[Kst] KstImage limitations for healpix plotting

[Ted Kisner]

George,

> > The axes on the top and bottom of the graph will be different from each
> > other, and from the Y midpoint (the PHI min/max at the midpoint sets the
> > projection). Now let's say that the user zooms in to a region of the map.
> > The axes must change based on where the zoom rectangle lies, and the type
> > of projection.
>
>   We don't support that yet.  I think we need to add it to Kst2DPlot.

ok- I think I could work around this by only displaying the lower axis scale.  
When the user zooms, I could have the datasource trigger an update, which 
would force the KstMatrix (and hence the KstImage) to reload the scaling 
information from the datasource.  Will think about this more...

> Hopefully we can use that opportunity to pull this stuff -out- of Kst2DPlot
> and into a separate class.  I would like to see it down to a maximum 2000
> lines of code again.  It's doing too much in one place, making it hard to
> understand, hard to extend, and hard to maintain.

Are you talking about making KstBaseCurve's into plugins?  I'm guessing not, 
since that wouldn't save much code.  There is definitely a ton of 
functionality in Kst2Dplot, but I'm not sure what the technically best way is 
to split it up...

>   Any reason why NaN wouldn't apply here?

That's a good idea- I guess NaN values would simply not be plotted (i.e. the 
screen pixels would be the default white color).  This is good enough for 
now.

>    You want a separate view object then?  I guess we don't have much of a
> rigid definition of Kst2DPlot.  

I'm just trying to have a detailed plan of how to implement all the necessary 
plot configurations using KstImages.  If it is not going to be possible 
without a ton of hacks, then that might indicate the need for a 
KstHealpix:KstBaseCurve.

> Maybe we need to see if it meets the 
> definition of it, perhaps by defining it.  

Hmm, so you mean we need a detailed definition of what plot scenarios need to 
be accomodated, or a definition of a proposed KstHealpix:KstBaseCurve class?  
Or both? ;-)

-Ted