532 lines
17 KiB
Python
532 lines
17 KiB
Python
"""
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Miscellaneous Routines.
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"""
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import io
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import pathlib
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import struct
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from typing import (Any, BinaryIO, Callable, Dict, Generic, Iterable, Iterator,
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List, Optional, Set, TextIO, Tuple, TypeVar, Union,
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TYPE_CHECKING, cast)
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from typing_extensions import Literal
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from html import escape
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if TYPE_CHECKING:
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from .layout import LTComponent
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import chardet # For str encoding detection
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# from sys import maxint as INF doesn't work anymore under Python3, but PDF
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# still uses 32 bits ints
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INF = (1 << 31) - 1
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FileOrName = Union[pathlib.PurePath, str, io.IOBase]
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AnyIO = Union[TextIO, BinaryIO]
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class open_filename(object):
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"""
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Context manager that allows opening a filename
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(str or pathlib.PurePath type is supported) and closes it on exit,
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(just like `open`), but does nothing for file-like objects.
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"""
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def __init__(
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self,
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filename: FileOrName,
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*args: Any,
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**kwargs: Any
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) -> None:
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if isinstance(filename, pathlib.PurePath):
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filename = str(filename)
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if isinstance(filename, str):
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self.file_handler: AnyIO = open(filename, *args, **kwargs)
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self.closing = True
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elif isinstance(filename, io.IOBase):
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self.file_handler = cast(AnyIO, filename)
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self.closing = False
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else:
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raise TypeError('Unsupported input type: %s' % type(filename))
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def __enter__(self) -> AnyIO:
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return self.file_handler
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def __exit__(
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self,
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exc_type: object,
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exc_val: object,
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exc_tb: object
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) -> Literal[False]:
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if self.closing:
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self.file_handler.close()
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return False
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def make_compat_bytes(in_str: str) -> bytes:
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"Converts to bytes, encoding to unicode."
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assert isinstance(in_str, str), str(type(in_str))
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return in_str.encode()
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def make_compat_str(o: object) -> str:
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"""Converts everything to string, if bytes guessing the encoding."""
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if isinstance(o, bytes):
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enc = chardet.detect(o)
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return o.decode(enc['encoding'])
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else:
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return str(o)
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def shorten_str(s: str, size: int) -> str:
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if size < 7:
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return s[:size]
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if len(s) > size:
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length = (size - 5) // 2
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return '{} ... {}'.format(s[:length], s[-length:])
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else:
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return s
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def compatible_encode_method(
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bytesorstring: Union[bytes, str],
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encoding: str = 'utf-8',
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erraction: str = 'ignore'
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) -> str:
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"""When Py2 str.encode is called, it often means bytes.encode in Py3.
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This does either.
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"""
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if isinstance(bytesorstring, str):
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return bytesorstring
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assert isinstance(bytesorstring, bytes), str(type(bytesorstring))
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return bytesorstring.decode(encoding, erraction)
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def paeth_predictor(left: int, above: int, upper_left: int) -> int:
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# From http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
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# Initial estimate
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p = left + above - upper_left
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# Distances to a,b,c
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pa = abs(p - left)
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pb = abs(p - above)
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pc = abs(p - upper_left)
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# Return nearest of a,b,c breaking ties in order a,b,c
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if pa <= pb and pa <= pc:
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return left
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elif pb <= pc:
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return above
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else:
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return upper_left
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def apply_png_predictor(
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pred: int,
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colors: int,
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columns: int,
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bitspercomponent: int,
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data: bytes
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) -> bytes:
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"""Reverse the effect of the PNG predictor
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Documentation: http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
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"""
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if bitspercomponent != 8:
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msg = "Unsupported `bitspercomponent': %d" % bitspercomponent
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raise ValueError(msg)
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nbytes = colors * columns * bitspercomponent // 8
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bpp = colors * bitspercomponent // 8 # number of bytes per complete pixel
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buf = b''
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line_above = b'\x00' * columns
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for scanline_i in range(0, len(data), nbytes + 1):
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filter_type = data[scanline_i]
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line_encoded = data[scanline_i + 1:scanline_i + 1 + nbytes]
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raw = b''
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if filter_type == 0:
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# Filter type 0: None
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raw += line_encoded
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elif filter_type == 1:
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# Filter type 1: Sub
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# To reverse the effect of the Sub() filter after decompression,
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# output the following value:
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# Raw(x) = Sub(x) + Raw(x - bpp)
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# (computed mod 256), where Raw() refers to the bytes already
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# decoded.
