Re: MapProjectionDisplay question

Don Murray wrote:

Yeah, that draw command used to get me all the time.too!  That's
kind of left over from the old VisAD days when anything you
did to a display caused a redraw.  The idea was that you could
create the DisplayMaster, add all the displayables, then call draw()
which would render everything.  These days, you can add and
remove displayables with much less overhead. In the IDV, we
use the ViewManager classes (wrapper around a DisplayMaster)
to call draw so in most cases it's "automatic".

Hi Don, hmm your comments above have me thinking. My app is web based, and I am using idv/visad classes in 'offscreen' mode. I want to generate BufferedImages (sent to the web client as transparent pngs), using e.g. the getImage() call.

With the 'reduced overhead' to which you are referring, would I better off adding many Displayables to one DisplayMaster, and turning the visibility of each on and off to grab each BufferedImage, or use a separate DisplayMaster, each with a single Displayable? The former is better in a web environment, since fewer objects to clean up when the user 'session' expires.

Your comments welcomed.