githubmirror/Leaflet

src/map/Map.js
1 604 строки53 KB
Iván Sánchez Ortega
Implement wrapLatLngBounds (to fix #5149) (#5166)
13 янв 2017, 18:39
13 янв 2017, 18:39059a722
/*
 * @class Map
 * @aka L.Map
 * @inherits Evented
 *
 * The central class of the API — it is used to create a map on a page and manipulate it.
 *
 * @example
 *
 * ```js
 * // initialize the map on the "map" div with a given center and zoom
 * var map = L.map('map', {
 * 	center: [51.505, -0.09],
 * 	zoom: 13
 * });
 * ```
 *
 */

L.Map = L.Evented.extend({

	options: {
		// @section Map State Options
		// @option crs: CRS = L.CRS.EPSG3857
		// The [Coordinate Reference System](#crs) to use. Don't change this if you're not
		// sure what it means.
		crs: L.CRS.EPSG3857,

		// @option center: LatLng = undefined
		// Initial geographic center of the map
		center: undefined,

		// @option zoom: Number = undefined
		// Initial map zoom level
		zoom: undefined,

		// @option minZoom: Number = undefined
		// Minimum zoom level of the map. Overrides any `minZoom` option set on map layers.
		minZoom: undefined,

		// @option maxZoom: Number = undefined
		// Maximum zoom level of the map. Overrides any `maxZoom` option set on map layers.
		maxZoom: undefined,

		// @option layers: Layer[] = []
		// Array of layers that will be added to the map initially
		layers: [],

		// @option maxBounds: LatLngBounds = null
		// When this option is set, the map restricts the view to the given
		// geographical bounds, bouncing the user back if the user tries to pan
		// outside the view. To set the restriction dynamically, use
		// [`setMaxBounds`](#map-setmaxbounds) method.
		maxBounds: undefined,

		// @option renderer: Renderer = *
		// The default method for drawing vector layers on the map. `L.SVG`
		// or `L.Canvas` by default depending on browser support.
		renderer: undefined,


		// @section Animation Options
		// @option zoomAnimation: Boolean = true
		// Whether the map zoom animation is enabled. By default it's enabled
		// in all browsers that support CSS3 Transitions except Android.
		zoomAnimation: true,

		// @option zoomAnimationThreshold: Number = 4
		// Won't animate zoom if the zoom difference exceeds this value.
		zoomAnimationThreshold: 4,

		// @option fadeAnimation: Boolean = true
		// Whether the tile fade animation is enabled. By default it's enabled
		// in all browsers that support CSS3 Transitions except Android.
		fadeAnimation: true,

		// @option markerZoomAnimation: Boolean = true
		// Whether markers animate their zoom with the zoom animation, if disabled
		// they will disappear for the length of the animation. By default it's
		// enabled in all browsers that support CSS3 Transitions except Android.
		markerZoomAnimation: true,

		// @option transform3DLimit: Number = 2^23
		// Defines the maximum size of a CSS translation transform. The default
		// value should not be changed unless a web browser positions layers in
		// the wrong place after doing a large `panBy`.
		transform3DLimit: 8388608, // Precision limit of a 32-bit float

		// @section Interaction Options
		// @option zoomSnap: Number = 1
		// Forces the map's zoom level to always be a multiple of this, particularly
		// right after a [`fitBounds()`](#map-fitbounds) or a pinch-zoom.
		// By default, the zoom level snaps to the nearest integer; lower values
		// (e.g. `0.5` or `0.1`) allow for greater granularity. A value of `0`
		// means the zoom level will not be snapped after `fitBounds` or a pinch-zoom.
		zoomSnap: 1,

		// @option zoomDelta: Number = 1
		// Controls how much the map's zoom level will change after a
		// [`zoomIn()`](#map-zoomin), [`zoomOut()`](#map-zoomout), pressing `+`
		// or `-` on the keyboard, or using the [zoom controls](#control-zoom).
		// Values smaller than `1` (e.g. `0.5`) allow for greater granularity.
		zoomDelta: 1,

		// @option trackResize: Boolean = true
		// Whether the map automatically handles browser window resize to update itself.
		trackResize: true
	},

	initialize: function (id, options) { // (HTMLElement or String, Object)
		options = L.setOptions(this, options);

		this._initContainer(id);
		this._initLayout();

		// hack for https://github.com/Leaflet/Leaflet/issues/1980
		this._onResize = L.bind(this._onResize, this);

		this._initEvents();

		if (options.maxBounds) {
			this.setMaxBounds(options.maxBounds);
		}

		if (options.zoom !== undefined) {
			this._zoom = this._limitZoom(options.zoom);
		}

		if (options.center && options.zoom !== undefined) {
			this.setView(L.latLng(options.center), options.zoom, {reset: true});
		}

		this._handlers = [];
		this._layers = {};
		this._zoomBoundLayers = {};
		this._sizeChanged = true;

		this.callInitHooks();

		// don't animate on browsers without hardware-accelerated transitions or old Android/Opera
		this._zoomAnimated = L.DomUtil.TRANSITION && L.Browser.any3d && !L.Browser.mobileOpera &&
				this.options.zoomAnimation;

		// zoom transitions run with the same duration for all layers, so if one of transitionend events
		// happens after starting zoom animation (propagating to the map pane), we know that it ended globally
		if (this._zoomAnimated) {
			this._createAnimProxy();
			L.DomEvent.on(this._proxy, L.DomUtil.TRANSITION_END, this._catchTransitionEnd, this);
		}

		this._addLayers(this.options.layers);
	},


	// @section Methods for modifying map state

	// @method setView(center: LatLng, zoom: Number, options?: Zoom/pan options): this
	// Sets the view of the map (geographical center and zoom) with the given
	// animation options.
	setView: function (center, zoom, options) {

		zoom = zoom === undefined ? this._zoom : this._limitZoom(zoom);
		center = this._limitCenter(L.latLng(center), zoom, this.options.maxBounds);
		options = options || {};

		this._stop();

		if (this._loaded && !options.reset && options !== true) {

			if (options.animate !== undefined) {
				options.zoom = L.extend({animate: options.animate}, options.zoom);
				options.pan = L.extend({animate: options.animate, duration: options.duration}, options.pan);
			}

			// try animating pan or zoom
			var moved = (this._zoom !== zoom) ?
				this._tryAnimatedZoom && this._tryAnimatedZoom(center, zoom, options.zoom) :
				this._tryAnimatedPan(center, options.pan);

			if (moved) {
				// prevent resize handler call, the view will refresh after animation anyway
				clearTimeout(this._sizeTimer);
				return this;
			}
		}

		// animation didn't start, just reset the map view
		this._resetView(center, zoom);

		return this;
	},

	// @method setZoom(zoom: Number, options: Zoom/pan options): this
	// Sets the zoom of the map.
	setZoom: function (zoom, options) {
		if (!this._loaded) {
			this._zoom = zoom;
			return this;
		}
		return this.setView(this.getCenter(), zoom, {zoom: options});
	},