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for j, sub_x in enumerate(line_encoded):
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if j - bpp < 0:
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raw_x_bpp = 0
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else:
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raw_x_bpp = int(raw[j - bpp])
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raw_x = (sub_x + raw_x_bpp) & 255
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raw += bytes((raw_x,))
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elif filter_type == 2:
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# Filter type 2: Up
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# To reverse the effect of the Up() filter after decompression,
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# output the following value:
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# Raw(x) = Up(x) + Prior(x)
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# (computed mod 256), where Prior() refers to the decoded bytes of
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# the prior scanline.
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for (up_x, prior_x) in zip(line_encoded, line_above):
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raw_x = (up_x + prior_x) & 255
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raw += bytes((raw_x,))
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elif filter_type == 3:
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# Filter type 3: Average
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# To reverse the effect of the Average() filter after
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# decompression, output the following value:
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# Raw(x) = Average(x) + floor((Raw(x-bpp)+Prior(x))/2)
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# where the result is computed mod 256, but the prediction is
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# calculated in the same way as for encoding. Raw() refers to the
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# bytes already decoded, and Prior() refers to the decoded bytes of
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# the prior scanline.
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for j, average_x in enumerate(line_encoded):
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if j - bpp < 0:
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raw_x_bpp = 0
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else:
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raw_x_bpp = int(raw[j - bpp])
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prior_x = int(line_above[j])
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raw_x = (average_x + (raw_x_bpp + prior_x) // 2) & 255
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raw += bytes((raw_x,))
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elif filter_type == 4:
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# Filter type 4: Paeth
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# To reverse the effect of the Paeth() filter after decompression,
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# output the following value:
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# Raw(x) = Paeth(x)
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# + PaethPredictor(Raw(x-bpp), Prior(x), Prior(x-bpp))
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# (computed mod 256), where Raw() and Prior() refer to bytes
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# already decoded. Exactly the same PaethPredictor() function is
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# used by both encoder and decoder.
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for j, paeth_x in enumerate(line_encoded):
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if j - bpp < 0:
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raw_x_bpp = 0
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prior_x_bpp = 0
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else:
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raw_x_bpp = int(raw[j - bpp])
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prior_x_bpp = int(line_above[j - bpp])
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prior_x = int(line_above[j])
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paeth = paeth_predictor(raw_x_bpp, prior_x, prior_x_bpp)
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raw_x = (paeth_x + paeth) & 255
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raw += bytes((raw_x,))
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else:
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raise ValueError("Unsupported predictor value: %d" % filter_type)
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buf += raw
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line_above = raw
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return buf
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Point = Tuple[float, float]
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Rect = Tuple[float, float, float, float]
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Matrix = Tuple[float, float, float, float, float, float]
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PathSegment = Union[
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Tuple[str], # Literal['h']
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Tuple[str, float, float], # Literal['m', 'l']
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Tuple[str, float, float, float, float], # Literal['v', 'y']
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Tuple[str, float, float, float, float, float, float]] # Literal['c']
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# Matrix operations
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MATRIX_IDENTITY: Matrix = (1, 0, 0, 1, 0, 0)
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def mult_matrix(m1: Matrix, m0: Matrix) -> Matrix:
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(a1, b1, c1, d1, e1, f1) = m1
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(a0, b0, c0, d0, e0, f0) = m0
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"""Returns the multiplication of two matrices."""
