Tracking the mouse on the map

This is done by setting the mouseHandler property on a map instance to an implementation of the IMouseHandler interface. The IMouseHandler interface has the classic mouseUp, mouseDown, mouseMove abstract functions. In addition, there are two abstract functions; set map() and cleanup(). The cleanup method is called on any previously set handler before a new mouse handler is set. A map reference is "injected" (a al IoC) onto the mouse handler when it is assigned to the map using the setter function. AWX provided a base implementation (BaseMouseHandler) that has a protected helper function to convert a stage mouse location to a GeoPoint. Another provided implementation, BaseOverlayMouseHandler associates a mouse handler with a map layer. This class can be used to draw overlays on map using the mouse such as redlines and rubberband rectangles. The following implementation enables a user to draw a geodesic circle on the map. You can see it in action here. Select the "Draw Circle" from the context menu to draw a circle. Download the full source code from here.

package com.esri.sample
{
import com.esri.aws.awx.geom.CircleShape;
import com.esri.aws.awx.geom.GeoPoint;
import com.esri.aws.awx.map.handlers.BaseOverlayMouseHandler;
import com.esri.aws.awx.map.layers.OverlayLayer;
import com.esri.aws.awx.map.layers.overlays.Circle;
import com.esri.aws.awx.map.layers.overlays.style.IStyle;
import com.esri.aws.awx.map.layers.overlays.style.PolygonStyle;
import com.esri.aws.awx.map.projection.ProjUtils;

import flash.events.Event;
import flash.events.MouseEvent;

[Event(name="complete", type="flash.events.Event")]

public class CircleMouseHandler extends BaseOverlayMouseHandler
{
 private var m_down : Boolean = false;
 private var m_center : GeoPoint;
 private var m_shape : CircleShape;
 private var m_circle : Circle;

 public function CircleMouseHandler(
  overlayLayer : OverlayLayer
 )
 {
  super(
   overlayLayer,
   new PolygonStyle,
   false
  );
 }

 override public function onMouseDown(event:MouseEvent):void
 {
  m_down = true;
  m_center = stage2GeoPoint( event );
  if( m_center )
  {
   m_shape = new CircleShape( m_center, 1, CircleShape.METERS);
   m_circle = new Circle( m_shape, style );
   overlayLayer.addOverlay( m_circle );
   event.updateAfterEvent();
  }
  else
  {
   m_down = false;
   m_circle = null;
  }  
 }

 override public function onMouseMove(event:MouseEvent):void
 {
  if(m_down)
  {
   var geoPoint : GeoPoint = stage2GeoPoint(event);
   if( geoPoint )
   {
    m_shape.radius = geodeticInverse(m_center, geoPoint, ProjUtils.EARTH_RADIUS );
    m_circle.invalidateDisplayList();  
    event.updateAfterEvent();
   }
  }
 }

 override public function onMouseUp(event:MouseEvent):void
 {
  m_down = false;
  if( m_circle )
  {
   if( applyToMap == false)
   {
    overlayLayer.removeOverlay( m_circle);
   }
   event.updateAfterEvent();
   dispatchEvent( new Event(Event.COMPLETE));
  }  
 }

 private function geodeticInverse(
  fPt:GeoPoint,
  tPt:GeoPoint,
  earthRadius:Number
 ) : Number
 {
  var lam1:Number = ProjUtils.DDToRad(fPt.x), phi1:Number=ProjUtils.DDToRad(fPt.y);
  var lam2:Number = ProjUtils.DDToRad(tPt.x), phi2:Number=ProjUtils.DDToRad(tPt.y);
  var d_lam:Number = ProjUtils.Angle180(lam2 - lam1);

  var cos_phi1:Number = ProjUtils.AngleIsHalfPi(Math.abs(phi1)) ? 0.0 : Math.cos(phi1);
  var sin_phi1:Number = Math.sin(phi1);
  var cos_phi2:Number = ProjUtils.AngleIsHalfPi(Math.abs(phi2)) ? 0.0 : Math.cos(phi2);
  var sin_phi2:Number = Math.sin(phi2);

  var cos_dlam:Number = ProjUtils.AngleIsHalfPi(Math.abs(d_lam)) ? 0.0 : Math.cos(d_lam);
  var sin_dlam:Number = ProjUtils.AngleIsZero(Math.abs(d_lam)-Math.PI) ? 0.0 : Math.sin(d_lam);

  var sigma:Number = Math.acos(sin_phi1*sin_phi2 + cos_phi1*cos_phi2*cos_dlam);
  var distance:Number = sigma * earthRadius;
  return distance;
 }    
}
}