	// @method zoomIn(delta?: Number, options?: Zoom options): this
	// Increases the zoom of the map by `delta` ([`zoomDelta`](#map-zoomdelta) by default).
	zoomIn: function (delta, options) {
		delta = delta || (L.Browser.any3d ? this.options.zoomDelta : 1);
		return this.setZoom(this._zoom + delta, options);
	},

	// @method zoomOut(delta?: Number, options?: Zoom options): this
	// Decreases the zoom of the map by `delta` ([`zoomDelta`](#map-zoomdelta) by default).
	zoomOut: function (delta, options) {
		delta = delta || (L.Browser.any3d ? this.options.zoomDelta : 1);
		return this.setZoom(this._zoom - delta, options);
	},

	// @method setZoomAround(latlng: LatLng, zoom: Number, options: Zoom options): this
	// Zooms the map while keeping a specified geographical point on the map
	// stationary (e.g. used internally for scroll zoom and double-click zoom).
	// @alternative
	// @method setZoomAround(offset: Point, zoom: Number, options: Zoom options): this
	// Zooms the map while keeping a specified pixel on the map (relative to the top-left corner) stationary.
	setZoomAround: function (latlng, zoom, options) {
		var scale = this.getZoomScale(zoom),
		    viewHalf = this.getSize().divideBy(2),
		    containerPoint = latlng instanceof L.Point ? latlng : this.latLngToContainerPoint(latlng),

		    centerOffset = containerPoint.subtract(viewHalf).multiplyBy(1 - 1 / scale),
		    newCenter = this.containerPointToLatLng(viewHalf.add(centerOffset));

		return this.setView(newCenter, zoom, {zoom: options});
	},

	_getBoundsCenterZoom: function (bounds, options) {

		options = options || {};
		bounds = bounds.getBounds ? bounds.getBounds() : L.latLngBounds(bounds);

		var paddingTL = L.point(options.paddingTopLeft || options.padding || [0, 0]),
		    paddingBR = L.point(options.paddingBottomRight || options.padding || [0, 0]),

		    zoom = this.getBoundsZoom(bounds, false, paddingTL.add(paddingBR));

		zoom = (typeof options.maxZoom === 'number') ? Math.min(options.maxZoom, zoom) : zoom;

		var paddingOffset = paddingBR.subtract(paddingTL).divideBy(2),

		    swPoint = this.project(bounds.getSouthWest(), zoom),
		    nePoint = this.project(bounds.getNorthEast(), zoom),
		    center = this.unproject(swPoint.add(nePoint).divideBy(2).add(paddingOffset), zoom);

		return {
			center: center,
			zoom: zoom
		};
	},

	// @method fitBounds(bounds: LatLngBounds, options?: fitBounds options): this
	// Sets a map view that contains the given geographical bounds with the
	// maximum zoom level possible.
	fitBounds: function (bounds, options) {

		bounds = L.latLngBounds(bounds);

		if (!bounds.isValid()) {
			throw new Error('Bounds are not valid.');
		}

		var target = this._getBoundsCenterZoom(bounds, options);
		return this.setView(target.center, target.zoom, options);
	},

	// @method fitWorld(options?: fitBounds options): this
	// Sets a map view that mostly contains the whole world with the maximum
	// zoom level possible.
	fitWorld: function (options) {
		return this.fitBounds([[-90, -180], [90, 180]], options);
	},

	// @method panTo(latlng: LatLng, options?: Pan options): this
	// Pans the map to a given center.
	panTo: function (center, options) { // (LatLng)
		return this.setView(center, this._zoom, {pan: options});
	},

	// @method panBy(offset: Point): this
	// Pans the map by a given number of pixels (animated).
	panBy: function (offset, options) {
		offset = L.point(offset).round();
		options = options || {};

		if (!offset.x && !offset.y) {
			return this.fire('moveend');
		}
		// If we pan too far, Chrome gets issues with tiles
		// and makes them disappear or appear in the wrong place (slightly offset) #2602
		if (options.animate !== true && !this.getSize().contains(offset)) {
			this._resetView(this.unproject(this.project(this.getCenter()).add(offset)), this.getZoom());
			return this;
		}

		if (!this._panAnim) {
			this._panAnim = new L.PosAnimation();

			this._panAnim.on({
				'step': this._onPanTransitionStep,
				'end': this._onPanTransitionEnd
			}, this);
		}

		// don't fire movestart if animating inertia
		if (!options.noMoveStart) {
			this.fire('movestart');
		}

		// animate pan unless animate: false specified
		if (options.animate !== false) {
			L.DomUtil.addClass(this._mapPane, 'leaflet-pan-anim');

			var newPos = this._getMapPanePos().subtract(offset).round();
			this._panAnim.run(this._mapPane, newPos, options.duration || 0.25, options.easeLinearity);
		} else {
			this._rawPanBy(offset);
			this.fire('move').fire('moveend');
		}

		return this;
	},

	// @method flyTo(latlng: LatLng, zoom?: Number, options?: Zoom/pan options): this
	// Sets the view of the map (geographical center and zoom) performing a smooth
	// pan-zoom animation.
	flyTo: function (targetCenter, targetZoom, options) {

		options = options || {};
		if (options.animate === false || !L.Browser.any3d) {
			return this.setView(targetCenter, targetZoom, options);
		}

		this._stop();

		var from = this.project(this.getCenter()),
		    to = this.project(targetCenter),
		    size = this.getSize(),
		    startZoom = this._zoom;

		targetCenter = L.latLng(targetCenter);
		targetZoom = targetZoom === undefined ? startZoom : targetZoom;

		var w0 = Math.max(size.x, size.y),
		    w1 = w0 * this.getZoomScale(startZoom, targetZoom),
		    u1 = (to.distanceTo(from)) || 1,
		    rho = 1.42,
		    rho2 = rho * rho;

		function r(i) {
			var s1 = i ? -1 : 1,
			    s2 = i ? w1 : w0,
			    t1 = w1 * w1 - w0 * w0 + s1 * rho2 * rho2 * u1 * u1,
			    b1 = 2 * s2 * rho2 * u1,
			    b = t1 / b1,
			    sq = Math.sqrt(b * b + 1) - b;

			    // workaround for floating point precision bug when sq = 0, log = -Infinite,
			    // thus triggering an infinite loop in flyTo
			    var log = sq < 0.000000001 ? -18 : Math.log(sq);

			return log;
		}

		function sinh(n) { return (Math.exp(n) - Math.exp(-n)) / 2; }
		function cosh(n) { return (Math.exp(n) + Math.exp(-n)) / 2; }
		function tanh(n) { return sinh(n) / cosh(n); }

		var r0 = r(0);

		function w(s) { return w0 * (cosh(r0) / cosh(r0 + rho * s)); }
		function u(s) { return w0 * (cosh(r0) * tanh(r0 + rho * s) - sinh(r0)) / rho2; }

		function easeOut(t) { return 1 - Math.pow(1 - t, 1.5); }

		var start = Date.now(),
		    S = (r(1) - r0) / rho,
		    duration = options.duration ? 1000 * options.duration : 1000 * S * 0.8;

		function frame() {
			var t = (Date.now() - start) / duration,
			    s = easeOut(t) * S;

			if (t <= 1) {
				this._flyToFrame = L.Util.requestAnimFrame(frame, this);

				this._move(
					this.unproject(from.add(to.subtract(from).multiplyBy(u(s) / u1)), startZoom),
					this.getScaleZoom(w0 / w(s), startZoom),
					{flyTo: true});

