tcl.gd doesn't properly detect if gd has jpeg/png/gif support in linux/docker

[zeroschism]

hammu tcl.gd % GD create_from_jpeg
GD library not built with JPEG support
while evaluating GD create_from_jpeg
hammu tcl.gd % GD create_from_gif
GD library not built with GIF support
while evaluating GD create_from_gif
hammu tcl.gd % GD create_from_png
GD library not built with PNG support
while evaluating GD create_from_png

yet:

# dpkg --list | egrep "(png|jpeg|gif)"
ii  libgif-dev                             5.1.4-2ubuntu0.1                  amd64        library for GIF images (development)
ii  libgif7:amd64                          5.1.4-2ubuntu0.1                  amd64        library for GIF images (library)
ii  libjpeg-dev:amd64                      8c-2ubuntu8                       amd64        Independent JPEG Group's JPEG runtime library (dependency package)
ii  libjpeg-turbo8:amd64                   1.5.2-0ubuntu5.18.04.3            amd64        IJG JPEG compliant runtime library.
ii  libjpeg-turbo8-dev:amd64               1.5.2-0ubuntu5.18.04.3            amd64        Development files for the IJG JPEG library
ii  libjpeg8:amd64                         8c-2ubuntu8                       amd64        Independent JPEG Group's JPEG runtime library (dependency package)
ii  libjpeg8-dev:amd64                     8c-2ubuntu8                       amd64        Independent JPEG Group's JPEG runtime library (dependency package)
ii  libpng-dev:amd64                       1.6.34-1ubuntu0.18.04.2           amd64        PNG library - development (version 1.6)
ii  libpng-tools                           1.6.34-1ubuntu0.18.04.2           amd64        PNG library - tools (version 1.6)
ii  libpng16-16:amd64                      1.6.34-1ubuntu0.18.04.2           amd64        PNG library - runtime (version 1.6)```

[bovine]

It uses libgd, not any of those libraries.

Check the contents of the installed gd.h to see if it references GD_GIF, GD_PNG, or GD_JPEG

[snoe925]

This appears related to the deprecation of gdlib-config and the wrapper script placed in this repository. The pkg-config mechanism is not working right. It think the names of the defines might need be the standard GD_PNG -> HAVE_LIBPNG. In the generic/tclgd.c

[snoe925]

The png-config actually does nothing as CFLAGS is empty. In either case I would expect a modern define to be HAVE_LIBPNG instead of GD_PNG.

# pkg-config --modversion gdlib
2.2.5
# pkg-config --cflags gdlib
#

[gromgit]

It uses libgd, not any of those libraries.

That's only true for GIF, and it's always included, so the #ifndef GD_GIF tests in generic/tclgd.c are defunct.

[gromgit]

As for the other file formats, upstream has declared in libgd/libgd#345 that all format-specific functions will at least be stubbed for linking purpose, so the official feature detection method is to call gdSupportsFileType at runtime.