414 lines
14 KiB
Python
414 lines
14 KiB
Python
import warnings
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from binascii import unhexlify
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from math import ceil
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from typing import Any, Dict, List, Tuple, Union, cast
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from ._codecs import adobe_glyphs, charset_encoding
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from ._utils import logger_warning
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from .errors import PdfReadWarning
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from .generic import DecodedStreamObject, DictionaryObject, StreamObject
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# code freely inspired from @twiggy ; see #711
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def build_char_map(
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font_name: str, space_width: float, obj: DictionaryObject
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) -> Tuple[
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str, float, Union[str, Dict[int, str]], Dict, DictionaryObject
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]: # font_type,space_width /2, encoding, cmap
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"""Determine information about a font.
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This function returns a tuple consisting of:
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font sub-type, space_width/2, encoding, map character-map, font-dictionary.
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The font-dictionary itself is suitable for the curious."""
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ft: DictionaryObject = obj["/Resources"]["/Font"][font_name] # type: ignore
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font_type: str = cast(str, ft["/Subtype"])
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space_code = 32
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encoding, space_code = parse_encoding(ft, space_code)
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map_dict, space_code, int_entry = parse_to_unicode(ft, space_code)
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# encoding can be either a string for decode (on 1,2 or a variable number of bytes) of a char table (for 1 byte only for me)
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# if empty string, it means it is than encoding field is not present and we have to select the good encoding from cmap input data
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if encoding == "":
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if -1 not in map_dict or map_dict[-1] == 1:
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# I have not been able to find any rule for no /Encoding nor /ToUnicode
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# One example shows /Symbol,bold I consider 8 bits encoding default
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encoding = "charmap"
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else:
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encoding = "utf-16-be"
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# apply rule from PDF ref 1.7 §5.9.1, 1st bullet : if cmap not empty encoding should be discarded (here transformed into identity for those characters)
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# if encoding is an str it is expected to be a identity translation
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elif isinstance(encoding, dict):
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for x in int_entry:
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if x <= 255:
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encoding[x] = chr(x)
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try:
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# override space_width with new params
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space_width = _default_fonts_space_width[cast(str, ft["/BaseFont"])]
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except Exception:
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pass
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# I conside the space_code is available on one byte
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if isinstance(space_code, str):
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try: # one byte
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sp = space_code.encode("charmap")[0]
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except Exception:
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sp = space_code.encode("utf-16-be")
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sp = sp[0] + 256 * sp[1]
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else:
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sp = space_code
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sp_width = compute_space_width(ft, sp, space_width)
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return (
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font_type,
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float(sp_width / 2),
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encoding,
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# https://github.com/python/mypy/issues/4374
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map_dict,
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ft,
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)
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# used when missing data, e.g. font def missing
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unknown_char_map: Tuple[str, float, Union[str, Dict[int, str]], Dict[Any, Any]] = (
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"Unknown",
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9999,
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dict(zip(range(256), ["<EFBFBD>"] * 256)),
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{},
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)
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_predefined_cmap: Dict[str, str] = {
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"/Identity-H": "utf-16-be",
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"/Identity-V": "utf-16-be",
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"/GB-EUC-H": "gbk", # TBC
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"/GB-EUC-V": "gbk", # TBC
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"/GBpc-EUC-H": "gb2312", # TBC
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"/GBpc-EUC-V": "gb2312", # TBC
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}
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# manually extracted from http://mirrors.ctan.org/fonts/adobe/afm/Adobe-Core35_AFMs-229.tar.gz
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_default_fonts_space_width: Dict[str, int] = {
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"/Courrier": 600,
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"/Courier-Bold": 600,
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"/Courier-BoldOblique": 600,
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"/Courier-Oblique": 600,
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"/Helvetica": 278,
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"/Helvetica-Bold": 278,
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"/Helvetica-BoldOblique": 278,
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"/Helvetica-Oblique": 278,
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"/Helvetica-Narrow": 228,
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"/Helvetica-NarrowBold": 228,
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"/Helvetica-NarrowBoldOblique": 228,
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"/Helvetica-NarrowOblique": 228,
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"/Times-Roman": 250,
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"/Times-Bold": 250,
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"/Times-BoldItalic": 250,
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"/Times-Italic": 250,
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"/Symbol": 250,
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"/ZapfDingbats": 278,
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}
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def parse_encoding(
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ft: DictionaryObject, space_code: int
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) -> Tuple[Union[str, Dict[int, str]], int]:
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encoding: Union[str, List[str], Dict[int, str]] = []
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if "/Encoding" not in ft:
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try:
