[Geotools-gt2-users] how to get geotools to draw overlapping features?

[Matthew K. <mat...@gm...>]

Hi guys!

geotools newbie here so apologies in advance if this is a silly question or
if I abuse terminology...

I'm writing a custom layer engine for a 3rd party application that uses
geotools to draw custom rendering. I have data that occurs multiple times
per single location (fire unit responses) over many addresses, so I'm
drawing a TextSymbolizer of the integer count on top of the address to
indicate how many incidents occured there. this is all good, but the problem
I'm having is that as you zoom out the labels start to cluster together and
then geotools stops drawing some of the symbols as they overlap, so it looks
like there are fewer points of interest overall.

eg at max zoom you might see 20 addresses with incidents and associated
counts. zoom out to double, they move together and half the labels
disappear, double again and another half disappear, and so on til only one
remains.

I understand the technical reasons for this happening, but I know the client
is going to insist they see all incidents, even if they overlap or occlude.
I can manually change the drawing styles (not using SLDs, directly doing
this in Java) to use a different style at higher scales (eg just a small
circle), but I'm wondering if there's a way I can tell geotools not to
perform this optimisation so that even at high scale you can still see
overlapping symbols?

eg something like renderer.setOverlapStrategy(RenderStrategy.ALWAYS_RENDER);
//pseudo code

thanks!

my code:

// create a query for this entity with this filter (bounding box) and
returning these 3 columns
Query query = new DefaultQuery(entityName, ffilter, new String[] {
"UCV_PER_M2", entityKey, geom });
FeatureSource<SimpleFeatureType, SimpleFeature> featureSource =
dataStore.getView(query);

StyleBuilder sb = new StyleBuilder();
StyleFactory styleFactory = sb.getStyleFactory();
FilterFactory ff = sb.getFilterFactory();

List<Rule> rules = new ArrayList<Rule>();

FeatureCollection<SimpleFeatureType, SimpleFeature> fc =
featureSource.getFeatures();
// do get counts
FeatureCollection<SimpleFeatureType, SimpleFeature> copy =
featureSource.getFeatures();


Iterator<SimpleFeature> iter = fc.iterator();
try {
while (iter.hasNext()) {
SimpleFeature feature = iter.next();

String key = (String) feature.getAttribute("LAISKEY");
Color color = new Color(key.hashCode());
Stroke stroke = sb.createStroke(color, 2.0);
Fill fill = sb.createFill(color, 0.5);
Symbolizer symbolizer = sb.createPolygonSymbolizer(stroke, fill);

// create label of text
String count  = "69";
TextSymbolizer textSymbolizer = sb.createTextSymbolizer(
sb.createFill(Color.BLACK)
, new Font[] { sb.createFont("Lucida Sans", 10),sb.createFont("Arial", 10) }
, sb.createHalo()
, sb.literalExpression(count)
, new PointPlacementImpl()
, "GEOMETRY"
);



Mark circle = sb.createMark(StyleBuilder.MARK_CIRCLE, Color.RED);
Graphic graph2 = sb.createGraphic(null, circle, null, 1, 35, 0);
PointSymbolizer pointSymbolizer = sb.createPointSymbolizer(graph2);


// back to normal
Filter f = sb.getFilterFactory().equals(ff.property("LAISKEY"),
ff.literal(key));

Rule rule = styleFactory.createRule();
rule.setFilter(f);
rule.setSymbolizers(new Symbolizer[] { symbolizer, pointSymbolizer,
 textSymbolizer});
rules.add(rule);
}
} finally {
fc.close(iter);
}


FeatureTypeStyle fts = sb.createFeatureTypeStyle("Feature", (Rule[])
rules.toArray(new Rule[rules.size()]));

Style style = styleFactory.createStyle();
style.setFeatureTypeStyles(new FeatureTypeStyle[] { fts });

MapLayer mapLayer = new DefaultMapLayer(featureSource, style);
mapLayers.add(mapLayer);


Graphics2D gr = image.createGraphics();
CoordinateReferenceSystem crs =
mapDesc.getExtent().getCoordinateReferenceSystem();

LOG.debug("Creating map context");
MapContext mc = new DefaultMapContext(mapLayers.toArray(new
MapLayer[mapLayers.size()]), crs);

LOG.debug("Setting area of interest");
mc.setAreaOfInterest((ReferencedEnvelope) mapDesc.getExtent());

LOG.debug("Creating streaming renderer");
final StreamingRenderer renderer = new StreamingRenderer();

RenderingHints hints = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
renderer.setJava2DHints(hints);

renderer.setContext(mc);

Rectangle outputArea = new Rectangle(width, height);
ReferencedEnvelope dataArea = mc.getAreaOfInterest();

renderer.paint(gr, outputArea, dataArea);

--
Matthew Kerle
http://threebrightlights.blogspot.com