uk.ac.starlink.votable

Class FitsPlusTableWriter

java.lang.Object

uk.ac.starlink.table.StreamStarTableWriter

uk.ac.starlink.fits.AbstractFitsTableWriter

uk.ac.starlink.votable.VOTableFitsTableWriter

uk.ac.starlink.votable.FitsPlusTableWriter

All Implemented Interfaces:

MultiStarTableWriter, StarTableWriter

public class FitsPlusTableWriter
extends VOTableFitsTableWriter

TableWriter which writes table data into the first extension of a FITS file, Unlike FitsTableWriter however, the primary extension is not left contentless, instead it gets the text of a DATA-less VOTable written into it. This VOTable describes the metadata of the table, as if the DATA element contained a FITS element referencing the first extension HDU of the file. Tables stored in this format have all the rich metadata associated with VOTables, and benefit from the compactness of FITS tables, without the considerable disdvantage of being split into two files.

The header cards in the primary HDU look like this:

     SIMPLE  =                    T / Standard FITS format
     BITPIX  =                    8 / Character data
     NAXIS   =                    1 / Text string
     NAXIS1  =                 nnnn / Number of characters
     VOTMETA =                    T / Table metadata in VOTABLE format
     EXTEND  =                    T / There are standard extensions
 

the VOTMETA card in particular marking that this HDU contains VOTable metadata.

Since:

26 Aug 2004

Constructor Summary

Constructors

Constructor and Description
FitsPlusTableWriter() Default constructor.
FitsPlusTableWriter(java.lang.String name, uk.ac.starlink.fits.WideFits wide) Custom constructor.

Method Summary

Modifier and Type	Method and Description
protected uk.ac.starlink.fits.FitsTableSerializer	createSerializer(StarTable table) Provides a suitable serializer for a given table.
protected void	customisePrimaryHeader(nom.tam.fits.Header hdr) Hook for adding custom entries to the FITS header which is written to the primary HDU.
static StarTableWriter[]	getStarTableWriters() Returns a list of FITS-plus table writers with variant values of attributes.
protected boolean	isMagic(int icard, java.lang.String key, java.lang.String value) Tests a header card to see if it looks like part of the magic number for the format written by this handler.
boolean	looksLikeFile(java.lang.String location) Returns true if location ends with something like ".fit" or ".fits".

Methods inherited from class uk.ac.starlink.votable.VOTableFitsTableWriter

isMagic, setVotableVersion, writeStarTables

Methods inherited from class uk.ac.starlink.fits.AbstractFitsTableWriter

addMetadata, getCurrentDate, getFormatName, getMimeType, setFormatName, writePrimaryHDU, writeStarTable, writeStarTables, writeTableHDU

Methods inherited from class uk.ac.starlink.table.StreamStarTableWriter

writeStarTable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface uk.ac.starlink.table.StarTableWriter

writeStarTable

Constructor Detail

FitsPlusTableWriter

public FitsPlusTableWriter()

Default constructor.

FitsPlusTableWriter

public FitsPlusTableWriter(java.lang.String name,
                           uk.ac.starlink.fits.WideFits wide)

Custom constructor.

Parameters:

name - writer name

wide - convention for representing over-wide tables; null to avoid this convention

Method Detail

looksLikeFile

public boolean looksLikeFile(java.lang.String location)

Returns true if location ends with something like ".fit" or ".fits".

Parameters:

location - filename

Returns:

true if it sounds like a fits file

customisePrimaryHeader

protected void customisePrimaryHeader(nom.tam.fits.Header hdr)
                               throws nom.tam.fits.HeaderCardException

Description copied from class: VOTableFitsTableWriter

Hook for adding custom entries to the FITS header which is written to the primary HDU. This is called just after the required cards (SIMPLE, BITPIX, NAXIS, NAXIS1 ) are added and just before the EXTEND card.

Specified by:

customisePrimaryHeader in class VOTableFitsTableWriter

Parameters:

hdr - header

Throws:

nom.tam.fits.HeaderCardException

isMagic

protected boolean isMagic(int icard,
                          java.lang.String key,
                          java.lang.String value)

Description copied from class: VOTableFitsTableWriter

Tests a header card to see if it looks like part of the magic number for the format written by this handler. The VOTableFitsTableWriter implementation tests that the first four cards read:

    SIMPLE = T
    BITPIX = 8
    NAXIS  = 1
    NAXIS1 = ???
 

Subclasses may override this to add tests for later cards (as written in VOTableFitsTableWriter.customisePrimaryHeader(nom.tam.fits.Header)).

Overrides:

isMagic in class VOTableFitsTableWriter

Parameters:

icard - 0-based card index

key - card name

value - card value

Returns:

true iff the presented card is one that could have been written by this writer

createSerializer

protected uk.ac.starlink.fits.FitsTableSerializer createSerializer(StarTable table)
                                                            throws java.io.IOException

Description copied from class: uk.ac.starlink.fits.AbstractFitsTableWriter

Provides a suitable serializer for a given table. Note this should throw an IOException if it can be determined that the submitted table cannot be written by this writer, for instance if it has too many columns.

Specified by:

createSerializer in class uk.ac.starlink.fits.AbstractFitsTableWriter

Parameters:

table - table to serialize

Returns:

FITS serializer

Throws:

java.io.IOException - if the table can't be written

getStarTableWriters

public static StarTableWriter[] getStarTableWriters()

Returns a list of FITS-plus table writers with variant values of attributes. In fact this just returns two functionally identical instances but with different format names: one is "fits" and the other is "fits-plus".

Returns:

table writers