			} else {
				this
					._move(targetCenter, targetZoom)
					._moveEnd(true);
			}
		}

		this._moveStart(true);

		frame.call(this);
		return this;
	},

	// @method flyToBounds(bounds: LatLngBounds, options?: fitBounds options): this
	// Sets the view of the map with a smooth animation like [`flyTo`](#map-flyto),
	// but takes a bounds parameter like [`fitBounds`](#map-fitbounds).
	flyToBounds: function (bounds, options) {
		var target = this._getBoundsCenterZoom(bounds, options);
		return this.flyTo(target.center, target.zoom, options);
	},

	// @method setMaxBounds(bounds: Bounds): this
	// Restricts the map view to the given bounds (see the [maxBounds](#map-maxbounds) option).
	setMaxBounds: function (bounds) {
		bounds = L.latLngBounds(bounds);

		if (!bounds.isValid()) {
			this.options.maxBounds = null;
			return this.off('moveend', this._panInsideMaxBounds);
		} else if (this.options.maxBounds) {
			this.off('moveend', this._panInsideMaxBounds);
		}

		this.options.maxBounds = bounds;

		if (this._loaded) {
			this._panInsideMaxBounds();
		}

		return this.on('moveend', this._panInsideMaxBounds);
	},

	// @method setMinZoom(zoom: Number): this
	// Sets the lower limit for the available zoom levels (see the [minZoom](#map-minzoom) option).
	setMinZoom: function (zoom) {
		this.options.minZoom = zoom;

		if (this._loaded && this.getZoom() < this.options.minZoom) {
			return this.setZoom(zoom);
		}

		return this;
	},

	// @method setMaxZoom(zoom: Number): this
	// Sets the upper limit for the available zoom levels (see the [maxZoom](#map-maxzoom) option).
	setMaxZoom: function (zoom) {
		this.options.maxZoom = zoom;

		if (this._loaded && (this.getZoom() > this.options.maxZoom)) {
			return this.setZoom(zoom);
		}

		return this;
	},

	// @method panInsideBounds(bounds: LatLngBounds, options?: Pan options): this
	// Pans the map to the closest view that would lie inside the given bounds (if it's not already), controlling the animation using the options specific, if any.
	panInsideBounds: function (bounds, options) {
		this._enforcingBounds = true;
		var center = this.getCenter(),
		    newCenter = this._limitCenter(center, this._zoom, L.latLngBounds(bounds));

		if (!center.equals(newCenter)) {
			this.panTo(newCenter, options);
		}

		this._enforcingBounds = false;
		return this;
	},

	// @method invalidateSize(options: Zoom/Pan options): this
	// Checks if the map container size changed and updates the map if so —
	// call it after you've changed the map size dynamically, also animating
	// pan by default. If `options.pan` is `false`, panning will not occur.
	// If `options.debounceMoveend` is `true`, it will delay `moveend` event so
	// that it doesn't happen often even if the method is called many
	// times in a row.

	// @alternative
	// @method invalidateSize(animate: Boolean): this
	// Checks if the map container size changed and updates the map if so —
	// call it after you've changed the map size dynamically, also animating
	// pan by default.
	invalidateSize: function (options) {
		if (!this._loaded) { return this; }

		options = L.extend({
			animate: false,
			pan: true
		}, options === true ? {animate: true} : options);

		var oldSize = this.getSize();
		this._sizeChanged = true;
		this._lastCenter = null;

		var newSize = this.getSize(),
		    oldCenter = oldSize.divideBy(2).round(),
		    newCenter = newSize.divideBy(2).round(),
		    offset = oldCenter.subtract(newCenter);

		if (!offset.x && !offset.y) { return this; }

		if (options.animate && options.pan) {
			this.panBy(offset);

		} else {
			if (options.pan) {
				this._rawPanBy(offset);
			}

			this.fire('move');

			if (options.debounceMoveend) {
				clearTimeout(this._sizeTimer);
				this._sizeTimer = setTimeout(L.bind(this.fire, this, 'moveend'), 200);
			} else {
				this.fire('moveend');
			}
		}

		// @section Map state change events
		// @event resize: ResizeEvent
		// Fired when the map is resized.
		return this.fire('resize', {
			oldSize: oldSize,
			newSize: newSize
		});
	},

	// @section Methods for modifying map state
	// @method stop(): this
	// Stops the currently running `panTo` or `flyTo` animation, if any.
	stop: function () {
		this.setZoom(this._limitZoom(this._zoom));
		if (!this.options.zoomSnap) {
			this.fire('viewreset');
		}
		return this._stop();
	},

	// @section Geolocation methods
	// @method locate(options?: Locate options): this
	// Tries to locate the user using the Geolocation API, firing a [`locationfound`](#map-locationfound)
	// event with location data on success or a [`locationerror`](#map-locationerror) event on failure,
	// and optionally sets the map view to the user's location with respect to
	// detection accuracy (or to the world view if geolocation failed).
	// Note that, if your page doesn't use HTTPS, this method will fail in
	// modern browsers ([Chrome 50 and newer](https://sites.google.com/a/chromium.org/dev/Home/chromium-security/deprecating-powerful-features-on-insecure-origins))
	// See `Locate options` for more details.
	locate: function (options) {

		options = this._locateOptions = L.extend({
			timeout: 10000,
			watch: false
			// setView: false
			// maxZoom: <Number>
			// maximumAge: 0
			// enableHighAccuracy: false
		}, options);

		if (!('geolocation' in navigator)) {
			this._handleGeolocationError({
				code: 0,
				message: 'Geolocation not supported.'
			});
			return this;
		}

		var onResponse = L.bind(this._handleGeolocationResponse, this),
		    onError = L.bind(this._handleGeolocationError, this);

		if (options.watch) {
			this._locationWatchId =
			        navigator.geolocation.watchPosition(onResponse, onError, options);
		} else {
			navigator.geolocation.getCurrentPosition(onResponse, onError, options);
		}
		return this;
	},

	// @method stopLocate(): this
	// Stops watching location previously initiated by `map.locate({watch: true})`
	// and aborts resetting the map view if map.locate was called with
	// `{setView: true}`.
	stopLocate: function () {
		if (navigator.geolocation && navigator.geolocation.clearWatch) {
			navigator.geolocation.clearWatch(this._locationWatchId);
		}
		if (this._locateOptions) {
			this._locateOptions.setView = false;
		}
		return this;
	},

