c# - Draw a polyline on the map using GMap.net

Question

Yep, I am not the first who is asking, but I didn't found an answer (maybe, because my english is bad). How to draw a polyline on a map? Not a route (direction), but just a polyline, like in JS Google Maps API with function Polyline. I can not understand.

Thanks anyway.

Answer 1

Although slightly overkill, you can use the GMap routes capability to draw simple lines. This also has a major advantage that it lets you determine the length of that line (in km) if necessary. Here's how you would draw a single line:

GMapRoute line_layer;
GMapOverlay line_overlay

line_layer = new GMapRoute("single_line");
line_layer.Stroke = new Pen(Brushes.Black, 2); //width and color of line

line_overlay.Routes.Add(line_layer);
gMapControl1.Overlays.Add(line_overlay)

//Once the layer is created, simply add the two points you want

line_layer.Points.Add(new PointLatLng(lat, lon));
line_layer.Points.Add(new PointLatLng(lat2, lon2));

//Note that if you are using the MouseEventArgs you need to use local coordinates and convert them:
line_layer.Points.Add(gMapControl1.FromLocalToLatLng(e.X, e.Y));

//To force the draw, you need to update the route
gMapControl1.UpdateRouteLocalPosition(line_layer);

//you can even add markers at the end of the lines by adding markers to the same layer:

GMapMarker marker_ = new GMarkerCross(p);
line_overlay.Markers.Add(marker_);