pdf2zh/ccitt.py

# CCITT Fax decoder
#
# Bugs: uncompressed mode untested.
#
# cf.
#  ITU-T Recommendation T.4
#    "Standardization of Group 3 facsimile terminals
#    for document transmission"
#  ITU-T Recommendation T.6
#    "FACSIMILE CODING SCHEMES AND CODING CONTROL FUNCTIONS
#    FOR GROUP 4 FACSIMILE APPARATUS"


import array
from typing import (
    Any,
    Callable,
    Dict,
    Iterator,
    List,
    MutableSequence,
    Optional,
    Sequence,
    Union,
    cast,
)

from pdf2zh.pdfexceptions import PDFException, PDFValueError


def get_bytes(data: bytes) -> Iterator[int]:
    yield from data


# Workaround https://github.com/python/mypy/issues/731
BitParserState = MutableSequence[Any]
# A better definition (not supported by mypy) would be:
# BitParserState = MutableSequence[Union["BitParserState", int, str, None]]


class BitParser:
    _state: BitParserState

    # _accept is declared Optional solely as a workaround for
    # https://github.com/python/mypy/issues/708
    _accept: Optional[Callable[[Any], BitParserState]]

    def __init__(self) -> None:
        self._pos = 0

    @classmethod
    def add(cls, root: BitParserState, v: Union[int, str], bits: str) -> None:
        p: BitParserState = root
        b = None
        for i in range(len(bits)):
            if i > 0:
                assert b is not None
                if p[b] is None:
                    p[b] = [None, None]
                p = p[b]
            if bits[i] == "1":
                b = 1
            else:
                b = 0
        assert b is not None
        p[b] = v

    def feedbytes(self, data: bytes) -> None:
        for byte in get_bytes(data):
            for m in (128, 64, 32, 16, 8, 4, 2, 1):
                self._parse_bit(byte & m)

    def _parse_bit(self, x: object) -> None:
        if x:
            v = self._state[1]
        else:
            v = self._state[0]
        self._pos += 1
        if isinstance(v, list):
            self._state = v
        else:
            assert self._accept is not None
            self._state = self._accept(v)


class CCITTG4Parser(BitParser):
    MODE = [None, None]
    BitParser.add(MODE, 0, "1")
    BitParser.add(MODE, +1, "011")
    BitParser.add(MODE, -1, "010")
    BitParser.add(MODE, "h", "001")
    BitParser.add(MODE, "p", "0001")
    BitParser.add(MODE, +2, "000011")
    BitParser.add(MODE, -2, "000010")
    BitParser.add(MODE, +3, "0000011")
    BitParser.add(MODE, -3, "0000010")
    BitParser.add(MODE, "u", "0000001111")
    BitParser.add(MODE, "x1", "0000001000")
    BitParser.add(MODE, "x2", "0000001001")
    BitParser.add(MODE, "x3", "0000001010")
    BitParser.add(MODE, "x4", "0000001011")
    BitParser.add(MODE, "x5", "0000001100")
    BitParser.add(MODE, "x6", "0000001101")
    BitParser.add(MODE, "x7", "0000001110")
    BitParser.add(MODE, "e", "000000000001000000000001")