	_handleGeolocationError: function (error) {
		var c = error.code,
		    message = error.message ||
		            (c === 1 ? 'permission denied' :
		            (c === 2 ? 'position unavailable' : 'timeout'));

		if (this._locateOptions.setView && !this._loaded) {
			this.fitWorld();
		}

		// @section Location events
		// @event locationerror: ErrorEvent
		// Fired when geolocation (using the [`locate`](#map-locate) method) failed.
		this.fire('locationerror', {
			code: c,
			message: 'Geolocation error: ' + message + '.'
		});
	},

	_handleGeolocationResponse: function (pos) {
		var lat = pos.coords.latitude,
		    lng = pos.coords.longitude,
		    latlng = new L.LatLng(lat, lng),
		    bounds = latlng.toBounds(pos.coords.accuracy),
		    options = this._locateOptions;

		if (options.setView) {
			var zoom = this.getBoundsZoom(bounds);
			this.setView(latlng, options.maxZoom ? Math.min(zoom, options.maxZoom) : zoom);
		}

		var data = {
			latlng: latlng,
			bounds: bounds,
			timestamp: pos.timestamp
		};

		for (var i in pos.coords) {
			if (typeof pos.coords[i] === 'number') {
				data[i] = pos.coords[i];
			}
		}

		// @event locationfound: LocationEvent
		// Fired when geolocation (using the [`locate`](#map-locate) method)
		// went successfully.
		this.fire('locationfound', data);
	},

	// TODO handler.addTo
	// TODO Appropiate docs section?
	// @section Other Methods
	// @method addHandler(name: String, HandlerClass: Function): this
	// Adds a new `Handler` to the map, given its name and constructor function.
	addHandler: function (name, HandlerClass) {
		if (!HandlerClass) { return this; }

		var handler = this[name] = new HandlerClass(this);

		this._handlers.push(handler);

		if (this.options[name]) {
			handler.enable();
		}

		return this;
	},

	// @method remove(): this
	// Destroys the map and clears all related event listeners.
	remove: function () {

		this._initEvents(true);

		if (this._containerId !== this._container._leaflet_id) {
			throw new Error('Map container is being reused by another instance');
		}

		try {
			// throws error in IE6-8
			delete this._container._leaflet_id;
			delete this._containerId;
		} catch (e) {
			/*eslint-disable */
			this._container._leaflet_id = undefined;
			/*eslint-enable */
			this._containerId = undefined;
		}

		L.DomUtil.remove(this._mapPane);

		if (this._clearControlPos) {
			this._clearControlPos();
		}

		this._clearHandlers();

		if (this._loaded) {
			// @section Map state change events
			// @event unload: Event
			// Fired when the map is destroyed with [remove](#map-remove) method.
			this.fire('unload');
		}

		for (var i in this._layers) {
			this._layers[i].remove();
		}

		return this;
	},

	// @section Other Methods
	// @method createPane(name: String, container?: HTMLElement): HTMLElement
	// Creates a new [map pane](#map-pane) with the given name if it doesn't exist already,
	// then returns it. The pane is created as a children of `container`, or
	// as a children of the main map pane if not set.
	createPane: function (name, container) {
		var className = 'leaflet-pane' + (name ? ' leaflet-' + name.replace('Pane', '') + '-pane' : ''),
		    pane = L.DomUtil.create('div', className, container || this._mapPane);

		if (name) {
			this._panes[name] = pane;
		}
		return pane;
	},

	// @section Methods for Getting Map State

	// @method getCenter(): LatLng
	// Returns the geographical center of the map view
	getCenter: function () {
		this._checkIfLoaded();

		if (this._lastCenter && !this._moved()) {
			return this._lastCenter;
		}
		return this.layerPointToLatLng(this._getCenterLayerPoint());
	},

	// @method getZoom(): Number
	// Returns the current zoom level of the map view
	getZoom: function () {
		return this._zoom;
	},

	// @method getBounds(): LatLngBounds
	// Returns the geographical bounds visible in the current map view
	getBounds: function () {
		var bounds = this.getPixelBounds(),
		    sw = this.unproject(bounds.getBottomLeft()),
		    ne = this.unproject(bounds.getTopRight());

		return new L.LatLngBounds(sw, ne);
	},

	// @method getMinZoom(): Number
	// Returns the minimum zoom level of the map (if set in the `minZoom` option of the map or of any layers), or `0` by default.
	getMinZoom: function () {
		return this.options.minZoom === undefined ? this._layersMinZoom || 0 : this.options.minZoom;
	},

	// @method getMaxZoom(): Number
	// Returns the maximum zoom level of the map (if set in the `maxZoom` option of the map or of any layers).
	getMaxZoom: function () {
		return this.options.maxZoom === undefined ?
			(this._layersMaxZoom === undefined ? Infinity : this._layersMaxZoom) :
			this.options.maxZoom;
	},

	// @method getBoundsZoom(bounds: LatLngBounds, inside?: Boolean): Number
	// Returns the maximum zoom level on which the given bounds fit to the map
	// view in its entirety. If `inside` (optional) is set to `true`, the method
	// instead returns the minimum zoom level on which the map view fits into
	// the given bounds in its entirety.
	getBoundsZoom: function (bounds, inside, padding) { // (LatLngBounds[, Boolean, Point]) -> Number
		bounds = L.latLngBounds(bounds);
		padding = L.point(padding || [0, 0]);

		var zoom = this.getZoom() || 0,
		    min = this.getMinZoom(),
		    max = this.getMaxZoom(),
		    nw = bounds.getNorthWest(),
		    se = bounds.getSouthEast(),
		    size = this.getSize().subtract(padding),
		    boundsSize = L.bounds(this.project(se, zoom), this.project(nw, zoom)).getSize(),
		    snap = L.Browser.any3d ? this.options.zoomSnap : 1;

		var scale = Math.min(size.x / boundsSize.x, size.y / boundsSize.y);
		zoom = this.getScaleZoom(scale, zoom);

		if (snap) {
			zoom = Math.round(zoom / (snap / 100)) * (snap / 100); // don't jump if within 1% of a snap level
			zoom = inside ? Math.ceil(zoom / snap) * snap : Math.floor(zoom / snap) * snap;
		}

		return Math.max(min, Math.min(max, zoom));
	},

	// @method getSize(): Point
	// Returns the current size of the map container (in pixels).
	getSize: function () {
		if (!this._size || this._sizeChanged) {
			this._size = new L.Point(
				this._container.clientWidth || 0,
				this._container.clientHeight || 0);

			this._sizeChanged = false;
		}
		return this._size.clone();
	},

	// @method getPixelBounds(): Bounds
	// Returns the bounds of the current map view in projected pixel
	// coordinates (sometimes useful in layer and overlay implementations).
	getPixelBounds: function (center, zoom) {
		var topLeftPoint = this._getTopLeftPoint(center, zoom);
		return new L.Bounds(topLeftPoint, topLeftPoint.add(this.getSize()));
	},