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if "/BaseFont" in ft and cast(str, ft["/BaseFont"]) in charset_encoding:
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encoding = dict(
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zip(range(256), charset_encoding[cast(str, ft["/BaseFont"])])
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)
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else:
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encoding = "charmap"
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return encoding, _default_fonts_space_width[cast(str, ft["/BaseFont"])]
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except Exception:
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if cast(str, ft["/Subtype"]) == "/Type1":
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return "charmap", space_code
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else:
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return "", space_code
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enc: Union(str, DictionaryObject) = ft["/Encoding"].get_object() # type: ignore
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if isinstance(enc, str):
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try:
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# allready done : enc = NameObject.unnumber(enc.encode()).decode() # for #xx decoding
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if enc in charset_encoding:
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encoding = charset_encoding[enc].copy()
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elif enc in _predefined_cmap:
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encoding = _predefined_cmap[enc]
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else:
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raise Exception("not found")
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except Exception:
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warnings.warn(
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f"Advanced encoding {enc} not implemented yet",
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PdfReadWarning,
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)
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encoding = enc
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elif isinstance(enc, DictionaryObject) and "/BaseEncoding" in enc:
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try:
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encoding = charset_encoding[cast(str, enc["/BaseEncoding"])].copy()
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except Exception:
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warnings.warn(
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f"Advanced encoding {encoding} not implemented yet",
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PdfReadWarning,
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)
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encoding = charset_encoding["/StandardCoding"].copy()
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else:
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encoding = charset_encoding["/StandardCoding"].copy()
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if "/Differences" in enc:
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x: int = 0
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o: Union[int, str]
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for o in cast(DictionaryObject, cast(DictionaryObject, enc)["/Differences"]):
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if isinstance(o, int):
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x = o
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else: # isinstance(o,str):
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try:
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encoding[x] = adobe_glyphs[o] # type: ignore
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except Exception:
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encoding[x] = o # type: ignore
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if o == " ":
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space_code = x
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x += 1
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if isinstance(encoding, list):
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encoding = dict(zip(range(256), encoding))
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return encoding, space_code
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def parse_to_unicode(
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ft: DictionaryObject, space_code: int
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) -> Tuple[Dict[Any, Any], int, List[int]]:
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# will store all translation code
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# and map_dict[-1] we will have the number of bytes to convert
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map_dict: Dict[Any, Any] = {}
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# will provide the list of cmap keys as int to correct encoding
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int_entry: List[int] = []
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if "/ToUnicode" not in ft:
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return {}, space_code, []
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process_rg: bool = False
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process_char: bool = False
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multiline_rg: Union[
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None, Tuple[int, int]
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] = None # tuple = (current_char, remaining size) ; cf #1285 for example of file
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cm = prepare_cm(ft)
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for l in cm.split(b"\n"):
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process_rg, process_char, multiline_rg = process_cm_line(
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l.strip(b" "), process_rg, process_char, multiline_rg, map_dict, int_entry
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)
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for a, value in map_dict.items():
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if value == " ":
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space_code = a
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return map_dict, space_code, int_entry
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def prepare_cm(ft: DictionaryObject) -> bytes:
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tu = ft["/ToUnicode"]
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cm: bytes
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if isinstance(tu, StreamObject):
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cm = cast(DecodedStreamObject, ft["/ToUnicode"]).get_data()
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elif isinstance(tu, str) and tu.startswith("/Identity"):
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cm = b"beginbfrange\n<0000> <0001> <0000>\nendbfrange" # the full range 0000-FFFF will be processed
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if isinstance(cm, str):
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cm = cm.encode()
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# we need to prepare cm before due to missing return line in pdf printed to pdf from word
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cm = (
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cm.strip()
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.replace(b"beginbfchar", b"\nbeginbfchar\n")
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.replace(b"endbfchar", b"\nendbfchar\n")
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.replace(b"beginbfrange", b"\nbeginbfrange\n")
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.replace(b"endbfrange", b"\nendbfrange\n")
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.replace(b"<<", b"\n{\n") # text between << and >> not used but
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.replace(b">>", b"\n}\n") # some solution to find it back
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)
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ll = cm.split(b"<")
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for i in range(len(ll)):
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j = ll[i].find(b">")
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if j >= 0:
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if j == 0:
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# string is empty: stash a placeholder here (see below)
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# see https://github.com/py-pdf/PyPDF2/issues/1111
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content = b"."
