Show direction of linestring on map - auto zoom on map

Question

I have this code, which plots on a map a linestring which is the track of 2 coordinate points that the user supplies.

public class Quickstart {

public stati         


        

Answer 1

For the style you need something like the SLD described here, in code that becomes:

    // Create style for the line
    // Style style = SLD.createSimpleStyle(TYPE, Color.red);
    org.geotools.styling.Style style = SLD.createLineStyle(Color.red, 2.0f);
    StyleBuilder sb = new StyleBuilder();
    FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2();
    PointSymbolizer point = sb.createPointSymbolizer();
    Mark mark = sb.createMark("shape://oarrow");
    mark.setFill(sb.createFill(Color.RED));
    mark.setStroke(sb.createStroke(Color.red));

    Graphic graphic = sb.createGraphic(null, mark, null);
    graphic.setRotation(ff.function("endAngle", ff.property("line")));
    point.setGraphic(graphic);

    point.setGeometry(ff.function("endpoint", ff.property("line")));

    Rule rule = sb.createRule(point);
    style.getFeatureTypeStyles()[0].addRule(rule );
    Layer layer = new FeatureLayer(featureCollection, style);

Zooming into the line is just a case of setting the map viewport to the bounds of the line:

    MapViewport viewport = new MapViewport(featureCollection.getBounds());
    map.setViewport(viewport );

If you want you might want to grow those bounds by a little (10%?) so that you can see the surroundings too.

EDIT

To avoid the deprecated methods in StyleBuilder you can use:

style.featureTypeStyles().get(0).rules().add(rule);

Expanding the bounding box is just a case of adding some distance to the envelope:

    ReferencedEnvelope bounds = featureCollection.getBounds();
    double delta = bounds.getWidth()/20.0; //5% on each side
    bounds.expandBy(delta );
    MapViewport viewport = new MapViewport(bounds);
    map.setViewport(viewport );