    WHITE = [None, None]
    BitParser.add(WHITE, 0, "00110101")
    BitParser.add(WHITE, 1, "000111")
    BitParser.add(WHITE, 2, "0111")
    BitParser.add(WHITE, 3, "1000")
    BitParser.add(WHITE, 4, "1011")
    BitParser.add(WHITE, 5, "1100")
    BitParser.add(WHITE, 6, "1110")
    BitParser.add(WHITE, 7, "1111")
    BitParser.add(WHITE, 8, "10011")
    BitParser.add(WHITE, 9, "10100")
    BitParser.add(WHITE, 10, "00111")
    BitParser.add(WHITE, 11, "01000")
    BitParser.add(WHITE, 12, "001000")
    BitParser.add(WHITE, 13, "000011")
    BitParser.add(WHITE, 14, "110100")
    BitParser.add(WHITE, 15, "110101")
    BitParser.add(WHITE, 16, "101010")
    BitParser.add(WHITE, 17, "101011")
    BitParser.add(WHITE, 18, "0100111")
    BitParser.add(WHITE, 19, "0001100")
    BitParser.add(WHITE, 20, "0001000")
    BitParser.add(WHITE, 21, "0010111")
    BitParser.add(WHITE, 22, "0000011")
    BitParser.add(WHITE, 23, "0000100")
    BitParser.add(WHITE, 24, "0101000")
    BitParser.add(WHITE, 25, "0101011")
    BitParser.add(WHITE, 26, "0010011")
    BitParser.add(WHITE, 27, "0100100")
    BitParser.add(WHITE, 28, "0011000")
    BitParser.add(WHITE, 29, "00000010")
    BitParser.add(WHITE, 30, "00000011")
    BitParser.add(WHITE, 31, "00011010")
    BitParser.add(WHITE, 32, "00011011")
    BitParser.add(WHITE, 33, "00010010")
    BitParser.add(WHITE, 34, "00010011")
    BitParser.add(WHITE, 35, "00010100")
    BitParser.add(WHITE, 36, "00010101")
    BitParser.add(WHITE, 37, "00010110")
    BitParser.add(WHITE, 38, "00010111")
    BitParser.add(WHITE, 39, "00101000")
    BitParser.add(WHITE, 40, "00101001")
    BitParser.add(WHITE, 41, "00101010")
    BitParser.add(WHITE, 42, "00101011")
    BitParser.add(WHITE, 43, "00101100")
    BitParser.add(WHITE, 44, "00101101")
    BitParser.add(WHITE, 45, "00000100")
    BitParser.add(WHITE, 46, "00000101")
    BitParser.add(WHITE, 47, "00001010")
    BitParser.add(WHITE, 48, "00001011")
    BitParser.add(WHITE, 49, "01010010")
    BitParser.add(WHITE, 50, "01010011")
    BitParser.add(WHITE, 51, "01010100")
    BitParser.add(WHITE, 52, "01010101")
    BitParser.add(WHITE, 53, "00100100")
    BitParser.add(WHITE, 54, "00100101")
    BitParser.add(WHITE, 55, "01011000")
    BitParser.add(WHITE, 56, "01011001")
    BitParser.add(WHITE, 57, "01011010")
    BitParser.add(WHITE, 58, "01011011")
    BitParser.add(WHITE, 59, "01001010")
    BitParser.add(WHITE, 60, "01001011")
    BitParser.add(WHITE, 61, "00110010")
    BitParser.add(WHITE, 62, "00110011")
    BitParser.add(WHITE, 63, "00110100")
    BitParser.add(WHITE, 64, "11011")
    BitParser.add(WHITE, 128, "10010")
    BitParser.add(WHITE, 192, "010111")
    BitParser.add(WHITE, 256, "0110111")
    BitParser.add(WHITE, 320, "00110110")
    BitParser.add(WHITE, 384, "00110111")
    BitParser.add(WHITE, 448, "01100100")
    BitParser.add(WHITE, 512, "01100101")
    BitParser.add(WHITE, 576, "01101000")
    BitParser.add(WHITE, 640, "01100111")
    BitParser.add(WHITE, 704, "011001100")
    BitParser.add(WHITE, 768, "011001101")
    BitParser.add(WHITE, 832, "011010010")
    BitParser.add(WHITE, 896, "011010011")
    BitParser.add(WHITE, 960, "011010100")
    BitParser.add(WHITE, 1024, "011010101")
    BitParser.add(WHITE, 1088, "011010110")
    BitParser.add(WHITE, 1152, "011010111")
    BitParser.add(WHITE, 1216, "011011000")
    BitParser.add(WHITE, 1280, "011011001")
    BitParser.add(WHITE, 1344, "011011010")
    BitParser.add(WHITE, 1408, "011011011")
    BitParser.add(WHITE, 1472, "010011000")
    BitParser.add(WHITE, 1536, "010011001")
    BitParser.add(WHITE, 1600, "010011010")
    BitParser.add(WHITE, 1664, "011000")
    BitParser.add(WHITE, 1728, "010011011")
    BitParser.add(WHITE, 1792, "00000001000")
    BitParser.add(WHITE, 1856, "00000001100")
    BitParser.add(WHITE, 1920, "00000001101")
    BitParser.add(WHITE, 1984, "000000010010")
    BitParser.add(WHITE, 2048, "000000010011")
    BitParser.add(WHITE, 2112, "000000010100")
    BitParser.add(WHITE, 2176, "000000010101")
    BitParser.add(WHITE, 2240, "000000010110")
    BitParser.add(WHITE, 2304, "000000010111")
    BitParser.add(WHITE, 2368, "000000011100")
    BitParser.add(WHITE, 2432, "000000011101")
    BitParser.add(WHITE, 2496, "000000011110")
    BitParser.add(WHITE, 2560, "000000011111")

