GWT Openlayer draw circle vector feature

Question

stackoverflow users, I need to draw circle, in GWT wrapper for Openlayer, I have used DrawFeature, ModifyFeature controls, but not able to find control for drawing Circle, or any suggestions with example welcome. For example:

import org.gwtopenmaps.openlayers.client.control.*;    
Vector vectorLayer = new Vector("Vector Layer");    
ModifyFeature mod = new ModifyFeature(vectorLayer);

Like this is the any Draw feature for circle?

Answer 1

You want to enable DrawFeature for circle or you want to add a circle on your Layer ?

• To enable DrawFeature for circle :

  // Feature option DrawFeatureOptions drawFeatureOptions = new DrawFeatureOptions();

  // Handler option for circle
  RegularPolygonHandlerOptions handlerOptions = new RegularPolygonHandlerOptions();
  // 30 side is ok for a circle
  handlerOptions.setSides(30);
  handlerOptions.setSnapAngle(0);
  handlerOptions.setIrregular(false);
  
  // Add the handler option to the DrawFeatureOptions
  drawFeatureOptions.setHandlerOptions(handlerOptions);
  
  // create the draw feature control
  DrawFeature drawCircleFeatureControl = new DrawFeature(geometryFeaturesLayer, new RegularPolygonHandler(),
          drawFeatureOptions);
  
  // Add the control to the map
  map.addControl(drawCircleFeatureControl);
  

• To add a circle on your layer

In openlayers there is a javascript method : OpenLayers.Geometry.Polygon.createRegularPolygon I haven't be able to find it in GWT openlayers, so you had to call the javascript method :

    /**
 * Create a regular polygon around a radius. Useful for creating circles and the like.
 * 
 * @param origin {OpenLayers.Geometry.Point} center of polygon.
 * @param radius {Float} distance to vertex, in map units.
 * @param sides {Integer} Number of sides. 20 approximates a circle.
 * @param rotation {Float} original angle of rotation, in degrees.
 * @return Polygon
 */
public static native JSObject jsCreateRegularPolygon(JSObject origin, Float radius, Integer sides, Float rotation)
/*-{
    return $wnd.OpenLayers.Geometry.Polygon.createRegularPolygon(origin, radius, sides, rotation);
}-*/;

Then call it from your code in order to create your circle

JSObject polygonJSObject = jsCreateRegularPolygon(point, 100f, 30, 45f); // with 30 sides for a circle
Polygon circle = Polygon.narrowToPolygon(polygonJSObject);