Re: Matlab compatible legends for FLTK/Gnuplot backends?

[David Bateman]

Ben Abbott wrote:
> On Sep 6, 2010, at 12:20 PM, David Bateman wrote:
>   
> > I'm sizing the legend relative to the axis "position" property in all cases, so that things like "southoutside" might 
> > be able to align the edges of the key with the plot (though it doesn't yet). The legend itself is placed relative to the 
> > "outerposition" of the axis if the legend is "outside" of the plot. Note that I was setting the legend 
> > "position" and "outerposition" are being set to  the same value in the legend axis as there are no axis labels, title, 
> > ticks etc to include. Looking at the way position and outerposition are autoupdating between themselves, this is probably not the right 
> > thing to do.
> >
> > However, with gnuplot
> >
> > plot(1,10); set (gca(), "activiepositionproperty", "position")
> >
> > doesn't give the same plot size as
> >
> > plot(1,10); set (gca(), "activiepositionproperty", "outerposition")
> >
> > which if I'm reading
> >
> > http://www.mathworks.com/help/techdoc/creating_plots/f1-32495.html
> >
> > correctly is not the right thing to happen. The fltk backend seems to get this 
> > right..
> >
> > D.
> >     
>
> I don't think the fltk backend bothers with the activepositionproperty at all. 
> Meaning it assumes the position property is active and essentially ignores the 
> outerposition property.
>
> To match Matlab's behavior, work needs to be done in the font end to get the 
> relationships between the position, outerposition, tightinset, and 
> activepositionproperty working correctly.
>   
Is the gnuplot behavior correct? If so then the position field of the 
axis is not updated to reflect the position of the plot determined from 
the outerposition. Could you tell me what are the coordinates of the 
axes as determined from the outerposition.

> One quick example that illustrates a gap between Octave and Matlab ...
>
>   
> > > clf
> > > axes
> > > set(gca,'outerPosition',[0.2 0.2 0.5 0.5])
> > > get(gca, 'position')
> > >       
> ans =        0.265        0.255       0.3875       0.4075
>   
> > > xlabel ('my label')
> > > get(gca, 'position')
> > >       
> ans =        0.265      0.29048       0.3875      0.37202
>
> If I infer correctly this can be handled correctly based upon your recent work. 
> If the position property for all axes were updated in the frontend then it 
> would be best for the __go_draw_*.m files to ignore the outerposition ... 
> Correct?
>   
Yes, the current code would then just work.

> If my understanding is correct, then the recent changeset I made allowing the 
> gnuplot backend to render differently depending upon the activepositionproperty 
> will need to be reverted.
>   
I see three choices

1) Revert your code as you suggest
2) Special case gnuplot in the legend function and calculate the key 
position from the outerposition value
3) Get the updating of the position from the outerposition and 
visa-versa working in the front-end

The first option is easy, but a step backwards, the second option is a 
bad idea as it introduces a dependence on the backend in the frontend 
code, and the third seems to be a large job. I'd be happy with either 1) 
or 3), but probably don't have the time to do 3) myself as I think it'll 
be a lot of trial and error and probably needs acces to matlab to test 
that the implementation is right.

D.