	// TODO: Check semantics - isn't the pixel origin the 0,0 coord relative to
	// the map pane? "left point of the map layer" can be confusing, specially
	// since there can be negative offsets.
	// @method getPixelOrigin(): Point
	// Returns the projected pixel coordinates of the top left point of
	// the map layer (useful in custom layer and overlay implementations).
	getPixelOrigin: function () {
		this._checkIfLoaded();
		return this._pixelOrigin;
	},

	// @method getPixelWorldBounds(zoom?: Number): Bounds
	// Returns the world's bounds in pixel coordinates for zoom level `zoom`.
	// If `zoom` is omitted, the map's current zoom level is used.
	getPixelWorldBounds: function (zoom) {
		return this.options.crs.getProjectedBounds(zoom === undefined ? this.getZoom() : zoom);
	},

	// @section Other Methods

	// @method getPane(pane: String|HTMLElement): HTMLElement
	// Returns a [map pane](#map-pane), given its name or its HTML element (its identity).
	getPane: function (pane) {
		return typeof pane === 'string' ? this._panes[pane] : pane;
	},

	// @method getPanes(): Object
	// Returns a plain object containing the names of all [panes](#map-pane) as keys and
	// the panes as values.
	getPanes: function () {
		return this._panes;
	},

	// @method getContainer: HTMLElement
	// Returns the HTML element that contains the map.
	getContainer: function () {
		return this._container;
	},


	// @section Conversion Methods

	// @method getZoomScale(toZoom: Number, fromZoom: Number): Number
	// Returns the scale factor to be applied to a map transition from zoom level
	// `fromZoom` to `toZoom`. Used internally to help with zoom animations.
	getZoomScale: function (toZoom, fromZoom) {
		// TODO replace with universal implementation after refactoring projections
		var crs = this.options.crs;
		fromZoom = fromZoom === undefined ? this._zoom : fromZoom;
		return crs.scale(toZoom) / crs.scale(fromZoom);
	},

	// @method getScaleZoom(scale: Number, fromZoom: Number): Number
	// Returns the zoom level that the map would end up at, if it is at `fromZoom`
	// level and everything is scaled by a factor of `scale`. Inverse of
	// [`getZoomScale`](#map-getZoomScale).
	getScaleZoom: function (scale, fromZoom) {
		var crs = this.options.crs;
		fromZoom = fromZoom === undefined ? this._zoom : fromZoom;
		var zoom = crs.zoom(scale * crs.scale(fromZoom));
		return isNaN(zoom) ? Infinity : zoom;
	},

	// @method project(latlng: LatLng, zoom: Number): Point
	// Projects a geographical coordinate `LatLng` according to the projection
	// of the map's CRS, then scales it according to `zoom` and the CRS's
	// `Transformation`. The result is pixel coordinate relative to
	// the CRS origin.
	project: function (latlng, zoom) {
		zoom = zoom === undefined ? this._zoom : zoom;
		return this.options.crs.latLngToPoint(L.latLng(latlng), zoom);
	},

	// @method unproject(point: Point, zoom: Number): LatLng
	// Inverse of [`project`](#map-project).
	unproject: function (point, zoom) {
		zoom = zoom === undefined ? this._zoom : zoom;
		return this.options.crs.pointToLatLng(L.point(point), zoom);
	},

	// @method layerPointToLatLng(point: Point): LatLng
	// Given a pixel coordinate relative to the [origin pixel](#map-getpixelorigin),
	// returns the corresponding geographical coordinate (for the current zoom level).
	layerPointToLatLng: function (point) {
		var projectedPoint = L.point(point).add(this.getPixelOrigin());
		return this.unproject(projectedPoint);
	},

	// @method latLngToLayerPoint(latlng: LatLng): Point
	// Given a geographical coordinate, returns the corresponding pixel coordinate
	// relative to the [origin pixel](#map-getpixelorigin).
	latLngToLayerPoint: function (latlng) {
		var projectedPoint = this.project(L.latLng(latlng))._round();
		return projectedPoint._subtract(this.getPixelOrigin());
	},

	// @method wrapLatLng(latlng: LatLng): LatLng
	// Returns a `LatLng` where `lat` and `lng` has been wrapped according to the
	// map's CRS's `wrapLat` and `wrapLng` properties, if they are outside the
	// CRS's bounds.
	// By default this means longitude is wrapped around the dateline so its
	// value is between -180 and +180 degrees.
	wrapLatLng: function (latlng) {
		return this.options.crs.wrapLatLng(L.latLng(latlng));
	},

	// @method wrapLatLngBounds(bounds: LatLngBounds): LatLngBounds
	// Returns a `LatLngBounds` with the same size as the given one, ensuring that
	// its center is within the CRS's bounds.
	// By default this means the center longitude is wrapped around the dateline so its
	// value is between -180 and +180 degrees, and the majority of the bounds
	// overlaps the CRS's bounds.
	wrapLatLngBounds: function (latlng) {
		return this.options.crs.wrapLatLngBounds(L.latLngBounds(latlng));
	},

	// @method distance(latlng1: LatLng, latlng2: LatLng): Number
	// Returns the distance between two geographical coordinates according to
	// the map's CRS. By default this measures distance in meters.
	distance: function (latlng1, latlng2) {
		return this.options.crs.distance(L.latLng(latlng1), L.latLng(latlng2));
	},

	// @method containerPointToLayerPoint(point: Point): Point
	// Given a pixel coordinate relative to the map container, returns the corresponding
	// pixel coordinate relative to the [origin pixel](#map-getpixelorigin).
	containerPointToLayerPoint: function (point) { // (Point)
		return L.point(point).subtract(this._getMapPanePos());
	},

	// @method layerPointToContainerPoint(point: Point): Point
	// Given a pixel coordinate relative to the [origin pixel](#map-getpixelorigin),
	// returns the corresponding pixel coordinate relative to the map container.
	layerPointToContainerPoint: function (point) { // (Point)
		return L.point(point).add(this._getMapPanePos());
	},

	// @method containerPointToLatLng(point: Point): LatLng
	// Given a pixel coordinate relative to the map container, returns
	// the corresponding geographical coordinate (for the current zoom level).
	containerPointToLatLng: function (point) {
		var layerPoint = this.containerPointToLayerPoint(L.point(point));
		return this.layerPointToLatLng(layerPoint);
	},

	// @method latLngToContainerPoint(latlng: LatLng): Point
	// Given a geographical coordinate, returns the corresponding pixel coordinate
	// relative to the map container.
	latLngToContainerPoint: function (latlng) {
		return this.layerPointToContainerPoint(this.latLngToLayerPoint(L.latLng(latlng)));
	},

	// @method mouseEventToContainerPoint(ev: MouseEvent): Point
	// Given a MouseEvent object, returns the pixel coordinate relative to the
	// map container where the event took place.
	mouseEventToContainerPoint: function (e) {
		return L.DomEvent.getMousePosition(e, this._container);
	},