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return (a0 * a1 + c0 * b1, b0 * a1 + d0 * b1,
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a0 * c1 + c0 * d1, b0 * c1 + d0 * d1,
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a0 * e1 + c0 * f1 + e0, b0 * e1 + d0 * f1 + f0)
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def translate_matrix(m: Matrix, v: Point) -> Matrix:
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"""Translates a matrix by (x, y)."""
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(a, b, c, d, e, f) = m
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(x, y) = v
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return a, b, c, d, x * a + y * c + e, x * b + y * d + f
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def apply_matrix_pt(m: Matrix, v: Point) -> Point:
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(a, b, c, d, e, f) = m
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(x, y) = v
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"""Applies a matrix to a point."""
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return a * x + c * y + e, b * x + d * y + f
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def apply_matrix_norm(m: Matrix, v: Point) -> Point:
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"""Equivalent to apply_matrix_pt(M, (p,q)) - apply_matrix_pt(M, (0,0))"""
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(a, b, c, d, e, f) = m
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(p, q) = v
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return a * p + c * q, b * p + d * q
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# Utility functions
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def isnumber(x: object) -> bool:
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return isinstance(x, (int, float))
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_T = TypeVar('_T')
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def uniq(objs: Iterable[_T]) -> Iterator[_T]:
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"""Eliminates duplicated elements."""
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done = set()
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for obj in objs:
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if obj in done:
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continue
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done.add(obj)
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yield obj
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return
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def fsplit(
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pred: Callable[[_T], bool],
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objs: Iterable[_T]
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) -> Tuple[List[_T], List[_T]]:
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"""Split a list into two classes according to the predicate."""
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t = []
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f = []
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for obj in objs:
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if pred(obj):
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t.append(obj)
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else:
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f.append(obj)
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return t, f
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def drange(v0: float, v1: float, d: int) -> range:
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"""Returns a discrete range."""
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return range(int(v0) // d, int(v1 + d) // d)
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def get_bound(pts: Iterable[Point]) -> Rect:
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"""Compute a minimal rectangle that covers all the points."""
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limit: Rect = (INF, INF, -INF, -INF)
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(x0, y0, x1, y1) = limit
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for (x, y) in pts:
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x0 = min(x0, x)
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y0 = min(y0, y)
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x1 = max(x1, x)
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y1 = max(y1, y)
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return x0, y0, x1, y1
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def pick(
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seq: Iterable[_T],
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func: Callable[[_T], float],
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maxobj: Optional[_T] = None
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) -> Optional[_T]:
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"""Picks the object obj where func(obj) has the highest value."""
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maxscore = None
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for obj in seq:
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score = func(obj)
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if maxscore is None or maxscore < score:
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(maxscore, maxobj) = (score, obj)
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return maxobj
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def choplist(n: int, seq: Iterable[_T]) -> Iterator[Tuple[_T, ...]]:
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"""Groups every n elements of the list."""
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r = []
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for x in seq:
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r.append(x)
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if len(r) == n:
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yield tuple(r)
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r = []
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return
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def nunpack(s: bytes, default: int = 0) -> int:
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"""Unpacks 1 to 4 or 8 byte integers (big endian)."""
