Re: Rubberband zoom

• To: Ben Monnahan <monnahan@xxxxxxxxxxxxxxxxxx>
• Subject: Re: Rubberband zoom
• From: Don Murray <dmurray@xxxxxxxxxxxxxxxx>
• Date: Wed, 07 Aug 2002 06:20:05 -0600

Ben-

Ben Monnahan wrote:

Hi, it's me again.  I would like to implement a way to zoom that would
allow the user to right click and drag a box out and then zoom in to that
box.  I have noticed something called RubberBandBoxRendererJ3D in the
javadoc and mentioned on the list.  As you may remember, I am using 2D to
create line plots.  I have been thinking(I haven't checked to see how much
work it will be) that I could possibly convert RubberBandBoxRenderJ3D to a
J2D version.  Is using this kind of thing even the best way to go about
something like this? Or is there a simpler way?  If it's going to be too
messy I may be able to deal with not having the rubberband displayed on
the screen.  In that case I'm assuming I would just need to keep track of
the mouse events.

A RubberBandBoxRendererJ2D would be a great addition to VisAD.  I
looked at it once, but didn't have the time to work on it.  We use
the RubberBandBoxRendererJ3D to zoom on our map displays.  It's
a little tricky in 3D because you have to figure out the appropriate
translations, but I basically use what MouseHelper does when it
zooms.

Also, I would like to change the way the ticks are done.  Basically I want

to force the min and max values for the scale to be in the tick list. The only way I can see to do it would be by subclassing AxisScale and

overriding the computeTicks() method.  Is there something I'm missing
where I can just tell it to use an array of vals as the tick list and
calculate it outside the class?

You can use the setLabelTable method of AxisScale to manually
set the ticks you want to see. You could use the logic in
computeTicks to calculate the "standard" ticks, then add in the
max and min values, create a hash table of these values
(key = Double(tick), value = String).  If you want a public
method for computeTicks, see Contour2D.intervalToLevels which
does essentially the same thing.  The only problem I'd see with
this approach is that if one of the calculated ticks is close
to the endpoints, the labels would overlap.  If you just want
the endpoints, then call ScalarMap.getRange() and use those
values to compute the HashTable for setLabelTable.  If you want
all this to be done automagically, then add a ScalarMapListener
to the scalarmap and recompute the table as the range changes.

Don

• References:
  • Rubberband zoom
    • From: Ben Monnahan