif=b""):
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"""Merges Exif with APP0 and APP1 manipulations.
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"""
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if segments[1][0:2] == b"\xff\xe0" and \
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segments[2][0:2] == b"\xff\xe1" and \
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segments[2][4:10] == b"Exif\x00\x00":
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if exif:
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segments[2] = exif
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segments.pop(1)
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elif exif is None:
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segments.pop(2)
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else:
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segments.pop(1)
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elif segments[1][0:2] == b"\xff\xe0":
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if exif:
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segments[1] = exif
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elif segments[1][0:2] == b"\xff\xe1" and \
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segments[1][4:10] == b"Exif\x00\x00":
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if exif:
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segments[1] = exif
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elif exif is None:
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segments.pop(1)
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else:
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if exif:
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segments.insert(1, exif)
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return b"".join(segments)
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