	// @method mouseEventToLayerPoint(ev: MouseEvent): Point
	// Given a MouseEvent object, returns the pixel coordinate relative to
	// the [origin pixel](#map-getpixelorigin) where the event took place.
	mouseEventToLayerPoint: function (e) {
		return this.containerPointToLayerPoint(this.mouseEventToContainerPoint(e));
	},

	// @method mouseEventToLatLng(ev: MouseEvent): LatLng
	// Given a MouseEvent object, returns geographical coordinate where the
	// event took place.
	mouseEventToLatLng: function (e) { // (MouseEvent)
		return this.layerPointToLatLng(this.mouseEventToLayerPoint(e));
	},


	// map initialization methods

	_initContainer: function (id) {
		var container = this._container = L.DomUtil.get(id);

		if (!container) {
			throw new Error('Map container not found.');
		} else if (container._leaflet_id) {
			throw new Error('Map container is already initialized.');
		}

		L.DomEvent.addListener(container, 'scroll', this._onScroll, this);
		this._containerId = L.Util.stamp(container);
	},

	_initLayout: function () {
		var container = this._container;

		this._fadeAnimated = this.options.fadeAnimation && L.Browser.any3d;

		L.DomUtil.addClass(container, 'leaflet-container' +
			(L.Browser.touch ? ' leaflet-touch' : '') +
			(L.Browser.retina ? ' leaflet-retina' : '') +
			(L.Browser.ielt9 ? ' leaflet-oldie' : '') +
			(L.Browser.safari ? ' leaflet-safari' : '') +
			(this._fadeAnimated ? ' leaflet-fade-anim' : ''));

		var position = L.DomUtil.getStyle(container, 'position');

		if (position !== 'absolute' && position !== 'relative' && position !== 'fixed') {
			container.style.position = 'relative';
		}

		this._initPanes();

		if (this._initControlPos) {
			this._initControlPos();
		}
	},

	_initPanes: function () {
		var panes = this._panes = {};
		this._paneRenderers = {};

		// @section
		//
		// Panes are DOM elements used to control the ordering of layers on the map. You
		// can access panes with [`map.getPane`](#map-getpane) or
		// [`map.getPanes`](#map-getpanes) methods. New panes can be created with the
		// [`map.createPane`](#map-createpane) method.
		//
		// Every map has the following default panes that differ only in zIndex.
		//
		// @pane mapPane: HTMLElement = 'auto'
		// Pane that contains all other map panes

		this._mapPane = this.createPane('mapPane', this._container);
		L.DomUtil.setPosition(this._mapPane, new L.Point(0, 0));

		// @pane tilePane: HTMLElement = 200
		// Pane for `GridLayer`s and `TileLayer`s
		this.createPane('tilePane');
		// @pane overlayPane: HTMLElement = 400
		// Pane for vector overlays (`Path`s), like `Polyline`s and `Polygon`s
		this.createPane('shadowPane');
		// @pane shadowPane: HTMLElement = 500
		// Pane for overlay shadows (e.g. `Marker` shadows)
		this.createPane('overlayPane');
		// @pane markerPane: HTMLElement = 600
		// Pane for `Icon`s of `Marker`s
		this.createPane('markerPane');
		// @pane tooltipPane: HTMLElement = 650
		// Pane for tooltip.
		this.createPane('tooltipPane');
		// @pane popupPane: HTMLElement = 700
		// Pane for `Popup`s.
		this.createPane('popupPane');

		if (!this.options.markerZoomAnimation) {
			L.DomUtil.addClass(panes.markerPane, 'leaflet-zoom-hide');
			L.DomUtil.addClass(panes.shadowPane, 'leaflet-zoom-hide');
		}
	},


	// private methods that modify map state

	// @section Map state change events
	_resetView: function (center, zoom) {
		L.DomUtil.setPosition(this._mapPane, new L.Point(0, 0));

		var loading = !this._loaded;
		this._loaded = true;
		zoom = this._limitZoom(zoom);

		this.fire('viewprereset');

		var zoomChanged = this._zoom !== zoom;
		this
			._moveStart(zoomChanged)
			._move(center, zoom)
			._moveEnd(zoomChanged);

		// @event viewreset: Event
		// Fired when the map needs to redraw its content (this usually happens
		// on map zoom or load). Very useful for creating custom overlays.
		this.fire('viewreset');

		// @event load: Event
		// Fired when the map is initialized (when its center and zoom are set
		// for the first time).
		if (loading) {
			this.fire('load');
		}
	},

	_moveStart: function (zoomChanged) {
		// @event zoomstart: Event
		// Fired when the map zoom is about to change (e.g. before zoom animation).
		// @event movestart: Event
		// Fired when the view of the map starts changing (e.g. user starts dragging the map).
		if (zoomChanged) {
			this.fire('zoomstart');
		}
		return this.fire('movestart');
	},

	_move: function (center, zoom, data) {
		if (zoom === undefined) {
			zoom = this._zoom;
		}
		var zoomChanged = this._zoom !== zoom;

		this._zoom = zoom;
		this._lastCenter = center;
		this._pixelOrigin = this._getNewPixelOrigin(center);

		// @event zoom: Event
		// Fired repeatedly during any change in zoom level, including zoom
		// and fly animations.
		if (zoomChanged || (data && data.pinch)) {	// Always fire 'zoom' if pinching because #3530
			this.fire('zoom', data);
		}

		// @event move: Event
		// Fired repeatedly during any movement of the map, including pan and
		// fly animations.
		return this.fire('move', data);
	},

	_moveEnd: function (zoomChanged) {
		// @event zoomend: Event
		// Fired when the map has changed, after any animations.
		if (zoomChanged) {
			this.fire('zoomend');
		}

		// @event moveend: Event
		// Fired when the center of the map stops changing (e.g. user stopped
		// dragging the map).
		return this.fire('moveend');
	},

	_stop: function () {
		L.Util.cancelAnimFrame(this._flyToFrame);
		if (this._panAnim) {
			this._panAnim.stop();
		}
		return this;
	},

	_rawPanBy: function (offset) {
		L.DomUtil.setPosition(this._mapPane, this._getMapPanePos().subtract(offset));
	},

	_getZoomSpan: function () {
		return this.getMaxZoom() - this.getMinZoom();
	},

	_panInsideMaxBounds: function () {
		if (!this._enforcingBounds) {
			this.panInsideBounds(this.options.maxBounds);
		}
	},

	_checkIfLoaded: function () {
		if (!this._loaded) {
			throw new Error('Set map center and zoom first.');
		}
	},

	// DOM event handling

	// @section Interaction events
	_initEvents: function (remove) {
		if (!L.DomEvent) { return; }

		this._targets = {};
		this._targets[L.stamp(this._container)] = this;

		var onOff = remove ? 'off' : 'on';

