Right :-)
We have a tutorial for uDig that does a similar "moving dot" problem.
So it is time to dive into Java2D voodoo and reproduce the idea of a glass pane
under your control.
Basic idea is to draw into two (or more) separate buffers yourself.
You can look up "volitile" image as a graphics mode; you can daw your two
buffers (one for the map; and one for your visual feedback) into the live
buffer employed by the graphics card.
http://download.oracle.com/javase/6/docs/api/java/awt/image/VolatileImage.html
Make sure to only draw your (already built) buffers in the validate(
graphicsConfiguration ) loop; do not try doing any math or calculation as you
draw; etc...
--
Jody Garnett
On Thursday, 28 April 2011 at 11:28 PM, Francesca Martelli wrote:
> Thank you Jody, but I would like to draw directly on the screen, since
> the point changes its coordinates frequently and if I create a feature
> collection, each time I change the point, the entire map is repainted
> causing a flickering effect. The application is a kind of GPS navigator:
> there is a map (map context with a number of shapefile in UTM) and I
> need to represent a moving vehicle.
>
> I have already tried to use the glass pane, but this does not solve the
> problem since it is not possible to clear the glass pane, so old
> positions remain painted over that. The only way I found for cleaning
> the glass pane is to set visibility to false and to true again, but this
> provokes flickering!!!
>
> So, I was looking for a different approach...
> francesca
>
>
> Il giorno gio, 28/04/2011 alle 23.15 +1000, Jody Garnett ha scritto:
> > Perhaps you can define a feature collection (in memory) with your
> > point; declare the correct coordinate reference system for your UTM
> > zone (when you do this).
> >
> >
> > And then add that FeatureCollection to the screen as a separate layer?
> >
> >
> > There are a number of FeatureCollection implementations available for
> > you to work with:
> > -http://docs.geotools.org/latest/userguide/library/main/collection.html
> >
> >
> > The indexed one is very fast to display (but not suitable for use if
> > you are changing your point).
> >
> >
> > Jody
> >
> > On Thu, Apr 28, 2011 at 10:52 PM, Francesca Martelli
> > <[email protected]> wrote:
> > Hi all,
> > I have a problem with translation from utm coordinates in
> > screen pixel
> > position. I have already seen the tutorials (world2screen,
> > data2world...), but examples reported there seem do not work
> > in my case.
> >
> > I have a mapContext with shapefiles in a jmappane, and I would
> > like to
> > paint a point (with position expressed in UTM coordinates)
> > over the map.
> >
> > Any help is greatly appreciated.
> > Francesca
> >
> >
> > --
> > Francesca Martelli, Computer Science Ph.D.
> > Algorithms and Computational Mathematics Group, IIT - CNR,
> > Pisa
> > Phone: +39 050 315 3191 (office), +39 050 315 2333 (fax)
> > http://www.iit.cnr.it/francesca.martelli/
> > email: [email protected]
> >
> >
> >
> >
> > ------------------------------------------------------------------------------
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>
>
> --
> Francesca Martelli, Computer Science Ph.D.
> Algorithms and Computational Mathematics Group, IIT - CNR, Pisa
> Phone: +39 050 315 3191 (office), +39 050 315 2333 (fax)
> http://www.iit.cnr.it/francesca.martelli/
> email: [email protected]
>
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