# Source code for PIL.DcxImagePlugin

    #
    # The Python Imaging Library.
    # $Id$
    #
    # DCX file handling
    #
    # DCX is a container file format defined by Intel, commonly used
    # for fax applications.  Each DCX file consists of a directory
    # (a list of file offsets) followed by a set of (usually 1-bit)
    # PCX files.
    #
    # History:
    # 1995-09-09 fl   Created
    # 1996-03-20 fl   Properly derived from PcxImageFile.
    # 1998-07-15 fl   Renamed offset attribute to avoid name clash
    # 2002-07-30 fl   Fixed file handling
    #
    # Copyright (c) 1997-98 by Secret Labs AB.
    # Copyright (c) 1995-96 by Fredrik Lundh.
    #
    # See the README file for information on usage and redistribution.
    #

    from . import Image
    from ._binary import i32le as i32
    from .PcxImagePlugin import PcxImageFile

    MAGIC = 0x3ADE68B1  # QUIZ: what's this value, then?

    def _accept(prefix):
        return len(prefix) >= 4 and i32(prefix) == MAGIC

    ##
    # Image plugin for the Intel DCX format.

    class DcxImageFile(PcxImageFile):

        format = "DCX"
        format_description = "Intel DCX"
        _close_exclusive_fp_after_loading = False

        def _open(self):

            # Header
            s = self.fp.read(4)
            if not _accept(s):
                raise SyntaxError("not a DCX file")

            # Component directory
            self._offset = []
            for i in range(1024):
                offset = i32(self.fp.read(4))
                if not offset:
                    break
                self._offset.append(offset)

            self.__fp = self.fp
            self.frame = None
            self.n_frames = len(self._offset)
            self.is_animated = self.n_frames > 1
            self.seek(0)

        def seek(self, frame):
            if not self._seek_check(frame):
                return
            self.frame = frame
            self.fp = self.__fp
            self.fp.seek(self._offset[frame])
            PcxImageFile._open(self)

        def tell(self):
            return self.frame

        def _close__fp(self):
            try:
                if self.__fp != self.fp:
                    self.__fp.close()
            except AttributeError:
                pass
            finally:
                self.__fp = None

    Image.register_open(DcxImageFile.format, DcxImageFile, _accept)

    Image.register_extension(DcxImageFile.format, ".dcx")