		// @event click: MouseEvent
		// Fired when the user clicks (or taps) the map.
		// @event dblclick: MouseEvent
		// Fired when the user double-clicks (or double-taps) the map.
		// @event mousedown: MouseEvent
		// Fired when the user pushes the mouse button on the map.
		// @event mouseup: MouseEvent
		// Fired when the user releases the mouse button on the map.
		// @event mouseover: MouseEvent
		// Fired when the mouse enters the map.
		// @event mouseout: MouseEvent
		// Fired when the mouse leaves the map.
		// @event mousemove: MouseEvent
		// Fired while the mouse moves over the map.
		// @event contextmenu: MouseEvent
		// Fired when the user pushes the right mouse button on the map, prevents
		// default browser context menu from showing if there are listeners on
		// this event. Also fired on mobile when the user holds a single touch
		// for a second (also called long press).
		// @event keypress: KeyboardEvent
		// Fired when the user presses a key from the keyboard while the map is focused.
		L.DomEvent[onOff](this._container, 'click dblclick mousedown mouseup ' +
			'mouseover mouseout mousemove contextmenu keypress', this._handleDOMEvent, this);

		if (this.options.trackResize) {
			L.DomEvent[onOff](window, 'resize', this._onResize, this);
		}

		if (L.Browser.any3d && this.options.transform3DLimit) {
			this[onOff]('moveend', this._onMoveEnd);
		}
	},

	_onResize: function () {
		L.Util.cancelAnimFrame(this._resizeRequest);
		this._resizeRequest = L.Util.requestAnimFrame(
		        function () { this.invalidateSize({debounceMoveend: true}); }, this);
	},

	_onScroll: function () {
		this._container.scrollTop  = 0;
		this._container.scrollLeft = 0;
	},

	_onMoveEnd: function () {
		var pos = this._getMapPanePos();
		if (Math.max(Math.abs(pos.x), Math.abs(pos.y)) >= this.options.transform3DLimit) {
			// https://bugzilla.mozilla.org/show_bug.cgi?id=1203873 but Webkit also have
			// a pixel offset on very high values, see: http://jsfiddle.net/dg6r5hhb/
			this._resetView(this.getCenter(), this.getZoom());
		}
	},

	_findEventTargets: function (e, type) {
		var targets = [],
		    target,
		    isHover = type === 'mouseout' || type === 'mouseover',
		    src = e.target || e.srcElement,
		    dragging = false;

		while (src) {
			target = this._targets[L.stamp(src)];
			if (target && (type === 'click' || type === 'preclick') && !e._simulated && this._draggableMoved(target)) {
				// Prevent firing click after you just dragged an object.
				dragging = true;
				break;
			}
			if (target && target.listens(type, true)) {
				if (isHover && !L.DomEvent._isExternalTarget(src, e)) { break; }
				targets.push(target);
				if (isHover) { break; }
			}
			if (src === this._container) { break; }
			src = src.parentNode;
		}
		if (!targets.length && !dragging && !isHover && L.DomEvent._isExternalTarget(src, e)) {
			targets = [this];
		}
		return targets;
	},

	_handleDOMEvent: function (e) {
		if (!this._loaded || L.DomEvent._skipped(e)) { return; }

		var type = e.type === 'keypress' && e.keyCode === 13 ? 'click' : e.type;

		if (type === 'mousedown') {
			// prevents outline when clicking on keyboard-focusable element
			L.DomUtil.preventOutline(e.target || e.srcElement);
		}

		this._fireDOMEvent(e, type);
	},

	_fireDOMEvent: function (e, type, targets) {

		if (e.type === 'click') {
			// Fire a synthetic 'preclick' event which propagates up (mainly for closing popups).
			// @event preclick: MouseEvent
			// Fired before mouse click on the map (sometimes useful when you
			// want something to happen on click before any existing click
			// handlers start running).
			var synth = L.Util.extend({}, e);
			synth.type = 'preclick';
			this._fireDOMEvent(synth, synth.type, targets);
		}

		if (e._stopped) { return; }

		// Find the layer the event is propagating from and its parents.
		targets = (targets || []).concat(this._findEventTargets(e, type));

		if (!targets.length) { return; }

		var target = targets[0];
		if (type === 'contextmenu' && target.listens(type, true)) {
			L.DomEvent.preventDefault(e);
		}

		var data = {
			originalEvent: e
		};

		if (e.type !== 'keypress') {
			var isMarker = target instanceof L.Marker;
			data.containerPoint = isMarker ?
					this.latLngToContainerPoint(target.getLatLng()) : this.mouseEventToContainerPoint(e);
			data.layerPoint = this.containerPointToLayerPoint(data.containerPoint);
			data.latlng = isMarker ? target.getLatLng() : this.layerPointToLatLng(data.layerPoint);
		}

		for (var i = 0; i < targets.length; i++) {
			targets[i].fire(type, data, true);
			if (data.originalEvent._stopped ||
				(targets[i].options.nonBubblingEvents && L.Util.indexOf(targets[i].options.nonBubblingEvents, type) !== -1)) { return; }
		}
	},

	_draggableMoved: function (obj) {
		obj = obj.dragging && obj.dragging.enabled() ? obj : this;
		return (obj.dragging && obj.dragging.moved()) || (this.boxZoom && this.boxZoom.moved());
	},

	_clearHandlers: function () {
		for (var i = 0, len = this._handlers.length; i < len; i++) {
			this._handlers[i].disable();
		}
	},

	// @section Other Methods

	// @method whenReady(fn: Function, context?: Object): this
	// Runs the given function `fn` when the map gets initialized with
	// a view (center and zoom) and at least one layer, or immediately
	// if it's already initialized, optionally passing a function context.
	whenReady: function (callback, context) {
		if (this._loaded) {
			callback.call(context || this, {target: this});
		} else {
			this.on('load', callback, context);
		}
		return this;
	},


	// private methods for getting map state

	_getMapPanePos: function () {
		return L.DomUtil.getPosition(this._mapPane) || new L.Point(0, 0);
	},

	_moved: function () {
		var pos = this._getMapPanePos();
		return pos && !pos.equals([0, 0]);
	},

	_getTopLeftPoint: function (center, zoom) {
		var pixelOrigin = center && zoom !== undefined ?
			this._getNewPixelOrigin(center, zoom) :
			this.getPixelOrigin();
		return pixelOrigin.subtract(this._getMapPanePos());
	},

	_getNewPixelOrigin: function (center, zoom) {
		var viewHalf = this.getSize()._divideBy(2);
		return this.project(center, zoom)._subtract(viewHalf)._add(this._getMapPanePos())._round();
	},

	_latLngToNewLayerPoint: function (latlng, zoom, center) {
		var topLeft = this._getNewPixelOrigin(center, zoom);
		return this.project(latlng, zoom)._subtract(topLeft);
	},

	_latLngBoundsToNewLayerBounds: function (latLngBounds, zoom, center) {
		var topLeft = this._getNewPixelOrigin(center, zoom);
		return L.bounds([
			this.project(latLngBounds.getSouthWest(), zoom)._subtract(topLeft),
			this.project(latLngBounds.getNorthWest(), zoom)._subtract(topLeft),
			this.project(latLngBounds.getSouthEast(), zoom)._subtract(topLeft),
			this.project(latLngBounds.getNorthEast(), zoom)._subtract(topLeft)
		]);
	},

	// layer point of the current center
	_getCenterLayerPoint: function () {
		return this.containerPointToLayerPoint(this.getSize()._divideBy(2));
	},

	// offset of the specified place to the current center in pixels
	_getCenterOffset: function (latlng) {
		return this.latLngToLayerPoint(latlng).subtract(this._getCenterLayerPoint());
	},

	// adjust center for view to get inside bounds
	_limitCenter: function (center, zoom, bounds) {

		if (!bounds) { return center; }

		var centerPoint = this.project(center, zoom),
		    viewHalf = this.getSize().divideBy(2),
		    viewBounds = new L.Bounds(centerPoint.subtract(viewHalf), centerPoint.add(viewHalf)),
		    offset = this._getBoundsOffset(viewBounds, bounds, zoom);

		// If offset is less than a pixel, ignore.
		// This prevents unstable projections from getting into
		// an infinite loop of tiny offsets.
		if (offset.round().equals([0, 0])) {
			return center;
		}

		return this.unproject(centerPoint.add(offset), zoom);
	},

	// adjust offset for view to get inside bounds
	_limitOffset: function (offset, bounds) {
		if (!bounds) { return offset; }

		var viewBounds = this.getPixelBounds(),
		    newBounds = new L.Bounds(viewBounds.min.add(offset), viewBounds.max.add(offset));

		return offset.add(this._getBoundsOffset(newBounds, bounds));
	},

	// returns offset needed for pxBounds to get inside maxBounds at a specified zoom
	_getBoundsOffset: function (pxBounds, maxBounds, zoom) {
		var projectedMaxBounds = L.bounds(
		        this.project(maxBounds.getNorthEast(), zoom),
		        this.project(maxBounds.getSouthWest(), zoom)
		    ),
		    minOffset = projectedMaxBounds.min.subtract(pxBounds.min),
		    maxOffset = projectedMaxBounds.max.subtract(pxBounds.max),

		    dx = this._rebound(minOffset.x, -maxOffset.x),
		    dy = this._rebound(minOffset.y, -maxOffset.y);

		return new L.Point(dx, dy);
	},

	_rebound: function (left, right) {
		return left + right > 0 ?
			Math.round(left - right) / 2 :
			Math.max(0, Math.ceil(left)) - Math.max(0, Math.floor(right));
	},

	_limitZoom: function (zoom) {
		var min = this.getMinZoom(),
		    max = this.getMaxZoom(),
		    snap = L.Browser.any3d ? this.options.zoomSnap : 1;
		if (snap) {
			zoom = Math.round(zoom / snap) * snap;
		}
		return Math.max(min, Math.min(max, zoom));
	},

	_onPanTransitionStep: function () {
		this.fire('move');
	},

	_onPanTransitionEnd: function () {
		L.DomUtil.removeClass(this._mapPane, 'leaflet-pan-anim');
		this.fire('moveend');
	},

	_tryAnimatedPan: function (center, options) {
		// difference between the new and current centers in pixels
		var offset = this._getCenterOffset(center)._floor();

		// don't animate too far unless animate: true specified in options
		if ((options && options.animate) !== true && !this.getSize().contains(offset)) { return false; }

		this.panBy(offset, options);

		return true;
	},

	_createAnimProxy: function () {

		var proxy = this._proxy = L.DomUtil.create('div', 'leaflet-proxy leaflet-zoom-animated');
		this._panes.mapPane.appendChild(proxy);

		this.on('zoomanim', function (e) {
			var prop = L.DomUtil.TRANSFORM,
			    transform = proxy.style[prop];

			L.DomUtil.setTransform(proxy, this.project(e.center, e.zoom), this.getZoomScale(e.zoom, 1));

			// workaround for case when transform is the same and so transitionend event is not fired
			if (transform === proxy.style[prop] && this._animatingZoom) {
				this._onZoomTransitionEnd();
			}
		}, this);

		this.on('load moveend', function () {
			var c = this.getCenter(),
			    z = this.getZoom();
			L.DomUtil.setTransform(proxy, this.project(c, z), this.getZoomScale(z, 1));
		}, this);
	},

	_catchTransitionEnd: function (e) {
		if (this._animatingZoom && e.propertyName.indexOf('transform') >= 0) {
			this._onZoomTransitionEnd();
		}
	},

	_nothingToAnimate: function () {
		return !this._container.getElementsByClassName('leaflet-zoom-animated').length;
	},

	_tryAnimatedZoom: function (center, zoom, options) {

		if (this._animatingZoom) { return true; }

		options = options || {};

		// don't animate if disabled, not supported or zoom difference is too large
		if (!this._zoomAnimated || options.animate === false || this._nothingToAnimate() ||
		        Math.abs(zoom - this._zoom) > this.options.zoomAnimationThreshold) { return false; }

		// offset is the pixel coords of the zoom origin relative to the current center
		var scale = this.getZoomScale(zoom),
		    offset = this._getCenterOffset(center)._divideBy(1 - 1 / scale);

		// don't animate if the zoom origin isn't within one screen from the current center, unless forced
		if (options.animate !== true && !this.getSize().contains(offset)) { return false; }

		L.Util.requestAnimFrame(function () {
			this
			    ._moveStart(true)
			    ._animateZoom(center, zoom, true);
		}, this);

		return true;
	},

	_animateZoom: function (center, zoom, startAnim, noUpdate) {
		if (startAnim) {
			this._animatingZoom = true;

			// remember what center/zoom to set after animation
			this._animateToCenter = center;
			this._animateToZoom = zoom;

			L.DomUtil.addClass(this._mapPane, 'leaflet-zoom-anim');
		}

		// @event zoomanim: ZoomAnimEvent
		// Fired on every frame of a zoom animation
		this.fire('zoomanim', {
			center: center,
			zoom: zoom,
			noUpdate: noUpdate
		});

		// Work around webkit not firing 'transitionend', see https://github.com/Leaflet/Leaflet/issues/3689, 2693
		setTimeout(L.bind(this._onZoomTransitionEnd, this), 250);
	},

	_onZoomTransitionEnd: function () {
		if (!this._animatingZoom) { return; }

		L.DomUtil.removeClass(this._mapPane, 'leaflet-zoom-anim');

		this._animatingZoom = false;

		this._move(this._animateToCenter, this._animateToZoom);

		// This anim frame should prevent an obscure iOS webkit tile loading race condition.
		L.Util.requestAnimFrame(function () {
			this._moveEnd(true);
		}, this);
	}
});

// @section

// @factory L.map(id: String, options?: Map options)
// Instantiates a map object given the DOM ID of a `<div>` element
// and optionally an object literal with `Map options`.
//
// @alternative
// @factory L.map(el: HTMLElement, options?: Map options)
// Instantiates a map object given an instance of a `<div>` HTML element
// and optionally an object literal with `Map options`.
L.map = function (id, options) {
	return new L.Map(id, options);
};