Deployment of images with an info doc

[jemarch]

Hello.

In GNU PDF we are including a lot of pictures in the documentation of
the project (the reference manual, architecture guide, etc).  For each
picture we are including several files: figure.txt for info readers,
figure.png for html output and figure.eps for tex.

In the sources tree the manuals are stored under 'doc/'.  For example:

      doc/gnupdf.texi
      doc/gnupdf-arch.texi
      doc/gnupdf-hg.texi
  
and the pictures (for all the manuals) under 'doc/figures/'.  For
example:

     doc/figures/stream-value-internals.txt
     doc/figures/stream-value-internals.txt
     doc/figures/stream-value-internals.png

The references to the pictures in the texi files are using relative
paths, like in:

@float Figure,fig:stream-value-internals
@image{figures/stream-value-internals}
@caption{Stream value internals}
@end float

"Traditionally" speaking that would be enough, but these days the info
format is supporting the inclusion of png files by including a url to
figure.png along with the ascii version in the .info file.  That url
is the same than the one specified in the @image macro, as in intended
to be interpreted by graphics-capable info readers, such as Emacs.

The question is, how to deploy the png files referenced by the info
files?  install-info is not copying them to $infodir.  Also, since
makeinfo uses the relative paths from the @image macros, a directory
$infodir/figures/ would be needed in our specific case.  That would
surely collide with other sub directories used by other manuals.

A possible solution would be to modify 'install-info' to rewrite the
internal urls of the info files from

  [image src="figures/stream-context.png"]

to

  [image src="gnupdf/figures/stream-context.png"]

where 'gnupdf' is the basename of the info name set in

@setfilename gnupdf.info

install-info would then create the $infodir/gnupdf directory before to
copy the images referenced in the urls.

What do you think?