0ba7961df4
improvements in the form of reduced memory use and lower element creating costs, hopefully making the OpenLayers code more usable in internet explorer as well as less of a memory hog in Firefox and other browsers. Additionally, a buffer is available around the main map grid which allows tiles to be loaded outside of the viewing area for faster dragging. git-svn-id: http://svn.openlayers.org/trunk/openlayers@1137 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
340 lines
9.2 KiB
JavaScript
340 lines
9.2 KiB
JavaScript
/* Copyright (c) 2006 MetaCarta, Inc., published under the BSD license.
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* See http://svn.openlayers.org/trunk/openlayers/license.txt for the full
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* text of the license. */
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/**
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* @class
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*/
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OpenLayers.Layer = Class.create();
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OpenLayers.Layer.prototype = {
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/** @type String */
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id: null,
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/** @type String */
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name: null,
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/** @type DOMElement */
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div: null,
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/** This variable is set when the layer is added to the map, via the
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* accessor function setMap()
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*
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* @type OpenLayers.Map */
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map: null,
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/** Whether or not the layer is a base layer. This should be set
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* individually by all subclasses.
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* Default is false
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*
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* @type Boolean
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*/
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isBaseLayer: false,
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/** asserts whether or not the layer's images have an alpha channel
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*
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* @type boolean */
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alpha: false,
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// OPTIONS
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/** @type Array */
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options: null,
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/** @type String */
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projection: null,
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/** @type OpenLayers.Bounds */
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maxExtent: null,
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/** @type float */
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maxResolution: null,
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/** @type int */
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minZoomLevel: null,
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/** @type int */
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maxZoomLevel: null,
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/**
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* @constructor
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*
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* @param {String} name
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* @param {Object} options Hash of extra options to tag onto the layer
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*/
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initialize: function(name, options) {
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if (arguments.length > 0) {
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//store a copy of the custom options for later cloning
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this.options = Object.extend(new Object(), options);
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//add options to layer
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Object.extend(this, this.options);
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this.name = name;
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//generate unique id based on name
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this.id = OpenLayers.Util.createUniqueID("Layer_");
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if (this.div == null) {
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this.div = OpenLayers.Util.createDiv();
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this.div.style.width = "100%";
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this.div.style.height = "100%";
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}
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}
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},
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/**
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* Destroy is a destructor: this is to alleviate cyclic references which
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* the Javascript garbage cleaner can not take care of on its own.
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*/
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destroy: function() {
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if (this.map != null) {
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this.map.removeLayer(this);
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}
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this.map = null;
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this.name = null;
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this.div = null;
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this.options = null;
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},
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/**
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* @returns An exact clone of this OpenLayers.Layer
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* @type OpenLayers.Layer
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*/
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clone: function (obj) {
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if (obj == null) {
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obj = new OpenLayers.Layer(this.name, this.options);
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}
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// catch any randomly tagged-on properties
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obj = OpenLayers.Util.applyDefaults(obj, this);
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// a cloned layer should never have its map property set
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// because it has not been added to a map yet.
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obj.map = null;
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return obj;
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},
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/**
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* @param {String} newName
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*/
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setName: function(newName) {
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this.name = newName;
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},
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/**
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* @param {Hash} newOptions
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*/
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addOptions: function (newOptions) {
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// update our copy for clone
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Object.extend(this.options, newOptions);
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// add new options to this
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Object.extend(this, this.options);
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},
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/**
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* @param {OpenLayers.Bounds} bound
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* @param {Boolean} zoomChanged tells when zoom has changed, as layers
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* have to do some init work in that case.
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* @param {Boolean} minor
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*/
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moveTo:function(bounds, zoomChanged, minor) {
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//this function can be implemented by subclasses.
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},
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/**
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*/
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reproject:function() {
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//this function can be implemented by subclasses.
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},
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/** Set the map property for the layer. This is done through an accessor
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* so that subclasses can override this and take special action once
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* they have their map variable set.
