168 lines
6.3 KiB
Python
168 lines
6.3 KiB
Python
import logging
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from pdfminer.utils import Rect
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from typing import BinaryIO, Container, Dict, Iterator, List, Optional, Tuple
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import warnings
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from . import settings
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from .psparser import LIT
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from .pdftypes import PDFObjectNotFound
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from .pdftypes import resolve1
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from .pdftypes import int_value
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from .pdftypes import list_value
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from .pdftypes import dict_value
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from .pdfparser import PDFParser
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from .pdfdocument import PDFDocument, PDFTextExtractionNotAllowed
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from .pdfdocument import PDFTextExtractionNotAllowedWarning
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log = logging.getLogger(__name__)
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# some predefined literals and keywords.
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LITERAL_PAGE = LIT('Page')
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LITERAL_PAGES = LIT('Pages')
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class PDFPage:
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"""An object that holds the information about a page.
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A PDFPage object is merely a convenience class that has a set
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of keys and values, which describe the properties of a page
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and point to its contents.
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Attributes:
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doc: a PDFDocument object.
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pageid: any Python object that can uniquely identify the page.
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attrs: a dictionary of page attributes.
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contents: a list of PDFStream objects that represents the page content.
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lastmod: the last modified time of the page.
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resources: a dictionary of resources used by the page.
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mediabox: the physical size of the page.
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cropbox: the crop rectangle of the page.
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rotate: the page rotation (in degree).
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annots: the page annotations.
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beads: a chain that represents natural reading order.
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"""
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def __init__(
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self,
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doc: PDFDocument,
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pageid: object,
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attrs: object
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) -> None:
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"""Initialize a page object.
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doc: a PDFDocument object.
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pageid: any Python object that can uniquely identify the page.
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attrs: a dictionary of page attributes.
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"""
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self.doc = doc
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self.pageid = pageid
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self.attrs = dict_value(attrs)
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self.lastmod = resolve1(self.attrs.get('LastModified'))
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self.resources: Dict[object, object] = \
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resolve1(self.attrs.get('Resources', dict()))
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self.mediabox: Rect = resolve1(self.attrs['MediaBox'])
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if 'CropBox' in self.attrs:
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self.cropbox: Rect = resolve1(self.attrs['CropBox'])
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else:
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self.cropbox = self.mediabox
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self.rotate = (int_value(self.attrs.get('Rotate', 0))+360) % 360
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self.annots = self.attrs.get('Annots')
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self.beads = self.attrs.get('B')
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if 'Contents' in self.attrs:
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contents = resolve1(self.attrs['Contents'])
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else:
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contents = []
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if not isinstance(contents, list):
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contents = [contents]
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self.contents: List[object] = contents
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return
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def __repr__(self) -> str:
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return '<PDFPage: Resources={!r}, MediaBox={!r}>'\
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.format(self.resources, self.mediabox)
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INHERITABLE_ATTRS = {'Resources', 'MediaBox', 'CropBox', 'Rotate'}
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@classmethod
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def create_pages(cls, document: PDFDocument) -> Iterator["PDFPage"]:
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def search(
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obj: object,
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parent: Dict[str, object]
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) -> Iterator[Tuple[int, Dict[object, Dict[object, object]]]]:
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if isinstance(obj, int):
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objid = obj
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tree = dict_value(document.getobj(objid)).copy()
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else:
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# This looks broken. obj.objid means obj could be either
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# PDFObjRef or PDFStream, but neither is valid for dict_value.
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objid = obj.objid # type: ignore[attr-defined]
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tree = dict_value(obj).copy()
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for (k, v) in parent.items():
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if k in cls.INHERITABLE_ATTRS and k not in tree:
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tree[k] = v
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tree_type = tree.get('Type')
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if tree_type is None and not settings.STRICT: # See #64
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tree_type = tree.get('type')
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if tree_type is LITERAL_PAGES and 'Kids' in tree:
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log.info('Pages: Kids=%r', tree['Kids'])
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for c in list_value(tree['Kids']):
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yield from search(c, tree)
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elif tree_type is LITERAL_PAGE:
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log.info('Page: %r', tree)
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yield (objid, tree)
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pages = False
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if 'Pages' in document.catalog:
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objects = search(document.catalog['Pages'], document.catalog)
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for (objid, tree) in objects:
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yield cls(document, objid, tree)
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pages = True
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if not pages:
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# fallback when /Pages is missing.
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for xref in document.xrefs:
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for objid in xref.get_objids():
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try:
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obj = document.getobj(objid)
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if isinstance(obj, dict) \
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and obj.get('Type') is LITERAL_PAGE:
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yield cls(document, objid, obj)
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except PDFObjectNotFound:
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pass
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return
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@classmethod
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def get_pages(
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cls,
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fp: BinaryIO,
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pagenos: Optional[Container[int]] = None,
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maxpages: int = 0,
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password: str = '',
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caching: bool = True,
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check_extractable: bool = False
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) -> Iterator["PDFPage"]:
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# Create a PDF parser object associated with the file object.
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parser = PDFParser(fp)
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# Create a PDF document object that stores the document structure.
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doc = PDFDocument(parser, password=password, caching=caching)
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# Check if the document allows text extraction.
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# If not, warn the user and proceed.
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if not doc.is_extractable:
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if check_extractable:
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error_msg = 'Text extraction is not allowed: %r' % fp
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raise PDFTextExtractionNotAllowed(error_msg)
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else:
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warning_msg = 'The PDF %r contains a metadata field '\
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'indicating that it should not allow ' \
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'text extraction. Ignoring this field ' \
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'and proceeding.' % fp
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warnings.warn(warning_msg, PDFTextExtractionNotAllowedWarning)
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# Process each page contained in the document.
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for (pageno, page) in enumerate(cls.create_pages(doc)):
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if pagenos and (pageno not in pagenos):
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continue
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yield page
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if maxpages and maxpages <= pageno+1:
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break
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return
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