    BLACK = [None, None]
    BitParser.add(BLACK, 0, "0000110111")
    BitParser.add(BLACK, 1, "010")
    BitParser.add(BLACK, 2, "11")
    BitParser.add(BLACK, 3, "10")
    BitParser.add(BLACK, 4, "011")
    BitParser.add(BLACK, 5, "0011")
    BitParser.add(BLACK, 6, "0010")
    BitParser.add(BLACK, 7, "00011")
    BitParser.add(BLACK, 8, "000101")
    BitParser.add(BLACK, 9, "000100")
    BitParser.add(BLACK, 10, "0000100")
    BitParser.add(BLACK, 11, "0000101")
    BitParser.add(BLACK, 12, "0000111")
    BitParser.add(BLACK, 13, "00000100")
    BitParser.add(BLACK, 14, "00000111")
    BitParser.add(BLACK, 15, "000011000")
    BitParser.add(BLACK, 16, "0000010111")
    BitParser.add(BLACK, 17, "0000011000")
    BitParser.add(BLACK, 18, "0000001000")
    BitParser.add(BLACK, 19, "00001100111")
    BitParser.add(BLACK, 20, "00001101000")
    BitParser.add(BLACK, 21, "00001101100")
    BitParser.add(BLACK, 22, "00000110111")
    BitParser.add(BLACK, 23, "00000101000")
    BitParser.add(BLACK, 24, "00000010111")
    BitParser.add(BLACK, 25, "00000011000")
    BitParser.add(BLACK, 26, "000011001010")
    BitParser.add(BLACK, 27, "000011001011")
    BitParser.add(BLACK, 28, "000011001100")
    BitParser.add(BLACK, 29, "000011001101")
    BitParser.add(BLACK, 30, "000001101000")
    BitParser.add(BLACK, 31, "000001101001")
    BitParser.add(BLACK, 32, "000001101010")
    BitParser.add(BLACK, 33, "000001101011")
    BitParser.add(BLACK, 34, "000011010010")
    BitParser.add(BLACK, 35, "000011010011")
    BitParser.add(BLACK, 36, "000011010100")
    BitParser.add(BLACK, 37, "000011010101")
    BitParser.add(BLACK, 38, "000011010110")
    BitParser.add(BLACK, 39, "000011010111")
    BitParser.add(BLACK, 40, "000001101100")
    BitParser.add(BLACK, 41, "000001101101")
    BitParser.add(BLACK, 42, "000011011010")
    BitParser.add(BLACK, 43, "000011011011")
    BitParser.add(BLACK, 44, "000001010100")
    BitParser.add(BLACK, 45, "000001010101")
    BitParser.add(BLACK, 46, "000001010110")
    BitParser.add(BLACK, 47, "000001010111")
    BitParser.add(BLACK, 48, "000001100100")
    BitParser.add(BLACK, 49, "000001100101")
    BitParser.add(BLACK, 50, "000001010010")
    BitParser.add(BLACK, 51, "000001010011")
    BitParser.add(BLACK, 52, "000000100100")
    BitParser.add(BLACK, 53, "000000110111")
