Adding paging and cluster strategies. The paging strategy intercepts a batch of features bound for the layer and caches them, giving the layer one page at a time. The cluster strategy intercepts a batch of features and groups proximate features as clusters - giving the clusters to the layer instead. Thanks for the careful review Erik. r=euzuro (see #1606).
git-svn-id: http://svn.openlayers.org/trunk/openlayers@8003 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Tim Schaub
241
lib/OpenLayers/Strategy/Paging.js
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241
lib/OpenLayers/Strategy/Paging.js
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/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
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* license. See http://svn.openlayers.org/trunk/openlayers/license.txt for the
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* full text of the license. */
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/**
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* @requires OpenLayers/Strategy.js
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*/
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/**
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* Class: OpenLayers.Strategy.Paging
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* Strategy for vector feature paging
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*
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* Inherits from:
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* - <OpenLayers.Strategy>
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*/
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OpenLayers.Strategy.Paging = OpenLayers.Class(OpenLayers.Strategy, {
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/**
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* Property: layer
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* {<OpenLayers.Layer.Vector>} The layer that this strategy is assigned to.
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*/
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layer: null,
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/**
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* Property: features
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* {Array(<OpenLayers.Feature.Vector>)} Cached features.
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*/
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features: null,
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/**
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* Property: length
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* {Integer} Number of features per page. Default is 10.
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*/
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length: 10,
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/**
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* Property: num
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* {Integer} The currently displayed page number.
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*/
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num: null,
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/**
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* Property: paging
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* {Boolean} The strategy is currently changing pages.
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*/
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paging: false,
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/**
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* Constructor: OpenLayers.Strategy.Paging
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* Create a new paging strategy.
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*
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* Parameters:
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* options - {Object} Optional object whose properties will be set on the
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* instance.
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*/
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initialize: function(options) {
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OpenLayers.Strategy.prototype.initialize.apply(this, [options]);
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},
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/**
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* APIMethod: activate
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* Activate the strategy. Register any listeners, do appropriate setup.
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*
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* Returns:
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* {Boolean} The strategy was successfully activated.
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*/
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activate: function() {
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var activated = OpenLayers.Strategy.prototype.activate.call(this);
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if(activated) {
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this.layer.events.on({
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"beforefeaturesadded": this.cacheFeatures,
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scope: this
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});
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}
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return activated;
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},
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/**
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* APIMethod: deactivate
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* Deactivate the strategy. Unregister any listeners, do appropriate
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* tear-down.
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*
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* Returns:
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* {Boolean} The strategy was successfully deactivated.
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*/
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deactivate: function() {
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var deactivated = OpenLayers.Strategy.prototype.deactivate.call(this);
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if(deactivated) {
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this.clearCache();
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this.layer.events.un({
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"beforefeaturesadded": this.cacheFeatures,
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scope: this
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});
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}
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return deactivated;
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},
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/**
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* Method: cacheFeatures
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* Cache features before they are added to the layer.
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*
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* Parameters:
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* event - {Object} The event that this was listening for. This will come
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* with a batch of features to be paged.
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*/
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cacheFeatures: function(event) {
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if(!this.paging) {
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this.clearCache();
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this.features = event.features;
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this.pageNext(event);
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}
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},
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/**
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* Method: clearCache
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* Clear out the cached features. This destroys features, assuming
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* nothing else has a reference.
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*/
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clearCache: function() {
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if(this.features) {
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for(var i=0; i<this.features.length; ++i) {
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this.features[i].destroy();
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}
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}
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this.features = null;
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this.num = null;
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},
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/**
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* APIMethod: pageCount
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* Get the total count of pages given the current cache of features.
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*
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* Returns:
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* {Integer} The page count.
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*/
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pageCount: function() {
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var numFeatures = this.features ? this.features.length : 0;
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return Math.ceil(numFeatures / this.length);
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},
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/**
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* APIMethod: pageNum
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* Get the zero based page number.
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*
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* Returns:
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* {Integer} The current page number being displayed.
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*/
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pageNum: function() {
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return this.num;
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},
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/**
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* APIMethod: pageLength
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* Gets or sets page length.
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*
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* Parameters:
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* newLength: {Integer} Optional length to be set.
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*
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* Returns:
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* {Integer} The length of a page (number of features per page).
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*/
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pageLength: function(newLength) {
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if(newLength && newLength > 0) {
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this.length = newLength;
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}
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return this.length;
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},
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/**
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* APIMethod: pageNext
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* Display the next page of features.
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*
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* Returns:
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* {Boolean} A new page was displayed.
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*/
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pageNext: function(event) {
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var changed = false;
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if(this.features) {
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if(this.num === null) {
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this.num = -1;
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}
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var start = (this.num + 1) * this.length;
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changed = this.page(start, event);
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}
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return changed;
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},
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/**
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* APIMethod: pagePrevious
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* Display the previous page of features.
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*
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* Returns:
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* {Boolean} A new page was displayed.
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*/
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pagePrevious: function() {
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var changed = false;
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if(this.features) {
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if(this.num === null) {
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this.num = this.pageCount();
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}
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var start = (this.num - 1) * this.length;
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changed = this.page(start);
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}
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return changed;
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},
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/**
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* Method: page
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* Display the page starting at the given index from the cache.
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*
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* Returns:
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* {Boolean} A new page was displayed.
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*/
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page: function(start, event) {
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var changed = false;
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if(this.features) {
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if(start >= 0 && start < this.features.length) {
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var num = Math.floor(start / this.length);
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if(num != this.num) {
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this.paging = true;
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var features = this.features.slice(start, start + this.length);
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this.layer.removeFeatures(this.layer.features);
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this.num = num;
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// modify the event if any
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if(event && event.features) {
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// this.was called by an event listener
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event.features = features;
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} else {
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// this was called directly on the strategy
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this.layer.addFeatures(features);
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}
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this.paging = false;
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changed = true;
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}
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}
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}
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return changed;
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},
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CLASS_NAME: "OpenLayers.Strategy.Paging"
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});
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