[GRASS-dev] Is libjpeg actually used?

[Glynn Clements]

Volker Froehlich wrote:

> REQUIREMENTS.html mentions libjpeg as a requirement for Grass,
> specifically for r.out.tiff. The configure script will exit if no
> libjpeg is present.
> 
> On the other hand, the final libraries are not linked to libjpeg and I
> couldn't find a reference in the code.
> 
> Is libjpeg still required?

No, and I'm not sure that it has ever actually been required. In all
probability, the test was a workaround for someone with a version of
libtiff which lacked dependency information. None of the Makefiles or
*.make files use any of JPEGINCPATH, JPEGLIBPATH or JPEGLIB. The last
two are used within configure.in as optional dependencies for libtiff
in the event that the check with -ltiff alone fails.

Everything related to JPEG should be removed from configure.in. The
TIFF check should simply add -ljpeg as an optional dependency, i.e.:

-LOC_CHECK_LIBS(tiff,TIFFOpen,TIFF,$TIFF_LIBRARY_DIRS,TIFFLIB,,,,$JPEGLIBPATH $JPEGLIB,$ZLIB,$MATHLIB)
+LOC_CHECK_LIBS(tiff,TIFFOpen,TIFF,$TIFF_LIBRARY_DIRS,TIFFLIB,,,,-ljpeg,$ZLIB,$MATHLIB)

If additional library directories are required for libjpeg, they can
be added via the --with-tiff-libs= option. Additional header
directories will never be required (the TIFF headers don't include the
JPEG headers).

-- 
Glynn Clements <glynn at gclements.plus.com>