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/*
* L.Handler.ScrollWheelZoom is used internally by L.Map to enable mouse scroll wheel zooming on the map.
*/
L.Handler.ScrollWheelZoom = L.Handler.extend({
enable: function() {
if (this._enabled) { return; }
L.DomEvent.addListener(this._map._container, 'mousewheel', this._onWheelScroll, this);
this._delta = 0;
this._enabled = true;
},
disable: function() {
if (!this._enabled) { return; }
L.DomEvent.removeListener(this._map._container, 'mousewheel', this._onWheelScroll);
this._enabled = false;
},
_onWheelScroll: function(e) {
this._delta += L.DomEvent.getWheelDelta(e);
this._lastMousePos = this._map.mouseEventToContainerPoint(e);
clearTimeout(this._timer);
this._timer = setTimeout(L.Util.bind(this._performZoom, this), 50);
L.DomEvent.preventDefault(e);
},
_performZoom: function() {
var delta = Math.round(this._delta);
this._delta = 0;
if (!delta) { return; }
var center = this._getCenterForScrollWheelZoom(this._lastMousePos, delta),
zoom = this._map.getZoom() + delta;
if (this._map._limitZoom(zoom) == this._map._zoom) { return; }
this._map.setView(center, zoom);
},
_getCenterForScrollWheelZoom: function(mousePos, delta) {
var centerPoint = this._map.getPixelBounds().getCenter(),
viewHalf = this._map.getSize().divideBy(2),
centerOffset = mousePos.subtract(viewHalf).multiplyBy(1 - Math.pow(2, -delta)),
newCenterPoint = centerPoint.add(centerOffset);
return this._map.unproject(newCenterPoint, this._map._zoom, true);
}
});
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