    BitParser.add(BLACK, 54, "000000111000")
    BitParser.add(BLACK, 55, "000000100111")
    BitParser.add(BLACK, 56, "000000101000")
    BitParser.add(BLACK, 57, "000001011000")
    BitParser.add(BLACK, 58, "000001011001")
    BitParser.add(BLACK, 59, "000000101011")
    BitParser.add(BLACK, 60, "000000101100")
    BitParser.add(BLACK, 61, "000001011010")
    BitParser.add(BLACK, 62, "000001100110")
    BitParser.add(BLACK, 63, "000001100111")
    BitParser.add(BLACK, 64, "0000001111")
    BitParser.add(BLACK, 128, "000011001000")
    BitParser.add(BLACK, 192, "000011001001")
    BitParser.add(BLACK, 256, "000001011011")
    BitParser.add(BLACK, 320, "000000110011")
    BitParser.add(BLACK, 384, "000000110100")
    BitParser.add(BLACK, 448, "000000110101")
    BitParser.add(BLACK, 512, "0000001101100")
    BitParser.add(BLACK, 576, "0000001101101")
    BitParser.add(BLACK, 640, "0000001001010")
    BitParser.add(BLACK, 704, "0000001001011")
    BitParser.add(BLACK, 768, "0000001001100")
    BitParser.add(BLACK, 832, "0000001001101")
    BitParser.add(BLACK, 896, "0000001110010")
    BitParser.add(BLACK, 960, "0000001110011")
    BitParser.add(BLACK, 1024, "0000001110100")
    BitParser.add(BLACK, 1088, "0000001110101")
    BitParser.add(BLACK, 1152, "0000001110110")
    BitParser.add(BLACK, 1216, "0000001110111")
    BitParser.add(BLACK, 1280, "0000001010010")
    BitParser.add(BLACK, 1344, "0000001010011")
    BitParser.add(BLACK, 1408, "0000001010100")
    BitParser.add(BLACK, 1472, "0000001010101")
    BitParser.add(BLACK, 1536, "0000001011010")
    BitParser.add(BLACK, 1600, "0000001011011")
    BitParser.add(BLACK, 1664, "0000001100100")
    BitParser.add(BLACK, 1728, "0000001100101")
    BitParser.add(BLACK, 1792, "00000001000")
    BitParser.add(BLACK, 1856, "00000001100")
    BitParser.add(BLACK, 1920, "00000001101")
    BitParser.add(BLACK, 1984, "000000010010")
    BitParser.add(BLACK, 2048, "000000010011")
    BitParser.add(BLACK, 2112, "000000010100")
    BitParser.add(BLACK, 2176, "000000010101")
    BitParser.add(BLACK, 2240, "000000010110")
    BitParser.add(BLACK, 2304, "000000010111")
    BitParser.add(BLACK, 2368, "000000011100")
    BitParser.add(BLACK, 2432, "000000011101")
    BitParser.add(BLACK, 2496, "000000011110")
    BitParser.add(BLACK, 2560, "000000011111")