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*
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* @param {OpenLayers.Map} map
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*/
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setMap: function(map) {
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this.map = map;
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},
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/**
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* @returns Whether or not the layer is visible
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* @type Boolean
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*/
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getVisibility: function() {
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return (this.div.style.display != "none");
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},
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/**
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* @param {Boolean} visible
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* @param {Boolean} noEvent
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*/
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setVisibility: function(visible, noEvent) {
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if (visible != this.getVisibility()) {
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this.div.style.display = (visible) ? "block" : "none";
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if ((visible) && (this.map != null)) {
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var extent = this.map.getExtent();
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if (extent != null) {
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this.moveTo(this.map.getExtent());
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}
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}
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if ((this.map != null) &&
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((noEvent == null) || (noEvent == false))) {
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this.map.events.triggerEvent("changelayer");
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}
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}
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},
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/********************************************************/
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/* */
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/* Layer Options */
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/* */
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/* Accessor functions to Layer Options parameters */
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/* */
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/********************************************************/
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/**
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* @type String
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*/
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getProjection: function() {
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return this.projection;
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},
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/**
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* @type OpenLayers.Bounds
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*/
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getMaxExtent: function() {
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return this.maxExtent;
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},
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/**
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* @type float
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*/
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getMaxResolution: function() {
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return this.maxResolution;
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},
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/**
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* @returns The minimum zoom level that can be reached in this layer
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* @type int
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*/
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getMinZoomLevel: function() {
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return this.minZoomLevel;
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},
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/**
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* @returns The maximum zoom level that can be reached in this layer
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* @type int
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*/
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getMaxZoomLevel: function() {
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return this.maxZoomLevel;
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},
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/********************************************************/
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/* */
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/* Baselayer Functions */
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/* */
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/* The following functions must all be implemented */
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/* by all base layers */
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/* */
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/********************************************************/
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/**
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* @returns Degrees per Pixel
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* @type float
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*/
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getResolution: function() {
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var viewSize = this.map.getSize();
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var extent = this.map.getExtent();
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return Math.max( extent.getWidth() / viewSize.w,
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extent.getHeight() / viewSize.h );
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},
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/** Calculates using px-> lonlat translation functions on tl and br
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* corners of viewport
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*
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* @returns A Bounds object which represents the lon/lat bounds of the
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* current viewPort.
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* @type OpenLayers.Bounds
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*/
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getExtent: function () {
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var extent = null;
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var size = this.map.getSize();
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var tlPx = new OpenLayers.Pixel(0,0);
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var tlLL = this.getLonLatFromViewPortPx(tlPx);
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var brPx = new OpenLayers.Pixel(size.w, size.h);
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var brLL = this.getLonLatFromViewPortPx(brPx);
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if ((tlLL != null) && (brLL != null)) {
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extent = new OpenLayers.Bounds(tlLL.lon,
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brLL.lat,
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brLL.lon,
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tlLL.lat);
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}
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return extent;
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},
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/**
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* @param {OpenLayers.Pixel} viewPortPx
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*
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* @returns An OpenLayers.LonLat which is the passed-in view port
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* OpenLayers.Pixel, translated into lon/lat by the layer
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* @type OpenLayers.LonLat
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*/
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getLonLatFromViewPortPx: function (viewPortPx) {
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var size = this.map.getSize();
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var center = this.map.getCenter(); //map center lon/lat
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var res = this.map.getResolution();
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var delta_x = viewPortPx.x - (size.w / 2);
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var delta_y = viewPortPx.y - (size.h / 2);
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return new OpenLayers.LonLat(center.lon + delta_x * res ,
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center.lat - delta_y * res);
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},
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/**
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* @param {OpenLayers.LonLat} lonlat
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*
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* @returns An OpenLayers.Pixel which is the passed-in OpenLayers.LonLat,
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* translated into view port pixels
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* @type OpenLayers.Pixel
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*/
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getViewPortPxFromLonLat: function (lonlat) {
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var resolution = this.map.getResolution();
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var extent = this.map.getExtent();
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return new OpenLayers.Pixel(
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Math.round(1/resolution * (lonlat.lon - extent.left)),
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Math.round(1/resolution * (extent.top - lonlat.lat))
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);
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},
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/**
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* @param {OpenLayers.Bounds} bounds
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*
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* @return {int}
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*/
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getZoomForExtent: function (bounds) {
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// this should be implemented by subclasses
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},
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/** @final @type String */
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CLASS_NAME: "OpenLayers.Layer"
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};
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