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info.py: linearize O(n^2) search for use images on a page

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James R. Barlow 2020-03-18 22:59:18 -07:00
parent 82142fe5ef
commit f35a2303bb
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GPG Key ID: 4434EB74C4A35F7F
1 changed files with 8 additions and 9 deletions
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17
src/ocrmypdf/pdfinfo/info.py
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@ -18,7 +18,7 @@
import logging
import re
from collections import namedtuple
from collections import defaultdict, namedtuple
from decimal import Decimal
from enum import Enum
from math import hypot, isclose
@ -98,7 +98,7 @@ XobjectSettings = namedtuple('XobjectSettings', ['name', 'shorthand', 'stack_dep
InlineSettings = namedtuple('InlineSettings', ['iimage', 'shorthand', 'stack_depth'])
ContentsInfo = namedtuple(
'ContentsInfo', ['xobject_settings', 'inline_images', 'found_vector']
'ContentsInfo', ['xobject_settings', 'inline_images', 'found_vector', 'name_index']
)
TextboxInfo = namedtuple('TextboxInfo', ['bbox', 'is_visible', 'is_corrupt'])
@ -151,6 +151,7 @@ def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
ctm = PdfMatrix(initial_shorthand)
xobject_settings = []
inline_images = []
name_index = defaultdict(lambda: [])
found_vector = False
vector_ops = set('S s f F f* B B* b b*'.split())
image_ops = set('BI ID EI q Q Do cm'.split())
@ -185,6 +186,7 @@ def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
name=image_name, shorthand=ctm.shorthand, stack_depth=len(stack)
)
xobject_settings.append(settings)
name_index[image_name].append(settings)
elif operator == 'INLINE IMAGE': # BI/ID/EI are grouped into this
iimage = operands[0]
inline = InlineSettings(
@ -198,6 +200,7 @@ def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
xobject_settings=xobject_settings,
inline_images=inline_images,
found_vector=found_vector,
name_index=name_index,
)
@ -419,13 +422,9 @@ def _find_regular_images(container, contentsinfo):
"""
for pdfimage, xobj in _image_xobjects(container):
# For each image that is drawn on this, check if we drawing the
# current image - yes this is O(n^2), but n == 1 almost always
for draw in contentsinfo.xobject_settings:
if draw.name != xobj:
continue
if xobj not in contentsinfo.name_index:
continue
for draw in contentsinfo.name_index[xobj]:
if draw.stack_depth == 0 and _is_unit_square(draw.shorthand):
# At least one PDF in the wild (and test suite) draws an image
# when the graphics stack depth is 0, meaning that the image