Re: [guppi-list] GNU plotutils, etc.

[Havoc Pennington <rhp zirx pair com>]

On Thu, 27 May 1999, Robert S. Maier wrote:
> 
> Glad you found the X11 scan-conversion code from plotutils useful in Guppi.
> It took a _lot_ of effort to pull it out of the X11 distribution, and clean
> it up.  The next plotutils release (2.3) will include a further cleaned-up
> version of the code as a standalone library, called "libxmi".  It should be
> much easier to drop into other source trees.  I'm going to add some
> instructions for doing that.
>

Great! Not only was it useful, it was very easy to remove from plotutils
by following the comments you had in the header file. I was contemplating
downloading the X sources and digging through those - finding this instead
was a godsend.
 
> The plotutils package, including the libplot library, will still be
> batch-oriented.  But I have real hope of making libplot's X driver more
> `widget-like', so that it can do its own redraws etc.  I'm starting to look
> at your Guppi code (it may give me some ideas for what interactivity should
> be like).
> 

It's scary stuff - there's some minimal commentary on how it works in
doc/guppi-internals.texi. 

> I've already improved libplot's API's to make them 100% reentrant, and I'm
> thinking about adding a guile interface.  For a long time I've been
> planning a higher-level library for drawing graphs, which would sit on top
> of libplot.  Maybe that should be done in guile, rather than in C or C++.
> 

That makes sense to me.

> Hope you like the new libxmi API; it's pretty clean.  For example, it
> doesn't need a `samePixel' function any more.  The basic libxmi API is now
> independent of the definition of "miPixel" (the pixel type), too.

Sounds good! This is the one thing I had to change of course, to make the
pixel match the 24-bit RGB pixels I needed, and to support alpha channel.
Then I had to modify the code that actually writes the pixels, to do the
alpha stuff if necessary.

I sort of gratuitously const-ified the public interfaces too, but, 
well, that was somewhat gratuitous.

> Incidentally I really like your adding support for an alpha channel -- I'm
> thinking of adding an alpha channel to libplot, at least for some output
> formats.
> 
> I should be releasing plotutils-2.3 within a few weeks.
> 

I have a virtual interface in Guppi for printing; so one thing I'd like to
do is support printing to a plotutils backend, so we'd have support for
all the plotutils formats. For now I don't want to add another library
requirement, but eventually I have this in mind.

When plotutils is required, I can maybe lose Guppi's special copy of
libxmi and use the one from plotutils instead.

Thanks,
Havoc