Re: [Geotools-gt2-users] Passing a feature to a function

[<tom...@co...>]

Unfortunately, that's not the behavior I'm seeing.   I create my fill function like so: 

        Fill fill = styleFactory.createFill(
                newColor,                      // function to choose feature colour
                filterFactory.literal(1.0f));  // opacity

where newColor is my external function.  When I use        JMapFrame.showMap(map);   to show the map, it makes exactly one call to newColor.evaluate(Object), where the parameter  is a SimpleFeatureImpl object containing only the geometry.   My evaluate function looks like this:

   @Override
    public Object evaluate(Object object) {
        return Color.GREEN;
    }

Unless the calling routine is "sensing" that I am returning a constant, there is no reason that this should only be called once for a map with 18,000 features.

I'm fully confident that I have screwed something up, but I have no way to identify what it is, because I have no working model to compare this to.   The model that I was working from, the "ColorLookupFunction" example/tutorial, has apparently been broken by changes in the underlying classes and was deprecated by the author anyway.    And the Javadocs are, frankly, impenetrable to a casual observer.  I don't THINK I'm an idiot, but Geotools has defeated me on this issue - I have no idea what to do next.

I simply want to draw a thematic map using a shapefile and a database - I don't think this should be this hard.   



  ----- Original Message ----- 
  From: Andrea Aime 
  To: tom...@co... 
  Cc: geo...@li... 
  Sent: Sunday, June 24, 2012 8:08 AM
  Subject: Re: [Geotools-gt2-users] Passing a feature to a function


  On Sun, Jun 24, 2012 at 4:49 PM, <tom...@co...> wrote:

    I'm looking for an example (or some documentation would be nice) on how to pass a feature to a function as you draw a map.   Conceptually I need to do this:

    fill = createFill(myFunction(feature.attribute))

    Where myFunction(feature.attribute) would go off and look up the proper fill color based on some attribute of the current feature.   (The fill color could be different for each feature, in other words).  

    The trouble I'm having is that there does not seem to be any clear example or documentation about how to pass the current feature to this function - all the examples I've  found are either deprecated or don't seem to address what I need to do. 

    Does anyone have an example they'd be willing to share, or a link to some documentation for Geotools 8.0-RC1?


  A function receives an object, when you are rendering that object is always the Feature itself, everything else is passed
  as an explicit parameter instead.


  Cheers
  Andrea

  -- 
  Ing. Andrea Aime
  GeoSolutions S.A.S.
  Tech lead

  Via Poggio alle Viti 1187
  55054  Massarosa (LU)
  Italy

  phone: +39 0584 962313
  fax:      +39 0584 962313
  mob:    +39 339 8844549

  http://www.geo-solutions.it
  http://geo-solutions.blogspot.com/
  http://www.youtube.com/user/GeoSolutionsIT
  http://www.linkedin.com/in/andreaaime
  http://twitter.com/geowolf