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length = len(s)
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if not length:
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return default
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elif length == 1:
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return ord(s)
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elif length == 2:
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return cast(int, struct.unpack('>H', s)[0])
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elif length == 3:
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return cast(int, struct.unpack('>L', b'\x00' + s)[0])
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elif length == 4:
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return cast(int, struct.unpack('>L', s)[0])
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elif length == 8:
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return cast(int, struct.unpack('>Q', s)[0])
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else:
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raise TypeError('invalid length: %d' % length)
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PDFDocEncoding = ''.join(chr(x) for x in (
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0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,
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0x0008, 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f,
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0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0017, 0x0017,
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0x02d8, 0x02c7, 0x02c6, 0x02d9, 0x02dd, 0x02db, 0x02da, 0x02dc,
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0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
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0x0028, 0x0029, 0x002a, 0x002b, 0x002c, 0x002d, 0x002e, 0x002f,
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0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
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0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e, 0x003f,
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0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
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0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f,
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0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
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0x0058, 0x0059, 0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f,
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0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
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0x0068, 0x0069, 0x006a, 0x006b, 0x006c, 0x006d, 0x006e, 0x006f,
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0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
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0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d, 0x007e, 0x0000,
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0x2022, 0x2020, 0x2021, 0x2026, 0x2014, 0x2013, 0x0192, 0x2044,
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0x2039, 0x203a, 0x2212, 0x2030, 0x201e, 0x201c, 0x201d, 0x2018,
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0x2019, 0x201a, 0x2122, 0xfb01, 0xfb02, 0x0141, 0x0152, 0x0160,
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0x0178, 0x017d, 0x0131, 0x0142, 0x0153, 0x0161, 0x017e, 0x0000,
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0x20ac, 0x00a1, 0x00a2, 0x00a3, 0x00a4, 0x00a5, 0x00a6, 0x00a7,
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0x00a8, 0x00a9, 0x00aa, 0x00ab, 0x00ac, 0x0000, 0x00ae, 0x00af,
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0x00b0, 0x00b1, 0x00b2, 0x00b3, 0x00b4, 0x00b5, 0x00b6, 0x00b7,
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0x00b8, 0x00b9, 0x00ba, 0x00bb, 0x00bc, 0x00bd, 0x00be, 0x00bf,
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0x00c0, 0x00c1, 0x00c2, 0x00c3, 0x00c4, 0x00c5, 0x00c6, 0x00c7,
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0x00c8, 0x00c9, 0x00ca, 0x00cb, 0x00cc, 0x00cd, 0x00ce, 0x00cf,
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0x00d0, 0x00d1, 0x00d2, 0x00d3, 0x00d4, 0x00d5, 0x00d6, 0x00d7,
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0x00d8, 0x00d9, 0x00da, 0x00db, 0x00dc, 0x00dd, 0x00de, 0x00df,
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0x00e0, 0x00e1, 0x00e2, 0x00e3, 0x00e4, 0x00e5, 0x00e6, 0x00e7,
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0x00e8, 0x00e9, 0x00ea, 0x00eb, 0x00ec, 0x00ed, 0x00ee, 0x00ef,
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0x00f0, 0x00f1, 0x00f2, 0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7,
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0x00f8, 0x00f9, 0x00fa, 0x00fb, 0x00fc, 0x00fd, 0x00fe, 0x00ff,
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))
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def decode_text(s: bytes) -> str:
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"""Decodes a PDFDocEncoding string to Unicode."""
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if s.startswith(b'\xfe\xff'):
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return str(s[2:], 'utf-16be', 'ignore')
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else:
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return ''.join(PDFDocEncoding[c] for c in s)
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def enc(x: str) -> str:
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"""Encodes a string for SGML/XML/HTML"""
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if isinstance(x, bytes):
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return ''
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return escape(x)
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def bbox2str(bbox: Rect) -> str:
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(x0, y0, x1, y1) = bbox
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return '{:.3f},{:.3f},{:.3f},{:.3f}'.format(x0, y0, x1, y1)
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def matrix2str(m: Matrix) -> str:
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(a, b, c, d, e, f) = m
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return '[{:.2f},{:.2f},{:.2f},{:.2f}, ({:.2f},{:.2f})]'\
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.format(a, b, c, d, e, f)
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def vecBetweenBoxes(obj1: "LTComponent", obj2: "LTComponent") -> Point:
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"""A distance function between two TextBoxes.
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Consider the bounding rectangle for obj1 and obj2.
