leaflet/src/geo/LatLngBounds.js

JavaScript library for mobile-friendly interactive maps

/*
 * L.LatLngBounds represents a rectangular area on the map in geographical coordinates.
 */

L.LatLngBounds = function (southWest, northEast) { // (LatLng, LatLng) or (LatLng[])
	if (!southWest) { return; }

	var latlngs = northEast ? [southWest, northEast] : southWest;

	for (var i = 0, len = latlngs.length; i < len; i++) {
		this.extend(latlngs[i]);
	}
};

L.LatLngBounds.prototype = {

	// extend the bounds to contain the given point or bounds
	extend: function (obj) { // (LatLng) or (LatLngBounds)
		var sw = this._southWest,
		    ne = this._northEast,
		    sw2, ne2;

		if (obj instanceof L.LatLng) {
			sw2 = obj;
			ne2 = obj;

		} else if (obj instanceof L.LatLngBounds) {
			sw2 = obj._southWest;
			ne2 = obj._northEast;

			if (!sw2 || !ne2) { return this; }

		} else {
			return obj ? this.extend(L.latLng(obj) || L.latLngBounds(obj)) : this;
		}

		if (!sw && !ne) {
			this._southWest = new L.LatLng(sw2.lat, sw2.lng);
			this._northEast = new L.LatLng(ne2.lat, ne2.lng);
		} else {
			sw.lat = Math.min(sw2.lat, sw.lat);
			sw.lng = Math.min(sw2.lng, sw.lng);
			ne.lat = Math.max(ne2.lat, ne.lat);
			ne.lng = Math.max(ne2.lng, ne.lng);
		}

		return this;
	},

	// extend the bounds by a percentage
	pad: function (bufferRatio) { // (Number) -> LatLngBounds
		var sw = this._southWest,
		    ne = this._northEast,
		    heightBuffer = Math.abs(sw.lat - ne.lat) * bufferRatio,
		    widthBuffer = Math.abs(sw.lng - ne.lng) * bufferRatio;

		return new L.LatLngBounds(
		        new L.LatLng(sw.lat - heightBuffer, sw.lng - widthBuffer),
		        new L.LatLng(ne.lat + heightBuffer, ne.lng + widthBuffer));
	},

	getCenter: function () { // -> LatLng
		return new L.LatLng(
		        (this._southWest.lat + this._northEast.lat) / 2,
		        (this._southWest.lng + this._northEast.lng) / 2);
	},

	getSouthWest: function () {
		return this._southWest;
	},

	getNorthEast: function () {
		return this._northEast;
	},

	getNorthWest: function () {
		return new L.LatLng(this.getNorth(), this.getWest());
	},

	getSouthEast: function () {
		return new L.LatLng(this.getSouth(), this.getEast());
	},

	getWest: function () {
		return this._southWest.lng;
	},

	getSouth: function () {
		return this._southWest.lat;
	},

	getEast: function () {
		return this._northEast.lng;
	},

	getNorth: function () {
		return this._northEast.lat;
	},

	contains: function (obj) { // (LatLngBounds) or (LatLng) -> Boolean
		if (typeof obj[0] === 'number' || obj instanceof L.LatLng) {
			obj = L.latLng(obj);
		} else {
			obj = L.latLngBounds(obj);
		}

		var sw = this._southWest,
		    ne = this._northEast,
		    sw2, ne2;

		if (obj instanceof L.LatLngBounds) {
			sw2 = obj.getSouthWest();
			ne2 = obj.getNorthEast();
		} else {
			sw2 = ne2 = obj;
		}

		return (sw2.lat >= sw.lat) && (ne2.lat <= ne.lat) &&
		       (sw2.lng >= sw.lng) && (ne2.lng <= ne.lng);
	},

	intersects: function (bounds) { // (LatLngBounds) -> Boolean
		bounds = L.latLngBounds(bounds);

		var sw = this._southWest,
		    ne = this._northEast,
		    sw2 = bounds.getSouthWest(),
		    ne2 = bounds.getNorthEast(),

		    latIntersects = (ne2.lat >= sw.lat) && (sw2.lat <= ne.lat),
		    lngIntersects = (ne2.lng >= sw.lng) && (sw2.lng <= ne.lng);

		return latIntersects && lngIntersects;
	},

	overlaps: function (bounds) { // (LatLngBounds) -> Boolean
		bounds = L.latLngBounds(bounds);

		var sw = this._southWest,
		    ne = this._northEast,
		    sw2 = bounds.getSouthWest(),
		    ne2 = bounds.getNorthEast(),

		    latOverlaps = (ne2.lat > sw.lat) && (sw2.lat < ne.lat),
		    lngOverlaps = (ne2.lng > sw.lng) && (sw2.lng < ne.lng);

		return latOverlaps && lngOverlaps;
	},

	toBBoxString: function () {
		return [this.getWest(), this.getSouth(), this.getEast(), this.getNorth()].join(',');
	},

	equals: function (bounds) { // (LatLngBounds)
		if (!bounds) { return false; }

		bounds = L.latLngBounds(bounds);

		return this._southWest.equals(bounds.getSouthWest()) &&
		       this._northEast.equals(bounds.getNorthEast());
	},

	isValid: function () {
		return !!(this._southWest && this._northEast);
	}
};

// TODO International date line?

L.latLngBounds = function (a, b) { // (LatLngBounds) or (LatLng, LatLng)
	if (!a || a instanceof L.LatLngBounds) {
		return a;
	}
	return new L.LatLngBounds(a, b);
};