/*
* L.Handler.ScrollWheelZoom is used by L.Map to enable mouse scroll wheel zoom on the map.
*/
L.Map.mergeOptions({
scrollWheelZoom: true
});
L.Map.ScrollWheelZoom = L.Handler.extend({
addHooks: function () {
L.DomEvent.on(this._map._container, 'mousewheel', this._onWheelScroll, this);
this._delta = 0;
},
removeHooks: function () {
L.DomEvent.off(this._map._container, 'mousewheel', this._onWheelScroll);
},
_onWheelScroll: function (e) {
var delta = L.DomEvent.getWheelDelta(e);
this._delta += delta;
this._lastMousePos = this._map.mouseEventToContainerPoint(e);
if (!this._startTime) {
this._startTime = +new Date();
}
var left = Math.max(40 - (+new Date() - this._startTime), 0);
clearTimeout(this._timer);
this._timer = setTimeout(L.bind(this._performZoom, this), left);
L.DomEvent.preventDefault(e);
L.DomEvent.stopPropagation(e);
},
_performZoom: function () {
var map = this._map,
delta = this._delta,
zoom = map.getZoom();
delta = delta > 0 ? Math.ceil(delta) : Math.round(delta);
delta = Math.max(Math.min(delta, 4), -4);
delta = map._limitZoom(zoom + delta) - zoom;
this._delta = 0;
this._startTime = null;
if (!delta) { return; }
var newZoom = zoom + delta,
newCenter = this._getCenterForScrollWheelZoom(newZoom);
map.setView(newCenter, newZoom);
},
_getCenterForScrollWheelZoom: function (newZoom) {
var map = this._map,
scale = map.getZoomScale(newZoom),
viewHalf = map.getSize()._divideBy(2),
centerOffset = this._lastMousePos._subtract(viewHalf)._multiplyBy(1 - 1 / scale),
newCenterPoint = map._getTopLeftPoint()._add(viewHalf)._add(centerOffset);
return map.unproject(newCenterPoint);
}
});
L.Map.addInitHook('addHandler', 'scrollWheelZoom', L.Map.ScrollWheelZoom);
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