leaflet/src/geo/crs/CRS.js

JavaScript library for mobile-friendly interactive maps

/*
 * L.CRS is the base object for all defined CRS (Coordinate Reference Systems) in Leaflet.
 */

L.CRS = {
	// converts geo coords to pixel ones
	latLngToPoint: function (latlng, zoom) {
		var projectedPoint = this.projection.project(latlng),
		    scale = this.scale(zoom);

		return this.transformation._transform(projectedPoint, scale);
	},

	// converts pixel coords to geo coords
	pointToLatLng: function (point, zoom) {
		var scale = this.scale(zoom),
		    untransformedPoint = this.transformation.untransform(point, scale);

		return this.projection.unproject(untransformedPoint);
	},

	// converts geo coords to projection-specific coords (e.g. in meters)
	project: function (latlng) {
		return this.projection.project(latlng);
	},

	// converts projected coords to geo coords
	unproject: function (point) {
		return this.projection.unproject(point);
	},

	// defines how the world scales with zoom
	scale: function (zoom) {
		return 256 * Math.pow(2, zoom);
	},

	zoom: function (scale) {
		return Math.log(scale / 256) / Math.LN2;
	},

	// returns the bounds of the world in projected coords if applicable
	getProjectedBounds: function (zoom) {
		if (this.infinite) { return null; }

		var b = this.projection.bounds,
		    s = this.scale(zoom),
		    min = this.transformation.transform(b.min, s),
		    max = this.transformation.transform(b.max, s);

		return L.bounds(min, max);
	},

	// whether a coordinate axis wraps in a given range (e.g. longitude from -180 to 180); depends on CRS
	// wrapLng: [min, max],
	// wrapLat: [min, max],

	// if true, the coordinate space will be unbounded (infinite in all directions)
	// infinite: false,

	// wraps geo coords in certain ranges if applicable
	wrapLatLng: function (latlng) {
		var lng = this.wrapLng ? L.Util.wrapNum(latlng.lng, this.wrapLng, true) : latlng.lng,
		    lat = this.wrapLat ? L.Util.wrapNum(latlng.lat, this.wrapLat, true) : latlng.lat,
		    alt = latlng.alt;

		return L.latLng(lat, lng, alt);
	}
};