[OpenMap Users] Newbie PlugIn queries

From: Donohue Sean <SGDONOHUE_at_qinetiq.com>
Date: Thu, 30 Mar 2006 14:32:06 +0100


I'm new to Java programming, so in a bit at the deep end, but I've got to
display some ship track data over DTED, and I was very happy

when I found OpenMap and all the functionality it had. I've got the
examples up and running and now the time has come to modify the

main app I have a few questions that I'd appreciate some help on please:-)


My users are going to be running the program as a client-side executable, so
I need to let them select the data files with an Open

File dialog rather than having to edit the properties file each time.


Since the track data is quite large, I like the idea of using a PlugIn to
automatically thread the process. I've added an 'Open Track

Data' menu to the file menu, and a new package
com.bbn.openmap.plugin.shipTracks (no copyright infringement intended but
I'm having

enough trouble with classpaths without adding in code from another root


Then I created class TrackPlugIn which extends AbstractPlugIn and
implemented getRectangle, but I'm stuck on how to proceed..


>From a design perspective, should the TrackPlugIn be responsible for opening
and parsing the track file? At what point does the new

thread get created, because I'd like the parsing to occur in that thread.


If LoadTrackMenuItem.actionPerformed looks like:-


JFileChooser fileChooser = FileUtils.getChooser("Open Assignment File");

int retvalue = fileChooser.showOpenDialog(null);

if (retvalue != JFileChooser.APPROVE_OPTION) {

            TrackPlugIn trackpi=new TrackPlugIn(fileChooser.getName());



Will anything nasty happen when trackpi goes out of scope, or will a
reference to it be kept somewhere else?


TrackPlugIn looks like:-

public class TrackPlugIn extends AbstractPlugIn{


    /** Creates a new instance of TrackPlugIn */

    public TrackPlugIn(String filename) {

            TrackFileParser tfp = new TrackFileParser(filename); // opens
and reads the track file

            gl = tfp.getGraphicList(); // constructs a list of OMGraphic
objects from track coordinates


            MapHandler mh = ? // how do I access the map handler object?

            PlugInLayer pil = new PlugInLayer();


            mh.add(pil); // is this all I need to do?


            // I'd like to zoom in on the region bounding the tracks, how
would I go about that please?


    protected OMGraphicList gl; // list of the track coordinates


    public OMGraphicList getRectangle(Projection p) {


            // loop through gl

            // call generate on each graphic


        return gl;




Does this look like a reasonable first step?

Once I get this working the next step will be to add a GUI so that the user
can see a table of tracks and use filters on that to

change the visibility. Because of the size of the track list it would be
nice if a single set of coordinates was used and the

OMGraphicList and table data pointed to this. Is it going to be tricky to
implement this?


Thanks for any suggestions!




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Received on Thu Mar 30 2006 - 08:42:54 EST

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