Re: Default Plot Characteristics, was Re: [OctDev] zplane.m marker size

[Daniel J Sebald]

Shai Ayal wrote:
> On Tue, Nov 17, 2009 at 6:14 AM, Daniel J Sebald <address@hidden> wrote:
>
> > Simon Schwarz wrote:
> >
> > > In the version of zplane.m the marker size was set explicitly to 2 I
> > > just changed this value to 12 and added a parameter for it.
> > >
> > > I just tried to remove the markersize code - it works also. The markers
> > > are tiny but bigger than before.
> >
> > That's odd.  Perhaps a marker size of 2 is some legacy code not updated to
> > fit the new Octave graphics scheme.  I just tried
> > id = plot(1:10, 'ro')
> > get(id)
> >
> > and found a marker size of 6.  I can't find exactly where the default
> > properties are set searching through the Octave source.
>
>
> the defaults for properties are set in src/graphics.h.in. search for
> markersize inside this file and you'll find it.

Oh, OK thanks.  I was searching through *.h files.


> > Anyone on the maintainers list familiar with graphics, should scripts be
> > setting any absolute sizes anymore?  Or just relative (e.g., divide by 2,
> > multiply by 3)?
>
> I'm not sure where the default came from,

Well, I would think that a markersize default of one makes sense, if it doesn't 
reflect an absolute measurement system...


> and also I'm not sure that
> marker size is consistent across backends. for the open-gl based
> backends (currently fltk) markersize is in points (i.e. 1/72 inch),
> assuming 72dpi for the screen.

That is likely where the 6 comes from, i.e., 6/72 in (1/12 in) seems a good 
default.


> There still remains some work to be done ...

OK.


> > Perhaps.  However, if a plot is the main result of the zplane() command, the
> > output of the plot command could be returned as the output of zplane().
> > Then one would have access to all the plot properties, not just marker
> > size.  One could use gcf() just as easily too.
> >
> > zplane();
> > id = gcf();
> > set(id, 'markersize', 1234)
>
> This would not work -- markersize is a property of the line object,
> not the figure object, so you would have to get the handle of the line
> object into id

Good point.  It would be a little more involved than that.

Thanks Shai,

Dan