[Octave-bug-tracker] [bug #52842] Implement "none" as a standard option for graphics color properties

[Rik]

URL:
  <http://savannah.gnu.org/bugs/?52842>

                 Summary: Implement "none" as a standard option for graphics
color properties
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Mon 08 Jan 2018 05:07:40 PM PST
                Category: Plotting
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: Confirmed
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

It seems that most (all?) Matlab graphics objects which support a color
property support the value of "none".  This is in addition to either a string
like "magenta" or a 1x3 RGB specification.

The advantage of having no color is it allows for very selective disabling of
pieces of the plot.  For example, How do you create a baseline along the
X-axis and NO Y-axis?  You can't use the "visible" property of the axes object
because that will disable everything.  If "none" was an option then you could
do


set (gca, "Ycolor", "none")


and get what you want quite simply.

This is really just extending a feature that has already existed for certain
graphic objects, to all graphic objects.  For example, the a surface primitive
object has EdgeColor and FaceColor properties.  If I want a mesh-style graph
then I set EdgeColor to some value and FaceColor to "none".  Conversely if I
just want a surface then I set FaceColor to some value and EdgeColor to
"none".

This should be relatively simple.  libinterp/corefcn/graphics.in.h needs to be
amended to have "none" be a valid radio_property.  See the code for color
property of the figure object:


color_property color , color_property (color_values (1, 1, 1), radio_values
("none"))


Second, the toolkits that actually draw things need to be updated.  This is
libinterp/corefcn/gl-render.cc for FLTK and Qt toolkits, or
scripts/plot/util/private/__gnuplot_draw_axes__.m for gnuplot.  I care more
about the OpenGl toolkits though.





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