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ROB: improve inline image extraction
closes py-pdf#2598
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,242 @@ | ||
| # Copyright (c) 2024, PubPub-ZZ | ||
| # All rights reserved. | ||
| # | ||
| # Redistribution and use in source and binary forms, with or without | ||
| # modification, are permitted provided that the following conditions are | ||
| # met: | ||
| # | ||
| # * Redistributions of source code must retain the above copyright notice, | ||
| # this list of conditions and the following disclaimer. | ||
| # * Redistributions in binary form must reproduce the above copyright notice, | ||
| # this list of conditions and the following disclaimer in the documentation | ||
| # and/or other materials provided with the distribution. | ||
| # * The name of the author may not be used to endorse or promote products | ||
| # derived from this software without specific prior written permission. | ||
| # | ||
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
| # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
| # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
| # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | ||
| # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | ||
| # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | ||
| # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | ||
| # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||
| # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | ||
| # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||
| # POSSIBILITY OF SUCH DAMAGE. | ||
|
|
||
| import logging | ||
| from io import BytesIO | ||
|
|
||
| from .._utils import ( | ||
| WHITESPACES, | ||
| StreamType, | ||
| read_non_whitespace, | ||
| ) | ||
| from ..errors import PdfReadError | ||
|
|
||
| logger = logging.getLogger(__name__) | ||
|
|
||
| BUFFER_SIZE = 8192 | ||
|
|
||
|
|
||
| def extract_inline_AHex(stream: StreamType) -> bytes: | ||
| """ | ||
| Extract HexEncoded Stream from Inline Image. | ||
| the stream will be moved onto the EI | ||
| """ | ||
| data: bytes = b"" | ||
| # Read data until delimiter > and EI as backup | ||
| # ignoring backup. | ||
| while True: | ||
| buf = stream.read(BUFFER_SIZE) | ||
| if not buf: | ||
| raise PdfReadError("Unexpected end of stream") | ||
| loc = buf.find(b">") | ||
| if loc >= 0: # found > | ||
| data += buf[: (loc + 1)] | ||
| stream.seek(-BUFFER_SIZE + loc + 1) | ||
| break | ||
| loc = buf.find(b"EI") | ||
| if loc >= 0: # found EI | ||
| stream.seek(-BUFFER_SIZE + loc - 1, 1) | ||
| c = stream.read(1) | ||
| while c in WHITESPACES: | ||
| stream.seek(-2, 1) | ||
| c = stream.read(1) | ||
| loc -= 1 | ||
| data += buf[:loc] | ||
| else: # > nor EI found | ||
| data += buf[:-1] | ||
| stream.seek(-1, 1) | ||
|
|
||
| ei = read_non_whitespace(stream) | ||
| ei += stream.read(1) | ||
| stream.seek(-2, 1) | ||
| if ei != b"EI": | ||
| raise PdfReadError("EI stream not found") | ||
| return data | ||
|
|
||
|
|
||
| def extract_inline_A85(stream: StreamType) -> bytes: | ||
| """ | ||
| Extract A85 Stream from Inline Image. | ||
| the stream will be moved onto the EI | ||
| """ | ||
| data: bytes = b"" | ||
| # Read data up to delimiter ~> | ||
| # see §3.3.2 from PDF ref 1.7 | ||
| while True: | ||
| buf = stream.read(BUFFER_SIZE) | ||
| if not buf: | ||
| raise PdfReadError("Unexpected end of stream") | ||
| loc = buf.find(b"~>") | ||
| if loc >= 0: # found! | ||
| data += buf[: loc + 2] | ||
| stream.seek(-BUFFER_SIZE + loc + 2, 1) | ||
| break | ||
| data += buf[:-1] # back by one char in case of in the middle of ~> | ||
| stream.seek(-1, 1) | ||
|
|
||
| ei = read_non_whitespace(stream) | ||
| ei += stream.read(1) | ||
| stream.seek(-2, 1) | ||
| if ei != b"EI": | ||
| raise PdfReadError("EI stream not found") | ||
| return data | ||
|
|
||
|
|
||
| def extract_inline_RL(stream: StreamType) -> bytes: | ||
| """ | ||
| Extract RL Stream from Inline Image. | ||
| the stream will be moved onto the EI | ||
| """ | ||
