support for advanced gnuplot features (was: Plotting semi-trasnparent patches?)

[Ben Abbott]

On Monday, January 26, 2009, at 02:38PM, "John W. Eaton" <jwe at octave.org> wrote:
>On 26-Jan-2009, Ben Abbott wrote:
>
>| I agree, we are missing the checkout date, but I'm not sure about checking for it. As it would only be useful for developers of octave/gnuplot, I think it is safe to assume those running 4.3 (developers sources) are able to keep their gnuplot up to date.
>| 
>| >I think we should require the most recent release version of gnuplot
>| >(4.2.4) for the octave development tree. If we can *safely* determine
>| >features of the gnuplot development tree (4.3), those could be supported
>| >too. But I would do this on case-by-case basis.
>| 
>| My understanding is that 4.2.4 is required for the developers sources ... 4.2.3 will work but not display 3D plots correctly with shading("interp").
>| 
>| >I think it is o.k. to require for a new octave release the most recent
>| >release of gnuplot (4.2.4 at the moment). But others might see this
>| >different.
>| >
>| >Kai
>| 
>| I'd also like see the conditional support for these improvements (figure position and facealpha) added to the gnuplot backend.
>| 
>| Is there a reason why we wouldn' t want to do that?
>
>I think it would be best to check for individual features, not version
>numbers.  Even if you can't find a reliable way to check for features,
>please consider writing something like this in the code that needs to
>do different things depending on what features are available:
>
>  if (gnuplot_has_foobar ())
>    ...
>  else
>    ...
>  endif
>
>  ...
>
>  function retval = gnuplot_has_foobar ()
>    persistent retval = compare_versions (__gnuplot_version__ (), "4.2.2", ">=");
>  endfunction
>
>
>This way I think it will be easier to read the code, and simpler to
>remove specific checks when/if it is safe to assume that everyone will
>have a version of gnuplot that supports a given feature.
>
>jwe

Nice idea. There still remains a version check in print.m. I'll see about modifying that and then put together a patch to allow the figure property to work under x11.

Ben