Java JMapViewer: How can I change the color of a MapPolygon?

Question

I'm creating an application for drawing pollution information on a JMapViewer. I want to do this with MapPolygons, but I didn't find a good documentation about it. I succeeded to create new MapPolygons like this:

private MapPolygon getPolygon(double lat, double lon, Color col){
    List<Coordinate> coords = new ArrayList<>();

    //add all points to the list...

    MapPolygon poly = new MapPolygonImpl(coords); 
    return poly;
}

I'm wondering how I could change the color and remove the border of the MapPolygon. There is no function setColor or such...

I tried directly with the constructor, but this doesn't work:

MapPolygon poly = new MapPolygonImpl(coords, Color.RED, new BasicStroke(0));

Does anybody know how I can change the color of the MapPolygon? Thanks!

Answer 1

Because MapPolygonImpl extends MapObjectImpl , MapPolygonImpl inherits setColor() and setBackColor() from MapObjectImpl . MapPolygonImpl uses these colors in its implementation of paint() . The colors are stored in the parent class's Style attribute, initialized by calling getDefaultStyle() during construction.

You can vary the alpha component of the chosen Color to achieve a variety of effects; the example below uses a 12.5% light gray.

MapPolygonImpl poly = new MapPolygonImpl(coords);
Color color = new Color(0x20202020, true);
poly.setColor(color);
poly.setBackColor(color);
poly.setStroke(new BasicStroke(0));
map.addMapPolygon(poly);

If the existing color is satisfactory, a similar effect may be achieved by setting the color to the background color.

MapPolygonImpl poly = new MapPolygonImpl(route);
poly.setColor(poly.getBackColor());

Answer 2

Found it out. You have to create a layer and a style:

    Layer global = new Layer("Global");
    Style style = new Style();
    style.setBackColor(col);
    style.setColor(col);
    style.setStroke(new BasicStroke(0));
    MapPolygon poly = new MapPolygonImpl(global,"",coords,style);
    return poly;