| data: bytes = b"" | ||
| # Read data up to delimiter ~> | ||
| # see §3.3.4 from PDF ref 1.7 | ||
| while True: | ||
| buf = stream.read(BUFFER_SIZE) | ||
| if not buf: | ||
| raise PdfReadError("Unexpected end of stream") | ||
| loc = buf.find(b"\x80") | ||
| if loc >= 0: # found | ||
| data = buf[: loc + 1] | ||
| stream.seek(-BUFFER_SIZE + loc + 1, 1) | ||
| break | ||
| data += buf # back by one char in case of in the middle of ~> | ||
|
|
||
| data += buf[:loc] | ||
| ei = read_non_whitespace(stream) | ||
| ei += stream.read(1) | ||
| stream.seek(-2, 1) | ||
| if ei != b"EI": | ||
| raise PdfReadError("EI stream not found") | ||
| return data | ||
|
|
||
|
|
||
| def extract_inline_DCT(stream: StreamType) -> bytes: | ||
| """ | ||
| Extract DCT (JPEG) Stream from Inline Image. | ||
| the stream will be moved onto the EI | ||
| """ | ||
| data: bytes = b"" | ||
| # Read Blocks of data (ID/Size/data) up to ID=FF/D9 | ||
| # see https://www.digicamsoft.com/itu/itu-t81-36.html | ||
| while True: | ||
| c = stream.read(1) | ||
| data += c | ||
| if c != b"\xff": | ||
| continue | ||
| c = stream.read(1) | ||
| if c == b"\xff": | ||
| stream.seek(-1, 1) | ||
| elif c == b"\x00": # stuffing | ||
| data += c | ||
| elif c == b"\xd9": # end | ||
| data += c | ||
| break | ||
| elif c in ( | ||
| b"\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc9\xca\xcb\xcc\xcd\xce\xcf" | ||
| b"\xda\xdb\xdc\xdd\xde\xdf" | ||
| b"\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xfe" | ||
| ): | ||
| data += c | ||
| c = stream.read(2) | ||
| data += c | ||
| sz = ord(c[0]) * 256 + c[1] | ||
| data += stream.read(sz - 2) | ||
| else: | ||
| data += c | ||
|
|
||
| ei = read_non_whitespace(stream) | ||
| ei += stream.read(1) | ||
| stream.seek(-2, 1) | ||
| if ei != b"EI": | ||
| raise PdfReadError("EI stream not found") | ||
| return data | ||
|
|
||
|
|
||
| def extract_inline_default(stream: StreamType) -> bytes: | ||
| """ | ||
| Legacy method | ||
| used by default | ||
| """ | ||
| data = BytesIO() | ||
| # Read the inline image, while checking for EI (End Image) operator. | ||
| while True: | ||
| buf = stream.read(BUFFER_SIZE) | ||
| if not buf: | ||
| raise PdfReadError("Unexpected end of stream") | ||
| loc = buf.find( | ||
| b"E" | ||
| ) # we can not look straight for "EI" because it may not have been loaded in the buffer | ||
|
|
||
| if loc == -1: | ||
| data.write(buf) | ||
| else: | ||
| # Write out everything before the E. | ||
| data.write(buf[0:loc]) | ||
|
|
||
| # Seek back in the stream to read the E next. | ||
| stream.seek(loc - len(buf), 1) | ||
| saved_pos = stream.tell() | ||
| tok = stream.read(1) # E of "EI" | ||
| # Check for End Image | ||
| tok2 = stream.read(1) # I of "EI" | ||
| if tok2 != b"I": | ||
| stream.seek(-1, 1) | ||
| data.write(tok) | ||
| continue | ||
| # for further debug : print("!!!!",buf[loc-1:loc+10]) | ||
| info = tok + tok2 | ||
| tok3 = stream.read( | ||
| 1 | ||
| ) # possible space after "EI" may not been loaded in buf | ||
| if tok3 not in WHITESPACES: | ||
| stream.seek(-2, 1) # to step back on I | ||
| data.write(tok) | ||
| elif buf[loc - 1 : loc] in WHITESPACES: # and tok3 in WHITESPACES: | ||
| # Data can contain [\s]EI[\s]: 4 chars sufficient, checking Q operator not required. | ||
| while tok3 in WHITESPACES: | ||
| # needed ???? : info += tok3 | ||
| tok3 = stream.read(1) | ||
| stream.seek(-1, 1) | ||
| # we do not insert EI | ||
| break | ||
| else: # buf[loc - 1 : loc] not in WHITESPACES and tok3 in WHITESPACES: | ||
| # Data can contain [!\s]EI[\s], so check for Q or EMC operator is required to have 4 chars. | ||
| while tok3 in WHITESPACES: | ||
| info += tok3 | ||
| tok3 = stream.read(1) | ||
| stream.seek(-1, 1) | ||
| if tok3 == b"Q": | ||
| break | ||
| elif tok3 == b"E": | ||
| ope = stream.read(3) | ||
| stream.seek(-3, 1) | ||
| if ope == b"EMC": | ||
| break | ||
| else: | ||
| data.write(info) | ||
| stream.seek(saved_pos, 0) | ||
| return data.getvalue() |
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