75 lines
1.9 KiB
JavaScript
75 lines
1.9 KiB
JavaScript
/**
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* @fileoverview Mouse Wheel Handler.
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*
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* Provides a class for listening to mousewheel events on a DOM element
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* and re-dispatching to a map instance.
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*
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* The default behabior is zooming the map.
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*/
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goog.provide('ol.handler.MouseWheel');
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goog.require('goog.asserts');
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goog.require('goog.events');
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goog.require('goog.style');
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goog.require('goog.Disposable');
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goog.require('goog.events.MouseWheelHandler');
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goog.require('goog.events.MouseWheelHandler.EventType');
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/**
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* @constructor
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* @extends {goog.Disposable}
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* @param {ol.Map} map The map instance.
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* @param {Element} elt The element we listen to mousewheel on.
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* @param {Object} states An object for the handlers to share states.
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*/
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ol.handler.MouseWheel = function(map, elt, states) {
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goog.base(this);
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var handler = new goog.events.MouseWheelHandler(elt);
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this.registerDisposable(handler);
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/**
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* @param {goog.events.MouseWheelEvent} e
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*/
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goog.events.listen(handler,
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goog.events.MouseWheelHandler.EventType.MOUSEWHEEL,
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this.handleMouseWheel, false, this);
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};
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goog.inherits(ol.handler.MouseWheel, goog.Disposable);
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/**
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* @param {goog.events.MouseWheelEvent} e
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*/
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ol.handler.MouseWheel.prototype.handleMouseWheel = function(e) {
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e.position = goog.style.getRelativePosition(e, this.elt_);
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e.type = 'mousewheel';
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var rt = goog.events.dispatchEvent(this.map_, e);
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if (rt) {
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this.defaultBehavior(e);
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}
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};
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/**
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* @param {goog.events.MouseWheelEvent} e
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*/
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ol.handler.MouseWheel.prototype.defaultBehavior = function(e) {
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var me = this;
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if (e.deltaY === 0 || me.zoomBlocked_) {
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return;
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}
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me.zoomBlocked_ = window.setTimeout(function() {
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me.zoomBlocked_ = null;
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}, 200);
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var map = me.map_,
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step = e.deltaY / Math.abs(e.deltaY);
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map.setZoom(map.getZoom() - step, e.position);
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// We don't want the page to scroll.
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e.preventDefault();
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};
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