/// <summary>
/// Computes a series of driving routes from the origin, through each waypoint (in order),
/// and to the destination. The first polyline corresponds to the route from the origin to the
/// first waypoint, and the last polyline corresponds to the route from the last waypoint
/// to the destination. If <paramref name="wayPoints"/> is empty, this is equivalent
/// to <see cref="ComputeRoute(GeoCoordinates, GeoCoordinates)"/>. Will return null
/// if no route is found.
/// </summary>
/// <exception cref="ApiAccessException">Thrown if underlying API (e.g. Google Maps) returns an error.</exception>
/// <returns>A list of routes making up the journey from the origin through the waypoints to the destination. Returns
/// null if no route is found.</returns>
/// <param name="origin">Origin.</param>
/// <param name="destination">Destination.</param>
/// <param name="wayPoints">Way points.</param>
static IEnumerable <GeoPolyline> ComputeRouteWithWaypoints(GeoCoordinates origin, GeoCoordinates destination,
IEnumerable <GeoCoordinates> wayPoints)
{
List <GeoCoordinates> allWaypoints = wayPoints.ToList();
if (allWaypoints.Count == 0)
{
var route = ComputeRoute(origin, destination);
if (route == null)
{
return(null);
}
return(new List <GeoPolyline> {
route
});
}
var request = new DirectionRequest
{
Origin = origin.ToGoogleLocation(),
Destination = destination.ToGoogleLocation(),
Waypoints = allWaypoints.Select((pt) => (Location)pt.ToGoogleLocation()).ToList()
};
var response = new DirectionService().GetResponse(request);
if (response.ErrorMessage != null)
{
throw new ApiAccessException("Google Directions API failed with: " + response.ErrorMessage);
}
if (response.Routes.Length == 0)
{
return(null);
}
return(response.Routes[0].Legs
.Select((leg) => leg.Steps)
.Select((stepArray) => GeoPolyline.Join(stepArray.Select((step) => step.Polyline.ToGeo()))));
}
/// <summary>
/// Computes a driving route between two points. This may return null if
/// a route could not be found.
/// </summary>
/// <exception cref="ApiAccessException">Thrown if underlying API (e.g. Google Maps) returns an error.</exception>
/// <returns>The route.</returns>
/// <param name="origin">Origin.</param>
/// <param name="destination">Destination.</param>
static GeoPolyline ComputeRoute(GeoCoordinates origin, GeoCoordinates destination)
{
var request = new DirectionRequest
{
Origin = origin.ToGoogleLocation(),
Destination = destination.ToGoogleLocation()
};
var response = new DirectionService().GetResponse(request);
if (response.ErrorMessage != null)
{
throw new ApiAccessException("Google Directions API failed with: " + response.ErrorMessage);
}
if (response.Routes.Length == 0)
{
// This can happen if a route is not found.
return(null);
}
return(response.Routes[0].OverviewPolyline.ToGeo());
}