    UNCOMPRESSED = [None, None]
    BitParser.add(UNCOMPRESSED, "1", "1")
    BitParser.add(UNCOMPRESSED, "01", "01")
    BitParser.add(UNCOMPRESSED, "001", "001")
    BitParser.add(UNCOMPRESSED, "0001", "0001")
    BitParser.add(UNCOMPRESSED, "00001", "00001")
    BitParser.add(UNCOMPRESSED, "00000", "000001")
    BitParser.add(UNCOMPRESSED, "T00", "00000011")
    BitParser.add(UNCOMPRESSED, "T10", "00000010")
    BitParser.add(UNCOMPRESSED, "T000", "000000011")
    BitParser.add(UNCOMPRESSED, "T100", "000000010")
    BitParser.add(UNCOMPRESSED, "T0000", "0000000011")
    BitParser.add(UNCOMPRESSED, "T1000", "0000000010")
    BitParser.add(UNCOMPRESSED, "T00000", "00000000011")
    BitParser.add(UNCOMPRESSED, "T10000", "00000000010")

    class CCITTException(PDFException):
        pass

    class EOFB(CCITTException):
        pass

    class InvalidData(CCITTException):
        pass

    class ByteSkip(CCITTException):
        pass

    _color: int

    def __init__(self, width: int, bytealign: bool = False) -> None:
        BitParser.__init__(self)
        self.width = width
        self.bytealign = bytealign
        self.reset()

    def feedbytes(self, data: bytes) -> None:
        for byte in get_bytes(data):
            try:
                for m in (128, 64, 32, 16, 8, 4, 2, 1):
                    self._parse_bit(byte & m)
            except self.ByteSkip:
                self._accept = self._parse_mode
                self._state = self.MODE
            except self.EOFB:
                break

    def _parse_mode(self, mode: object) -> BitParserState:
        if mode == "p":
            self._do_pass()
            self._flush_line()
            return self.MODE
        elif mode == "h":
            self._n1 = 0
            self._accept = self._parse_horiz1
            if self._color:
                return self.WHITE
            else:
                return self.BLACK
        elif mode == "u":
            self._accept = self._parse_uncompressed
            return self.UNCOMPRESSED
        elif mode == "e":
            raise self.EOFB
        elif isinstance(mode, int):
            self._do_vertical(mode)
            self._flush_line()
            return self.MODE
        else:
            raise self.InvalidData(mode)

    def _parse_horiz1(self, n: Any) -> BitParserState:
        if n is None:
            raise self.InvalidData
        self._n1 += n
        if n < 64:
            self._n2 = 0
            self._color = 1 - self._color
            self._accept = self._parse_horiz2
        if self._color:
            return self.WHITE
        else:
            return self.BLACK

    def _parse_horiz2(self, n: Any) -> BitParserState:
        if n is None:
            raise self.InvalidData
        self._n2 += n
        if n < 64:
            self._color = 1 - self._color
            self._accept = self._parse_mode
            self._do_horizontal(self._n1, self._n2)
            self._flush_line()
            return self.MODE
        elif self._color:
            return self.WHITE
        else:
            return self.BLACK

    def _parse_uncompressed(self, bits: Optional[str]) -> BitParserState:
        if not bits:
            raise self.InvalidData
        if bits.startswith("T"):
            self._accept = self._parse_mode
            self._color = int(bits[1])
            self._do_uncompressed(bits[2:])
            return self.MODE
        else:
            self._do_uncompressed(bits)
            return self.UNCOMPRESSED

    def _get_bits(self) -> str:
        return "".join(str(b) for b in self._curline[: self._curpos])

    def _get_refline(self, i: int) -> str:
        if i < 0:
            return "[]" + "".join(str(b) for b in self._refline)
        elif len(self._refline) <= i:
            return "".join(str(b) for b in self._refline) + "[]"
        else:
            return (
                "".join(str(b) for b in self._refline[:i])
                + "["
                + str(self._refline[i])
                + "]"
                + "".join(str(b) for b in self._refline[i + 1 :])
            )

    def reset(self) -> None:
        self._y = 0
        self._curline = array.array("b", [1] * self.width)
        self._reset_line()
        self._accept = self._parse_mode
        self._state = self.MODE

    def output_line(self, y: int, bits: Sequence[int]) -> None:
        print(y, "".join(str(b) for b in bits))

    def _reset_line(self) -> None:
        self._refline = self._curline
        self._curline = array.array("b", [1] * self.width)
        self._curpos = -1
        self._color = 1

    def _flush_line(self) -> None:
        if self.width <= self._curpos:
            self.output_line(self._y, self._curline)
            self._y += 1
            self._reset_line()
            if self.bytealign:
                raise self.ByteSkip

