multi-tracks gpx

[jeromectm]

As suggested by #123, added a "trackNumber" option to return a single track, when the gpx file contains multiple ones. The name, desc etc are then returned from this track. Also added get_number_of_tracks() to count the tracks.

I am not a javascript expert, maybe there is a better way to go; but I used this like this:

var colors = ['#0000FF', '#FF00FF', '#25DB00', '#FF0000', '#00C0FF', '#FF7F00', '#A46129'];
new L.GPX(groupGpxURL, {async: true, marker_options: opts}).on('loaded', function(e) {
	var gpx = e.target;
	for (trackIdx=0; trackIdx<gpx.get_number_of_tracks(); trackIdx++) {
		var polyline_options = {
			color: colors[trackIdx % colors.length],
			opacity: 0.5,
			weight: 7,
			lineCap: 'round'
		};
		new L.GPX(groupGpxURL, {async: true, marker_options: opts, trackNumber: trackIdx, polyline_options: polyline_options}).on('loaded', function(e) {
			var gpxTrack = e.target;
			gpxTrack.addTo(map);
			layerControl.addOverlay(gpxTrack, gpxTrack.get_name());
		});
	}
});

[jeromectm]

Hello, any chance you merge this change? Thanks!

[mpetazzoni]

If the point is to be able to style each track separately, and the source GPX file can't be modified to use the GPX Style extension data as shown in https://github.com/mpetazzoni/leaflet-gpx#line-styling, I think the best option is to modify how polyline_options work to take an array of objects, applied to each track. This feels cleaner than what you're doing here, which will have you re-parse the same GPX many times just to skip over N-1 tracks each time. I'll see if I can prepare a diff for that.

[jeromectm]

One point is to style each track separately, but more importantly, as explained in #123, is to let user toggle which track to display or not.
Thanks!

[mpetazzoni]

Thanks, I'll make sure to add support for that too.