Leaflet/src/layer/GeoJSON.js

/*
 * L.GeoJSON turns any GeoJSON data into a Leaflet layer.
 */

L.GeoJSON = L.FeatureGroup.extend({

	initialize: function (geojson, options) {
		L.setOptions(this, options);

		this._layers = {};

		if (geojson) {
			this.addData(geojson);
		}
	},

	addData: function (geojson) {
		var features = L.Util.isArray(geojson) ? geojson : geojson.features,
		    i, len;

		if (features) {
			for (i = 0, len = features.length; i < len; i++) {
				// Only add this if geometry or geometries are set and not null
				if (features[i].geometries || features[i].geometry || features[i].features) {
					this.addData(features[i]);
				}
			}
			return this;
		}

		var options = this.options;

		if (options.filter && !options.filter(geojson)) { return; }

		var layer = L.GeoJSON.geometryToLayer(geojson, options.pointToLayer, options.coordsToLatLng);
		layer.feature = L.GeoJSON.asFeature(geojson);

		layer.defaultOptions = layer.options;
		this.resetStyle(layer);

		if (options.onEachFeature) {
			options.onEachFeature(geojson, layer);
		}

		return this.addLayer(layer);
	},

	resetStyle: function (layer) {
		var style = this.options.style;
		if (style) {
			// reset any custom styles
			L.Util.extend(layer.options, layer.defaultOptions);

			this._setLayerStyle(layer, style);
		}
	},

	setStyle: function (style) {
		this.eachLayer(function (layer) {
			this._setLayerStyle(layer, style);
		}, this);
	},

	_setLayerStyle: function (layer, style) {
		if (typeof style === 'function') {
			style = style(layer.feature);
		}
		if (layer.setStyle) {
			layer.setStyle(style);
		}
	}
});

L.extend(L.GeoJSON, {
	geometryToLayer: function (geojson, pointToLayer, coordsToLatLng) {
		var geometry = geojson.type === 'Feature' ? geojson.geometry : geojson,
		    coords = geometry.coordinates,
		    layers = [],
		    latlng, latlngs, i, len, layer;

		coordsToLatLng = coordsToLatLng || this.coordsToLatLng;

		switch (geometry.type) {
		case 'Point':
			latlng = coordsToLatLng(coords);
			return pointToLayer ? pointToLayer(geojson, latlng) : new L.Marker(latlng);

		case 'MultiPoint':
			for (i = 0, len = coords.length; i < len; i++) {
				latlng = coordsToLatLng(coords[i]);
				layer = pointToLayer ? pointToLayer(geojson, latlng) : new L.Marker(latlng);
				layers.push(layer);
			}
			return new L.FeatureGroup(layers);

		case 'LineString':
			latlngs = this.coordsToLatLngs(coords, 0, coordsToLatLng);
			return new L.Polyline(latlngs);

		case 'Polygon':
			latlngs = this.coordsToLatLngs(coords, 1, coordsToLatLng);
			return new L.Polygon(latlngs);

		case 'MultiLineString':
			latlngs = this.coordsToLatLngs(coords, 1, coordsToLatLng);
			return new L.MultiPolyline(latlngs);

		case 'MultiPolygon':
			latlngs = this.coordsToLatLngs(coords, 2, coordsToLatLng);
			return new L.MultiPolygon(latlngs);

		case 'GeometryCollection':
			for (i = 0, len = geometry.geometries.length; i < len; i++) {

				layer = this.geometryToLayer({
					geometry: geometry.geometries[i],
					type: 'Feature',
					properties: geojson.properties
				}, pointToLayer, coordsToLatLng);

				layers.push(layer);
			}
			return new L.FeatureGroup(layers);

		default:
			throw new Error('Invalid GeoJSON object.');
		}
	},

	coordsToLatLng: function (coords) { // (Array[, Boolean]) -> LatLng
		return new L.LatLng(coords[1], coords[0]);
	},

	coordsToLatLngs: function (coords, levelsDeep, coordsToLatLng) { // (Array[, Number, Function]) -> Array
		var latlng, i, len,
		    latlngs = [];

		for (i = 0, len = coords.length; i < len; i++) {
			latlng = levelsDeep ?
			        this.coordsToLatLngs(coords[i], levelsDeep - 1, coordsToLatLng) :
			        (coordsToLatLng || this.coordsToLatLng)(coords[i]);

			latlngs.push(latlng);
		}

		return latlngs;
	},

	latLngToCoords: function (latLng) {
		return [latLng.lng, latLng.lat];
	},

	latLngsToCoords: function (latLngs) {
		var coords = [];

		for (var i = 0, len = latLngs.length; i < len; i++) {
			coords.push(L.GeoJSON.latLngToCoords(latLngs[i]));
		}

		return coords;
	},

	getFeature: function (layer, newGeometry) {
		return layer.feature ? L.extend({}, layer.feature, {geometry: newGeometry}) : L.GeoJSON.asFeature(newGeometry);
	},

	asFeature: function (geoJSON) {
		if (geoJSON.type === 'Feature') {
			return geoJSON;
		}

		return {
			type: 'Feature',
			properties: {},
			geometry: geoJSON
		};
	}
});

L.Marker.include({
	toGeoJSON: function () {
		return L.GeoJSON.getFeature(this, {
			type: 'Point',
			coordinates: L.GeoJSON.latLngToCoords(this.getLatLng())
		});
	}
});

L.Polyline.include({
	toGeoJSON: function () {
		return L.GeoJSON.getFeature(this, {
			type: 'LineString',
			coordinates: L.GeoJSON.latLngsToCoords(this.getLatLngs())
		});
	}
});

L.Polygon.include({
	toGeoJSON: function () {
		var coords = [L.GeoJSON.latLngsToCoords(this.getLatLngs())],
		    i, len, hole;

		coords[0].push(coords[0][0]);

		if (this._holes) {
			for (i = 0, len = this._holes.length; i < len; i++) {
				hole = L.GeoJSON.latLngsToCoords(this._holes[i]);
				hole.push(hole[0]);
				coords.push(hole);
			}
		}

		return L.GeoJSON.getFeature(this, {
			type: 'Polygon',
			coordinates: coords
		});
	}
});

(function () {
	function includeMulti(Klass, type) {
		Klass.include({
			toGeoJSON: function () {
				var coords = [];

				this.eachLayer(function (layer) {
					coords.push(layer.toGeoJSON().geometry.coordinates);
				});

				return L.GeoJSON.getFeature(this, {
					type: type,
					coordinates: coords
				});
			}
		});
	}

	includeMulti(L.MultiPolyline, 'MultiLineString');
	includeMulti(L.MultiPolygon, 'MultiPolygon');
}());

L.LayerGroup.include({
	toGeoJSON: function () {
		var features = [];

		this.eachLayer(function (layer) {
			if (layer.toGeoJSON) {
				features.push(L.GeoJSON.asFeature(layer.toGeoJSON()));
			}
		});

		return {
			type: 'FeatureCollection',
			features: features
		};
	}
});

L.geoJson = function (geojson, options) {
	return new L.GeoJSON(geojson, options);
};