Feature request: Support for {lat, lon} objects in LngLat#convert

[bfrengley]

Motivation

There are a number of JS libraries which deal with { lat: number; lon: number; } types rather than mapbox-gl-js' { lng: number; lat: number; }. Currently interoperating between these and mapbox-gl-js is slightly painful, with conversions required in both directions. Other mapping libraries such as Leaflet support converting from { lat: number; lon: number; } already.

Design

LngLat#convert already supports converting from { lng: number; lat: number } objects which are not instances of LngLat. If no lng is present in input, fall back to lon instead.

I am happy to make a pull request if this feature would be considered.

[jmlopez-rod]

Mapbox-gl-js: https://github.com/mapbox/mapbox-gl-js/blob/master/src/geo/lng_lat.js
Leaflet: https://github.com/Leaflet/Leaflet/blob/master/src/geo/LatLng.js

Would be nice to bring in the equals method and the utility method toLngLat.

No point in opening another issue. The same should be considered for LngLatBounds. Currently mapbox only supports extends. The contains method is a very nice utility as well as the quick toLngLatBounds.

Leaflet: https://github.com/Leaflet/Leaflet/blob/master/src/geo/LatLngBounds.js
Mapbox: https://github.com/mapbox/mapbox-gl-js/blob/master/src/geo/lng_lat_bounds.js

[bfrengley]

@mourner @jfirebaugh before I make any changes, would a pull request adding support for this be considered?

[ryanhamley]

I think this makes sense. It's a fairly small addition that improves compatibility between GL JS and other libraries.

As for the other methods mentioned: GL Native has a LngLatBounds#contains method so porting that to JS is probably a good idea. The LngLat and LngLatBounds convert methods (the JS one is here) seem like they're equivalent to toLngLat[Bounds]. An equals method is not present in Native or JS for LngLat or LngLatBounds. I'm agnostic on whether or not we should include it, but if anything I'd probably lean towards not since checking equality is easy enough to do without expanding the API.

TLDR on my two cents:
👍 to {lat, lon} support and LngLatBounds#contains if you want to include it
👎 to equals and toLngLat[Bounds]

[jmlopez-rod]

The only reason I mentioned equals is because the leaflet implementation allows us to provide a margin of error

equals: function (obj, maxMargin) {
		if (!obj) { return false; }

		obj = toLatLng(obj);

		var margin = Math.max(
		        Math.abs(this.lat - obj.lat),
		        Math.abs(this.lng - obj.lng));

		return margin <= (maxMargin === undefined ? 1.0E-9 : maxMargin);
	},

I'm guessing that was necessary since a lot of manipulations of LatLng objects leaves us with some rounding errors. Either way I'd be happy if I can remove my contains wrapper method and use the method from this library instead.

I did not realize that the toLngLat[Bounds] are already here in with the static methods convert.

[ansis]

@bfrengley I'm happy to accept a pull request adding support for lon to LngLat#convert

[ryanhamley]

Fixed by #7507