RE: [Geotools-gt2-users] Dynamically updated map

[Jonathan O. <jo...@cr...>]

Can I create an Expression that draws data from an external source, like the
value in a Map object under a key that matches the Feature's zip code
attribute, like this:

<external java.util.Map object>.get(<zipcode feature attribute>)

-----Original Message-----
From: Jesse Eichar [mailto:je...@re...]
Sent: Monday, March 13, 2006 6:00 PM
To: Jonathan Oexner
Cc: geo...@li...
Subject: Re: [Geotools-gt2-users] Dynamically updated map


If you use the FeatureStore API the map will be automatically updated  
for many of the Datastore, Shapefile for certain.  To get a  
FeatureStore use the following code:

FeatureSource source = ds.getFeatureSource("roads")
if ( source instanceof FeatureStore ){
   // data is read/write
   FeatureStore store=(FeatureStore)source;
....
} else {
    // data is read only
}


Styling is a bit more difficult because the data isn't in the  
shapefile.  Symbolizers take Expressions that determine their  
properties such as their color, line width etc...  If you don't mind  
not being to write the Style to file then you can define custom  
expressions that are used to determine the colors line widths etc...

StyleFactory provides factory methods fro creating styles that use  
Expressions to determine the properties of the styles.  Its a good  
place to look.

Hope this email makes sense...  :)

Jesse

On 13-Mar-06, at 2:45 PM, Jonathan Oexner wrote:

> Hi, I'm pretty new to Geotools (and GIS in general) so apologies if  
> the
> solution's obvious.
>
> How can I have a map that is continuously updated as new data comes  
> in?  I
> have a shapefile with all the zipcodes in a particular state, and  
> I'd like
> to turn some of them different colors based as their properties (like
> population) change over the course of a simulation.  The shapefile  
> has the
> features and the zipcodes that I can use to correlate the incoming  
> data, but
> doesn't have slots for the parameters that I need to filter on.  Any
> suggestions/hints/starting points?
>
> Thanks,
> -Jon
>
>
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