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Return vector between 2 boxes boundaries if they don't overlap, otherwise
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returns vector betweeen boxes centers
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+------+..........+ (x1, y1)
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| obj1 | :
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+------+www+------+
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: | obj2 |
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(x0, y0) +..........+------+
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"""
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(x0, y0) = (min(obj1.x0, obj2.x0), min(obj1.y0, obj2.y0))
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(x1, y1) = (max(obj1.x1, obj2.x1), max(obj1.y1, obj2.y1))
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(ow, oh) = (x1 - x0, y1 - y0)
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(iw, ih) = (ow - obj1.width - obj2.width, oh - obj1.height - obj2.height)
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if iw < 0 and ih < 0:
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# if one is inside another we compute euclidean distance
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(xc1, yc1) = ((obj1.x0 + obj1.x1) / 2, (obj1.y0 + obj1.y1) / 2)
|
|
(xc2, yc2) = ((obj2.x0 + obj2.x1) / 2, (obj2.y0 + obj2.y1) / 2)
|
|
return xc1 - xc2, yc1 - yc2
|
|
else:
|
|
return max(0, iw), max(0, ih)
|
|
|
|
|
|
LTComponentT = TypeVar('LTComponentT', bound='LTComponent')
|
|
|
|
|
|
class Plane(Generic[LTComponentT]):
|
|
"""A set-like data structure for objects placed on a plane.
|
|
|
|
Can efficiently find objects in a certain rectangular area.
|
|
It maintains two parallel lists of objects, each of
|
|
which is sorted by its x or y coordinate.
|
|
"""
|
|
|
|
def __init__(self, bbox: Rect, gridsize: int = 50) -> None:
|
|
self._seq: List[LTComponentT] = [] # preserve the object order.
|
|
self._objs: Set[LTComponentT] = set()
|
|
self._grid: Dict[Point, List[LTComponentT]] = {}
|
|
self.gridsize = gridsize
|
|
(self.x0, self.y0, self.x1, self.y1) = bbox
|
|
|
|
def __repr__(self) -> str:
|
|
return '<Plane objs=%r>' % list(self)
|
|
|
|
def __iter__(self) -> Iterator[LTComponentT]:
|
|
return (obj for obj in self._seq if obj in self._objs)
|
|
|
|
def __len__(self) -> int:
|
|
return len(self._objs)
|
|
|
|
def __contains__(self, obj: object) -> bool:
|
|
return obj in self._objs
|
|
|
|
def _getrange(self, bbox: Rect) -> Iterator[Point]:
|
|
(x0, y0, x1, y1) = bbox
|
|
if x1 <= self.x0 or self.x1 <= x0 or y1 <= self.y0 or self.y1 <= y0:
|
|
return
|
|
x0 = max(self.x0, x0)
|
|
y0 = max(self.y0, y0)
|
|
x1 = min(self.x1, x1)
|
|
y1 = min(self.y1, y1)
|
|
for grid_y in drange(y0, y1, self.gridsize):
|
|
for grid_x in drange(x0, x1, self.gridsize):
|
|
yield (grid_x, grid_y)
|
|
|
|
def extend(self, objs: Iterable[LTComponentT]) -> None:
|
|
for obj in objs:
|
|
self.add(obj)
|
|
|
|
def add(self, obj: LTComponentT) -> None:
|
|
"""place an object."""
|
|
for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
|
|
if k not in self._grid:
|
|
r: List[LTComponentT] = []
|
|
self._grid[k] = r
|
|
else:
|
|
r = self._grid[k]
|
|
r.append(obj)
|
|
self._seq.append(obj)
|
|
self._objs.add(obj)
|
|
|
|
def remove(self, obj: LTComponentT) -> None:
|
|
"""displace an object."""
|
|
for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
|
|
try:
|
|
self._grid[k].remove(obj)
|
|
except (KeyError, ValueError):
|
|
pass
|
|
self._objs.remove(obj)
|
|
|
|
def find(self, bbox: Rect) -> Iterator[LTComponentT]:
|
|
"""finds objects that are in a certain area."""
|
|
(x0, y0, x1, y1) = bbox
|
|
done = set()
|
|
for k in self._getrange(bbox):
|
|
if k not in self._grid:
|
|
continue
|
|
for obj in self._grid[k]:
|
|
if obj in done:
|
|
continue
|
|
done.add(obj)
|
|
if obj.x1 <= x0 or x1 <= obj.x0 or obj.y1 <= y0 \
|
|
or y1 <= obj.y0:
|
|
continue
|
|
yield obj
|