2.9.10, finally?

[John W. Eaton]

OK, I know that we need a new snapshot.  Many bugs have been fixed
since 2.9.9.  I'm ready to make a new snapshot now, but would like
some feedback first.

The graphics features have changed a lot since 2.9.9, some in ways
that are not compatible with older versions of Octave.  These changes
are likely to be among the most visible, so we need to decide whether
we should try to make plotting even better before the next snapshot or
just go ahead with it and see what the reaction is.  Here is a draft
summary of the changes that could become a NEWS file entry.

  + Compatibility with Matlab graphics is much better now.  We have
    some handle graphics (tm) features.

  + At long last, you can make a subplot and then use the print
    function to generate file with the plot.

  + RGB line colors are supported if you use gnuplot 4.2.  Octave can
    still use gnuplot 4.0, but there is no longer any way to set line
    colors with it when using the Matlab-style plot functions.
    Actually, there never was any way to do this reliably with older
    versions of gnuplot (whether run from Octave or not) since it only
    provided a limited set to choose from, and they were terminal
    dependent, so choosing color 1 with the X11 terminal would be
    different from color 1 with the PostScript terminal.

  + Finally, you can control the width of lines using (for example):

      line (x, y, "linewidth", 4, "color", [1, 0, 0.5]);

    (this also shows the color feature).

  + With gnuplot 4.2, image data is plotted with gnuplot and may be
    combined with other 2-d plot data.

  + Lines for contour plots are generated with an Octave function, so
    contour plots are now 2-d plots instead of special 3-d plots, and
    this allows you to plot additional 2-d data on top of a contour
    plot.

  - It is no longer possible to mix Matlab-style plot commands with
    the old (and now really obsolete) style of plot commands
    (__gnuplot_set__, etc.).  You can do one or the other, but not
    both for the same plot.  Really, it has never been possible to do
    this reliably, but in many cases it did work, so users were
    probably misled to believe that it should work.  Now that it
    doesn't we will probably see some complaints, but I don't guess I
    really care.  Graphics compatibility is improving, and supporting
    gnuplot-style commands directly in Octave, or trying to support
    all the features of gnuplot in Octave is not a goal.  The
    __gnuplot_*_ commands may be removed completely in a future
    version of Octave.

  - Plot property values are not extensively checked.  Specifying
    invalid property values may produce unpredictible results.

Comments?

jwe