# Source code for PIL.FitsStubImagePlugin

    #
    # The Python Imaging Library
    # $Id$
    #
    # FITS stub adapter
    #
    # Copyright (c) 1998-2003 by Fredrik Lundh
    #
    # See the README file for information on usage and redistribution.
    #

    from . import Image, ImageFile

    _handler = None

    def register_handler(handler):
        """
        Install application-specific FITS image handler.

        :param handler: Handler object.
        """
        global _handler
        _handler = handler

    # --------------------------------------------------------------------
    # Image adapter

    def _accept(prefix):
        return prefix[:6] == b"SIMPLE"

    class FITSStubImageFile(ImageFile.StubImageFile):

        format = "FITS"
        format_description = "FITS"

        def _open(self):
            offset = self.fp.tell()

            headers = {}
            while True:
                header = self.fp.read(80)
                if not header:
                    raise OSError("Truncated FITS file")
                keyword = header[:8].strip()
                if keyword == b"END":
                    break
                value = header[8:].strip()
                if value.startswith(b"="):
                    value = value[1:].strip()
                if not headers and (not _accept(keyword) or value != b"T"):
                    raise SyntaxError("Not a FITS file")
                headers[keyword] = value

            naxis = int(headers[b"NAXIS"])
            if naxis == 0:
                raise ValueError("No image data")
            elif naxis == 1:
                self._size = 1, int(headers[b"NAXIS1"])
            else:
                self._size = int(headers[b"NAXIS1"]), int(headers[b"NAXIS2"])

            number_of_bits = int(headers[b"BITPIX"])
            if number_of_bits == 8:
                self.mode = "L"
            elif number_of_bits == 16:
                self.mode = "I"
                # rawmode = "I;16S"
            elif number_of_bits == 32:
                self.mode = "I"
            elif number_of_bits in (-32, -64):
                self.mode = "F"
                # rawmode = "F" if number_of_bits == -32 else "F;64F"

            self.fp.seek(offset)

            loader = self._load()
            if loader:
                loader.open(self)

        def _load(self):
            return _handler

    def _save(im, fp, filename):
        if _handler is None or not hasattr("_handler", "save"):
            raise OSError("FITS save handler not installed")
        _handler.save(im, fp, filename)

    # --------------------------------------------------------------------
    # Registry

    Image.register_open(FITSStubImageFile.format, FITSStubImageFile, _accept)
    Image.register_save(FITSStubImageFile.format, _save)

    Image.register_extensions(FITSStubImageFile.format, [".fit", ".fits"])