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else:
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content = ll[i][:j].replace(b" ", b"")
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ll[i] = content + b" " + ll[i][j + 1 :]
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cm = (
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(b" ".join(ll))
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.replace(b"[", b" [ ")
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.replace(b"]", b" ]\n ")
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.replace(b"\r", b"\n")
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)
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return cm
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def process_cm_line(
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l: bytes,
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process_rg: bool,
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process_char: bool,
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multiline_rg: Union[None, Tuple[int, int]],
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map_dict: Dict[Any, Any],
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int_entry: List[int],
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) -> Tuple[bool, bool, Union[None, Tuple[int, int]]]:
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if l in (b"", b" ") or l[0] == 37: # 37 = %
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return process_rg, process_char, multiline_rg
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if b"beginbfrange" in l:
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process_rg = True
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elif b"endbfrange" in l:
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process_rg = False
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elif b"beginbfchar" in l:
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process_char = True
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elif b"endbfchar" in l:
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process_char = False
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elif process_rg:
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multiline_rg = parse_bfrange(l, map_dict, int_entry, multiline_rg)
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elif process_char:
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parse_bfchar(l, map_dict, int_entry)
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return process_rg, process_char, multiline_rg
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def parse_bfrange(
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l: bytes,
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map_dict: Dict[Any, Any],
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int_entry: List[int],
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multiline_rg: Union[None, Tuple[int, int]],
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) -> Union[None, Tuple[int, int]]:
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lst = [x for x in l.split(b" ") if x]
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closure_found = False
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nbi = max(len(lst[0]), len(lst[1]))
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map_dict[-1] = ceil(nbi / 2)
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fmt = b"%%0%dX" % (map_dict[-1] * 2)
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if multiline_rg is not None:
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a = multiline_rg[0] # a, b not in the current line
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b = multiline_rg[1]
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for sq in lst[1:]:
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if sq == b"]":
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closure_found = True
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break
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map_dict[
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unhexlify(fmt % a).decode(
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"charmap" if map_dict[-1] == 1 else "utf-16-be",
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"surrogatepass",
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)
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] = unhexlify(sq).decode("utf-16-be", "surrogatepass")
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int_entry.append(a)
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a += 1
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else:
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a = int(lst[0], 16)
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b = int(lst[1], 16)
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if lst[2] == b"[":
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for sq in lst[3:]:
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if sq == b"]":
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closure_found = True
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break
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map_dict[
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unhexlify(fmt % a).decode(
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"charmap" if map_dict[-1] == 1 else "utf-16-be",
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"surrogatepass",
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)
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] = unhexlify(sq).decode("utf-16-be", "surrogatepass")
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int_entry.append(a)
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a += 1
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else: # case without list
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c = int(lst[2], 16)
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fmt2 = b"%%0%dX" % max(4, len(lst[2]))
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closure_found = True
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while a <= b:
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map_dict[
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unhexlify(fmt % a).decode(
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"charmap" if map_dict[-1] == 1 else "utf-16-be",
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"surrogatepass",
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)
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] = unhexlify(fmt2 % c).decode("utf-16-be", "surrogatepass")
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int_entry.append(a)
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a += 1
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c += 1
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return None if closure_found else (a, b)
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def parse_bfchar(l: bytes, map_dict: Dict[Any, Any], int_entry: List[int]) -> None:
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lst = [x for x in l.split(b" ") if x]
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map_dict[-1] = len(lst[0]) // 2
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while len(lst) > 1:
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map_to = ""
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# placeholder (see above) means empty string
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if lst[1] != b".":
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map_to = unhexlify(lst[1]).decode(
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"charmap" if len(lst[1]) < 4 else "utf-16-be", "surrogatepass"
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) # join is here as some cases where the code was split
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map_dict[
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unhexlify(lst[0]).decode(
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"charmap" if map_dict[-1] == 1 else "utf-16-be", "surrogatepass"
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)
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] = map_to
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int_entry.append(int(lst[0], 16))
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lst = lst[2:]
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def compute_space_width(
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ft: DictionaryObject, space_code: int, space_width: float
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) -> float:
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sp_width: float = space_width * 2 # default value
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w = []
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w1 = {}
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st: int = 0
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if "/DescendantFonts" in ft: # ft["/Subtype"].startswith("/CIDFontType"):
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ft1 = ft["/DescendantFonts"][0].get_object() # type: ignore
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try:
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w1[-1] = cast(float, ft1["/DW"])
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except Exception:
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w1[-1] = 1000.0
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if "/W" in ft1:
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w = list(ft1["/W"])
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else:
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w = []
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while len(w) > 0:
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st = w[0]
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second = w[1]
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if isinstance(second, int):
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for x in range(st, second):
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w1[x] = w[2]
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w = w[3:]
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elif isinstance(second, list):
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for y in second:
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w1[st] = y
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st += 1
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w = w[2:]
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else:
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logger_warning(
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"unknown widths : \n" + (ft1["/W"]).__repr__(),
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__name__,
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)
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break
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try:
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sp_width = w1[space_code]
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except Exception:
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sp_width = (
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w1[-1] / 2.0
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) # if using default we consider space will be only half size
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elif "/Widths" in ft:
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w = list(ft["/Widths"]) # type: ignore
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try:
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st = cast(int, ft["/FirstChar"])
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en: int = cast(int, ft["/LastChar"])
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if st > space_code or en < space_code:
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raise Exception("Not in range")
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if w[space_code - st] == 0:
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raise Exception("null width")
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sp_width = w[space_code - st]
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except Exception:
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if "/FontDescriptor" in ft and "/MissingWidth" in cast(
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DictionaryObject, ft["/FontDescriptor"]
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):
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sp_width = ft["/FontDescriptor"]["/MissingWidth"] # type: ignore
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else:
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# will consider width of char as avg(width)/2
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m = 0
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cpt = 0
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for x in w:
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if x > 0:
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m += x
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cpt += 1
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sp_width = m / max(1, cpt) / 2
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return sp_width
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