Re: Zooming in Applet with openmap

Hi Don,

That was an express reply and thanks for the same.
I did run the SimpleHttpImageServer and was able to create images on browser
but in this case the output from the SimpleHttpImageServer is a binary
GIF/JPEG
data, i guess which the browser displays. If i write an applet to read this
GIG/JPG
i think the applet would have to do mathematics of converting X1/Y1 - X2/Y2
mouseclick
events to Lat/Lon pairs for "Zooming on a rectangular area" .
Am i right here?
Is this kind of mathematics possible?
On the other may i know what (objects?) the LinkServer sends to a client and
what "Link"
protocol is, so that i can customize LinkServer to a servlet .
Also am i right in thinking that the shapefiles are processed by LinkServer
only and the applet
does not need to download them from webserver?
Regards
rajesh.m

Heloo Rajesh.M,

The OpenMap applet can support what you are trying to do. Although with
applets, you have to take care in choosing the source of your map data.
Access to the client's local disk is forbidden, and some layers don't
yet have the ability to use Java Resources as sources of data. That's
where the Link package comes in. The
com.bbn.openmap.layer.link.LinkLayer can communicate with a LinkServer
to, among other things, get graphics to display for a given projection
(zoom level, location, map size, etc). One more thing - the LinkServer
has to be running on the same host that the applet was loaded from in
order for the LinkLayer to contact it. Applet rules prevent an applet
from contacting a machine other than the server host.

If you want to hook OpenMap components to a servlet to create map
images, check the com.bbn.openmap.image package, specifically the
MapRequestHandler. If you want to see the MapRequestHandler used, the
SimpleHttpImageServer uses it to create map images. If you start the
SHIS and contact it on it's host and port, it will provide the format
for a valid map request.

Regards,

Don

> "Rajesh.M" wrote:
>
> Hi there,
>
> Greetings.
> Iam a new user to openmap and need to figure out if my requirement is
> possible.
> I need to develop an applet which will display the geographical
> map(say Political
> map + ocean names + countries name) and over it display some objects
> whose
> properties(say colour) would change. My problem is i have to support
> "zoom in"
> for a selected area on the map. I want to know if i could do this with
> openmap?
> I took deep look at the mailing archives and found that there is a
> package
> "com.bbn.openmap.layers.link", from what i understand could be used to
> "transfer graphic
> objects between a ClientLink and a Linkserver over socket" am i on
> the right track?
> is it possible with these classes to reply back with the new
> geographical map for the
> x/y co-ordinates area selected for zoom
> . If so is it possible to make the Linkserver a servlet and transfer
> the data over HTTP? Would be glad to get a help and detailed reply
> with information on using "Link"
> package.
>
> Thx
> Rajesh.m

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