    def _do_vertical(self, dx: int) -> None:
        x1 = self._curpos + 1
        while 1:
            if x1 == 0:
                if self._color == 1 and self._refline[x1] != self._color:
                    break
            elif x1 == len(self._refline) or (
                self._refline[x1 - 1] == self._color
                and self._refline[x1] != self._color
            ):
                break
            x1 += 1
        x1 += dx
        x0 = max(0, self._curpos)
        x1 = max(0, min(self.width, x1))
        if x1 < x0:
            for x in range(x1, x0):
                self._curline[x] = self._color
        elif x0 < x1:
            for x in range(x0, x1):
                self._curline[x] = self._color
        self._curpos = x1
        self._color = 1 - self._color

    def _do_pass(self) -> None:
        x1 = self._curpos + 1
        while 1:
            if x1 == 0:
                if self._color == 1 and self._refline[x1] != self._color:
                    break
            elif x1 == len(self._refline) or (
                self._refline[x1 - 1] == self._color
                and self._refline[x1] != self._color
            ):
                break
            x1 += 1
        while 1:
            if x1 == 0:
                if self._color == 0 and self._refline[x1] == self._color:
                    break
            elif x1 == len(self._refline) or (
                self._refline[x1 - 1] != self._color
                and self._refline[x1] == self._color
            ):
                break
            x1 += 1
        for x in range(self._curpos, x1):
            self._curline[x] = self._color
        self._curpos = x1

    def _do_horizontal(self, n1: int, n2: int) -> None:
        if self._curpos < 0:
            self._curpos = 0
        x = self._curpos
        for _ in range(n1):
            if len(self._curline) <= x:
                break
            self._curline[x] = self._color
            x += 1
        for _ in range(n2):
            if len(self._curline) <= x:
                break
            self._curline[x] = 1 - self._color
            x += 1
        self._curpos = x

    def _do_uncompressed(self, bits: str) -> None:
        for c in bits:
            self._curline[self._curpos] = int(c)
            self._curpos += 1
            self._flush_line()


class CCITTFaxDecoder(CCITTG4Parser):
    def __init__(
        self,
        width: int,
        bytealign: bool = False,
        reversed: bool = False,
    ) -> None:
        CCITTG4Parser.__init__(self, width, bytealign=bytealign)
        self.reversed = reversed
        self._buf = b""

    def close(self) -> bytes:
        return self._buf

    def output_line(self, y: int, bits: Sequence[int]) -> None:
        arr = array.array("B", [0] * ((len(bits) + 7) // 8))
        if self.reversed:
            bits = [1 - b for b in bits]
        for i, b in enumerate(bits):
            if b:
                arr[i // 8] += (128, 64, 32, 16, 8, 4, 2, 1)[i % 8]
        self._buf += arr.tobytes()


def ccittfaxdecode(data: bytes, params: Dict[str, object]) -> bytes:
    K = params.get("K")
    if K == -1:
        cols = cast(int, params.get("Columns"))
        bytealign = cast(bool, params.get("EncodedByteAlign"))
        reversed = cast(bool, params.get("BlackIs1"))
        parser = CCITTFaxDecoder(cols, bytealign=bytealign, reversed=reversed)
    else:
        raise PDFValueError(K)
    parser.feedbytes(data)
    return parser.close()


# test
def main(argv: List[str]) -> None:
    if not argv[1:]:
        import unittest

        unittest.main()
        return

    class Parser(CCITTG4Parser):
        def __init__(self, width: int, bytealign: bool = False) -> None:
            import pygame  # type: ignore[import]

            CCITTG4Parser.__init__(self, width, bytealign=bytealign)
            self.img = pygame.Surface((self.width, 1000))

        def output_line(self, y: int, bits: Sequence[int]) -> None:
            for x, b in enumerate(bits):
                if b:
                    self.img.set_at((x, y), (255, 255, 255))
                else:
                    self.img.set_at((x, y), (0, 0, 0))

        def close(self) -> None:
            import pygame

            pygame.image.save(self.img, "out.bmp")

    for path in argv[1:]:
        fp = open(path, "rb")
        (_, _, k, w, h, _) = path.split(".")
        parser = Parser(int(w))
        parser.feedbytes(fp.read())
        parser.close()
        fp.close()