diff options
| -rw-r--r-- | wcsutil/headerlet.py | 84 |
1 files changed, 58 insertions, 26 deletions
diff --git a/wcsutil/headerlet.py b/wcsutil/headerlet.py index 7b9b454..96dd71a 100644 --- a/wcsutil/headerlet.py +++ b/wcsutil/headerlet.py @@ -673,8 +673,18 @@ class HeaderletHDU(pyfits.core._NonstandardExtHDU): self.__dict__[attr] = self._file.read(size) elif attr == 'headerlet': self._file.seek(self._datLoc) - # TODO: Handle compression - t = tarfile.open(fileobj=self._file) + s = StringIO() + # Read the data into a StringIO--reading directly from the file + # won't work (at least for gzipped files) due to problems deep + # within the gzip module that make it difficult to read gzip files + # embedded in another file + s.write(self._file.read(self.size())) + s.seek(0) + if self._header['COMPRESS']: + mode = 'r:gz' + else: + mode = 'r' + t = tarfile.open(mode=mode, fileobj=s) members = t.getmembers() if not len(members): raise ValueError('The Headerlet contents are missing.') @@ -715,22 +725,8 @@ class HeaderletHDU(pyfits.core._NonstandardExtHDU): phdu = headerlet[0] phduhdr = phdu.header - - cards = [ - pyfits.Card('XTENSION', cls._extension, 'Headerlet extension'), - pyfits.Card('EXTNAME', phdu.header['HDRNAME'], - 'name of the headerlet extension'), - phdu.header.ascard['HDRNAME'], - phdu.header.ascard['DATE'], - pyfits.Card('SIPNAME', headerlet['SIPWCS', 1].header['WCSNAMEA'], - 'SIP distortion model name'), - phdu.header.ascard['NPOLFILE'], - phdu.header.ascard['D2IMFILE'], - pyfits.Card('COMPRESS', compress, 'Uses gzip compression') - ] - hlt_filename = phdu.header['HDRNAME'] + '_hdr.fits' - header = pyfits.Header(pyfits.CardList(cards)) + # TODO: As it stands there's no good way to write out an HDUList in # memory, since it automatically closes the given file-like object when # it's done writing. I'd argue that if passed an open file handler it @@ -752,25 +748,61 @@ class HeaderletHDU(pyfits.core._NonstandardExtHDU): finally: os.remove(name) + cards = [ + pyfits.Card('XTENSION', cls._extension, 'Headerlet extension'), + pyfits.Card('BITPIX', 8, 'array data type'), + pyfits.Card('NAXIS', 1, 'number of array dimensions'), + pyfits.Card('NAXIS1', len(s.getvalue()), 'Axis length'), + pyfits.Card('PCOUNT', 0, 'number of parameters'), + pyfits.Card('GCOUNT', 1, 'number of groups'), + pyfits.Card('EXTNAME', phdu.header['HDRNAME'], + 'name of the headerlet extension'), + phdu.header.ascard['HDRNAME'], + phdu.header.ascard['DATE'], + pyfits.Card('SIPNAME', headerlet['SIPWCS', 1].header['WCSNAMEA'], + 'SIP distortion model name'), + phdu.header.ascard['NPOLFILE'], + phdu.header.ascard['D2IMFILE'], + pyfits.Card('COMPRESS', compress, 'Uses gzip compression') + ] + + header = pyfits.Header(pyfits.CardList(cards)) + hdu = cls(data=pyfits.DELAYED, header=header) hdu._file = s hdu._datLoc = 0 return hdu - def size(self): + @classmethod + def match_header(cls, header): """ - Returns the size of the HDU's data portion. + This is a class method used in the pyfits refactoring branch to + recognize whether or not this class should be used for instantiating + an HDU object based on values in the header. + + It is included here for forward-compatibility. """ - self._file.seek(self._datLoc) - t = tarfile.open(fileobj=self._file) - # This will seek to the end of the tarfile - t.getmembers() - return self._file.tell() - self._datLoc + card = header.ascard[0] + if card.key != 'XTENSION': + return False + xtension = card.value.rstrip() + return xtension == cls._extension # TODO: Add header verification def _summary(self): # TODO: Perhaps make this more descriptive... - return '%-6s %-10s %3d' % (self.name, self.__class__.__name__, - len(self._header.ascard)) + return '%-10s %-12s %4d' % (self.name, self.__class__.__name__, + len(self._header.ascard)) + +# Monkey-patch pyfits to add minimal support for HeaderletHDUs +# TODO: Get rid of this ASAP!!! (it won't be necessary with the pyfits +# refactoring branch) +__old_updateHDUtype = pyfits.Header._updateHDUtype +def __updateHDUtype(self): + if HeaderletHDU.match_header(self): + self._hdutype = HeaderletHDU + else: + __old_updateHDUtype(self) +pyfits.Header._updateHDUtype = __updateHDUtype |