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2005.03.22 18:58 "Re: Interface to query compression/subformat parameters", by Frank Warmerdam
On Tue, 22 Mar 2005 12:45:03 -0600 (CST), Bob Friesenhahn wrote:
> Libtiff does not appear to provide a way by which the dependent
> application may determine the supported TIFF encoding formats,
> parameters supported by those encoding formats. It also does not
> appear to provide a way to determine the available compression
> options. For example, I don't see a way to see if LZW compression is
> supported by libtiff.
>
> The ability to query for this information should be added so that
> libtiff becomes easier to use in open-source environments where the
> author of the dependent application is not also responsible for
> providing libtiff.
Bob,
In the not to distant past (perhaps last spring?) Andrey added
the TIFFGetConfiguredCODECS() function to get a list of available
codecs. It doesn't give details of how those codecs are configured
of course. Does it do what you need? I use it like this when I try
to describe to the user what codecs are enabled:
strcpy( szOptionalCompressItems,
" <Value>NONE</Value>" );
#if TIFFLIB_VERSION <= 20040919
strcat( szOptionalCompressItems,
" <Value>PACKBITS</Value>"
" <Value>JPEG</Value>"
" <Value>LZW</Value>"
" <Value>DEFLATE</Value>" );
#else
TIFFCodec *c, *codecs = TIFFGetConfiguredCODECs();
for( c = codecs; c->name; c++ )
{
if( c->scheme == COMPRESSION_PACKBITS )
strcat( szOptionalCompressItems,
" <Value>PACKBITS</Value>" );
else if( c->scheme == COMPRESSION_JPEG )
strcat( szOptionalCompressItems,
" <Value>JPEG</Value>" );
else if( c->scheme == COMPRESSION_LZW )
strcat( szOptionalCompressItems,
" <Value>LZW</Value>" );
else if( c->scheme == COMPRESSION_ADOBE_DEFLATE )
strcat( szOptionalCompressItems,
" <Value>DEFLATE</Value>" );
}
_TIFFfree( codecs );
#endif
--
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent