MarkerCluster.Spiderfier.js

//This code is 100% based on https://github.com/jawj/OverlappingMarkerSpiderfier-Leaflet
//Huge thanks to jawj for implementing it first to make my job easy :-)

L.MarkerCluster.include({

	_2PI: Math.PI * 2,
	_circleFootSeparation: 25, //related to circumference of circle
	_circleStartAngle: 0,

	_spiralFootSeparation:  28, //related to size of spiral (experiment!)
	_spiralLengthStart: 11,
	_spiralLengthFactor: 5,

	_circleSpiralSwitchover: 9, //show spiral instead of circle from this marker count upwards.
								// 0 -> always spiral; Infinity -> always circle

	spiderfy: function () {
		if (this._group._spiderfied === this || this._group._inZoomAnimation) {
			return;
		}

		var childMarkers = this.getAllChildMarkers(null, true),
			group = this._group,
			map = group._map,
			center = map.latLngToLayerPoint(this._latlng),
			positions;

		this._group._unspiderfy();
		this._group._spiderfied = this;

		//TODO Maybe: childMarkers order by distance to center

		if (this._group.options.spiderfyShapePositions) {
			positions = this._group.options.spiderfyShapePositions(childMarkers.length, center);
		} else if (childMarkers.length >= this._circleSpiralSwitchover) {
			positions = this._generatePointsSpiral(childMarkers.length, center);
		} else {
			center.y += 10; // Otherwise circles look wrong => hack for standard blue icon, renders differently for other icons.
			positions = this._generatePointsCircle(childMarkers.length, center);
		}

		this._animationSpiderfy(childMarkers, positions);
	},

	unspiderfy: function (zoomDetails) {
		/// <param Name="zoomDetails">Argument from zoomanim if being called in a zoom animation or null otherwise</param>
		if (this._group._inZoomAnimation) {
			return;
		}
		this._animationUnspiderfy(zoomDetails);

		this._group._spiderfied = null;
	},

	_generatePointsCircle: function (count, centerPt) {
		var circumference = this._group.options.spiderfyDistanceMultiplier * this._circleFootSeparation * (2 + count),
			legLength = circumference / this._2PI,  //radius from circumference
			angleStep = this._2PI / count,
			res = [],
			i, angle;

		legLength = Math.max(legLength, 35); // Minimum distance to get outside the cluster icon.

		res.length = count;

		for (i = 0; i < count; i++) { // Clockwise, like spiral.
			angle = this._circleStartAngle + i * angleStep;
			res[i] = new L.Point(centerPt.x + legLength * Math.cos(angle), centerPt.y + legLength * Math.sin(angle))._round();
		}

		return res;
	},

	_generatePointsSpiral: function (count, centerPt) {
		var spiderfyDistanceMultiplier = this._group.options.spiderfyDistanceMultiplier,
			legLength = spiderfyDistanceMultiplier * this._spiralLengthStart,
			separation = spiderfyDistanceMultiplier * this._spiralFootSeparation,
			lengthFactor = spiderfyDistanceMultiplier * this._spiralLengthFactor * this._2PI,
			angle = 0,
			res = [],
			i;

		res.length = count;

		// Higher index, closer position to cluster center.
		for (i = count; i >= 0; i--) {
			// Skip the first position, so that we are already farther from center and we avoid
			// being under the default cluster icon (especially important for Circle Markers).
			if (i < count) {
				res[i] = new L.Point(centerPt.x + legLength * Math.cos(angle), centerPt.y + legLength * Math.sin(angle))._round();
			}
			angle += separation / legLength + i * 0.0005;
			legLength += lengthFactor / angle;
		}
		return res;
	},

	_noanimationUnspiderfy: function () {
		var group = this._group,
			map = group._map,
			fg = group._featureGroup,
			childMarkers = this.getAllChildMarkers(null, true),
			m, i;

		group._ignoreMove = true;

		this.setOpacity(1);
		for (i = childMarkers.length - 1; i >= 0; i--) {
			m = childMarkers[i];

			fg.removeLayer(m);

			if (m._preSpiderfyLatlng) {
				m.setLatLng(m._preSpiderfyLatlng);
				delete m._preSpiderfyLatlng;
			}
			if (m.setZIndexOffset) {
				m.setZIndexOffset(0);
			}

			if (m._spiderLeg) {
				map.removeLayer(m._spiderLeg);
				delete m._spiderLeg;
			}
		}

		group.fire('unspiderfied', {
			cluster: this,
			markers: childMarkers
		});
		group._ignoreMove = false;
		group._spiderfied = null;
	}
});

//Non Animated versions of everything
L.MarkerClusterNonAnimated = L.MarkerCluster.extend({
	_animationSpiderfy: function (childMarkers, positions) {
		var group = this._group,
			map = group._map,
			fg = group._featureGroup,
			legOptions = this._group.options.spiderLegPolylineOptions,
			i, m, leg, newPos;

		group._ignoreMove = true;

		// Traverse in ascending order to make sure that inner circleMarkers are on top of further legs. Normal markers are re-ordered by newPosition.
		// The reverse order trick no longer improves performance on modern browsers.
		for (i = 0; i < childMarkers.length; i++) {
			newPos = map.layerPointToLatLng(positions[i]);
			m = childMarkers[i];

			// Add the leg before the marker, so that in case the latter is a circleMarker, the leg is behind it.
			leg = new L.Polyline([this._latlng, newPos], legOptions);
			map.addLayer(leg);
			m._spiderLeg = leg;

			// Now add the marker.
			m._preSpiderfyLatlng = m._latlng;
			m.setLatLng(newPos);
			if (m.setZIndexOffset) {
				m.setZIndexOffset(1000000); //Make these appear on top of EVERYTHING
			}

			fg.addLayer(m);
		}
		this.setOpacity(0.3);

		group._ignoreMove = false;
		group.fire('spiderfied', {
			cluster: this,
			markers: childMarkers
		});
	},

	_animationUnspiderfy: function () {
		this._noanimationUnspiderfy();
	}
});

//Animated versions here
L.MarkerCluster.include({

	_animationSpiderfy: function (childMarkers, positions) {
		var me = this,
			group = this._group,
			map = group._map,
			fg = group._featureGroup,
			thisLayerLatLng = this._latlng,
			thisLayerPos = map.latLngToLayerPoint(thisLayerLatLng),
			svg = L.Path.SVG,
			legOptions = L.extend({}, this._group.options.spiderLegPolylineOptions), // Copy the options so that we can modify them for animation.
			finalLegOpacity = legOptions.opacity,
			i, m, leg, legPath, legLength, newPos;

		if (finalLegOpacity === undefined) {
			finalLegOpacity = L.MarkerClusterGroup.prototype.options.spiderLegPolylineOptions.opacity;
		}

		if (svg) {
			// If the initial opacity of the spider leg is not 0 then it appears before the animation starts.
			legOptions.opacity = 0;

			// Add the class for CSS transitions.
			legOptions.className = (legOptions.className || '') + ' leaflet-cluster-spider-leg';
		} else {
			// Make sure we have a defined opacity.
			legOptions.opacity = finalLegOpacity;
		}

		group._ignoreMove = true;

		// Add markers and spider legs to map, hidden at our center point.
		// Traverse in ascending order to make sure that inner circleMarkers are on top of further legs. Normal markers are re-ordered by newPosition.
		// The reverse order trick no longer improves performance on modern browsers.
		for (i = 0; i < childMarkers.length; i++) {
			m = childMarkers[i];

			newPos = map.layerPointToLatLng(positions[i]);

			// Add the leg before the marker, so that in case the latter is a circleMarker, the leg is behind it.
			leg = new L.Polyline([thisLayerLatLng, newPos], legOptions);
			map.addLayer(leg);
			m._spiderLeg = leg;

			// Explanations: https://jakearchibald.com/2013/animated-line-drawing-svg/
			// In our case the transition property is declared in the CSS file.
			if (svg) {
				legPath = leg._path;
				legLength = legPath.getTotalLength() + 0.1; // Need a small extra length to avoid remaining dot in Firefox.
				legPath.style.strokeDasharray = legLength; // Just 1 length is enough, it will be duplicated.
				legPath.style.strokeDashoffset = legLength;
			}

			// If it is a marker, add it now and we'll animate it out
			if (m.setZIndexOffset) {
				m.setZIndexOffset(1000000); // Make normal markers appear on top of EVERYTHING
			}
			if (m.clusterHide) {
				m.clusterHide();
			}
			
			// Vectors just get immediately added
			fg.addLayer(m);

			if (m._setPos) {
				m._setPos(thisLayerPos);
			}
		}

		group._forceLayout();
		group._animationStart();

		// Reveal markers and spider legs.
		for (i = childMarkers.length - 1; i >= 0; i--) {
			newPos = map.layerPointToLatLng(positions[i]);
			m = childMarkers[i];

			//Move marker to new position
			m._preSpiderfyLatlng = m._latlng;
			m.setLatLng(newPos);
			
			if (m.clusterShow) {
				m.clusterShow();
			}

			// Animate leg (animation is actually delegated to CSS transition).
			if (svg) {
				leg = m._spiderLeg;
				legPath = leg._path;
				legPath.style.strokeDashoffset = 0;
				//legPath.style.strokeOpacity = finalLegOpacity;
				leg.setStyle({opacity: finalLegOpacity});
			}
		}
		this.setOpacity(0.3);

		group._ignoreMove = false;

		setTimeout(function () {
			group._animationEnd();
			group.fire('spiderfied', {
				cluster: me,
				markers: childMarkers
			});
		}, 200);
	},

	_animationUnspiderfy: function (zoomDetails) {
		var me = this,
			group = this._group,
			map = group._map,
			fg = group._featureGroup,
			thisLayerPos = zoomDetails ? map._latLngToNewLayerPoint(this._latlng, zoomDetails.zoom, zoomDetails.center) : map.latLngToLayerPoint(this._latlng),
			childMarkers = this.getAllChildMarkers(null, true),
			svg = L.Path.SVG,
			m, i, leg, legPath, legLength, nonAnimatable;

		group._ignoreMove = true;
		group._animationStart();

		//Make us visible and bring the child markers back in
		this.setOpacity(1);
		for (i = childMarkers.length - 1; i >= 0; i--) {
			m = childMarkers[i];

			//Marker was added to us after we were spiderfied
			if (!m._preSpiderfyLatlng) {
				continue;
			}

			//Close any popup on the marker first, otherwise setting the location of the marker will make the map scroll
			m.closePopup();

			//Fix up the location to the real one
			m.setLatLng(m._preSpiderfyLatlng);
			delete m._preSpiderfyLatlng;

			//Hack override the location to be our center
			nonAnimatable = true;
			if (m._setPos) {
				m._setPos(thisLayerPos);
				nonAnimatable = false;
			}
			if (m.clusterHide) {
				m.clusterHide();
				nonAnimatable = false;
			}
			if (nonAnimatable) {
				fg.removeLayer(m);
			}

			// Animate the spider leg back in (animation is actually delegated to CSS transition).
			if (svg) {
				leg = m._spiderLeg;
				legPath = leg._path;
				legLength = legPath.getTotalLength() + 0.1;
				legPath.style.strokeDashoffset = legLength;
				leg.setStyle({opacity: 0});
			}
		}

		group._ignoreMove = false;

		setTimeout(function () {
			//If we have only <= one child left then that marker will be shown on the map so don't remove it!
			var stillThereChildCount = 0;
			for (i = childMarkers.length - 1; i >= 0; i--) {
				m = childMarkers[i];
				if (m._spiderLeg) {
					stillThereChildCount++;
				}
			}


			for (i = childMarkers.length - 1; i >= 0; i--) {
				m = childMarkers[i];

				if (!m._spiderLeg) { //Has already been unspiderfied
					continue;
				}

				if (m.clusterShow) {
					m.clusterShow();
				}
				if (m.setZIndexOffset) {
					m.setZIndexOffset(0);
				}

				if (stillThereChildCount > 1) {
					fg.removeLayer(m);
				}

				map.removeLayer(m._spiderLeg);
				delete m._spiderLeg;
			}
			group._animationEnd();
			group.fire('unspiderfied', {
				cluster: me,
				markers: childMarkers
			});
		}, 200);
	}
});


L.MarkerClusterGroup.include({
	//The MarkerCluster currently spiderfied (if any)
	_spiderfied: null,

	unspiderfy: function () {
		this._unspiderfy.apply(this, arguments);
	},

	_spiderfierOnAdd: function () {
		this._map.on('click', this._unspiderfyWrapper, this);

		if (this._map.options.zoomAnimation) {
			this._map.on('zoomstart', this._unspiderfyZoomStart, this);
		}
		//Browsers without zoomAnimation or a big zoom don't fire zoomstart
		this._map.on('zoomend', this._noanimationUnspiderfy, this);

		if (!L.Browser.touch) {
			this._map.getRenderer(this);
			//Needs to happen in the pageload, not after, or animations don't work in webkit
			//  http://stackoverflow.com/questions/8455200/svg-animate-with-dynamically-added-elements
			//Disable on touch browsers as the animation messes up on a touch zoom and isn't very noticable
		}
	},

	_spiderfierOnRemove: function () {
		this._map.off('click', this._unspiderfyWrapper, this);
		this._map.off('zoomstart', this._unspiderfyZoomStart, this);
		this._map.off('zoomanim', this._unspiderfyZoomAnim, this);
		this._map.off('zoomend', this._noanimationUnspiderfy, this);

		//Ensure that markers are back where they should be
		// Use no animation to avoid a sticky leaflet-cluster-anim class on mapPane
		this._noanimationUnspiderfy();
	},

	//On zoom start we add a zoomanim handler so that we are guaranteed to be last (after markers are animated)
	//This means we can define the animation they do rather than Markers doing an animation to their actual location
	_unspiderfyZoomStart: function () {
		if (!this._map) { //May have been removed from the map by a zoomEnd handler
			return;
		}

		this._map.on('zoomanim', this._unspiderfyZoomAnim, this);
	},

	_unspiderfyZoomAnim: function (zoomDetails) {
		//Wait until the first zoomanim after the user has finished touch-zooming before running the animation
		if (L.DomUtil.hasClass(this._map._mapPane, 'leaflet-touching')) {
			return;
		}

		this._map.off('zoomanim', this._unspiderfyZoomAnim, this);
		this._unspiderfy(zoomDetails);
	},

	_unspiderfyWrapper: function () {
		/// <summary>_unspiderfy but passes no arguments</summary>
		this._unspiderfy();
	},

	_unspiderfy: function (zoomDetails) {
		if (this._spiderfied) {
			this._spiderfied.unspiderfy(zoomDetails);
		}
	},

	_noanimationUnspiderfy: function () {
		if (this._spiderfied) {
			this._spiderfied._noanimationUnspiderfy();
		}
	},

	//If the given layer is currently being spiderfied then we unspiderfy it so it isn't on the map anymore etc
	_unspiderfyLayer: function (layer) {
		if (layer._spiderLeg) {
			this._featureGroup.removeLayer(layer);

			if (layer.clusterShow) {
				layer.clusterShow();
			}
				//Position will be fixed up immediately in _animationUnspiderfy
			if (layer.setZIndexOffset) {
				layer.setZIndexOffset(0);
			}

			this._map.removeLayer(layer._spiderLeg);
			delete layer._spiderLeg;
		}
	}
});