[76] | 1 | /* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for |
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| 2 | * full list of contributors). Published under the Clear BSD license. |
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| 3 | * See http://svn.openlayers.org/trunk/openlayers/license.txt for the |
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| 4 | * full text of the license. */ |
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| 5 | |
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| 6 | /** |
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| 7 | * @requires OpenLayers/Strategy.js |
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| 8 | */ |
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| 9 | |
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| 10 | /** |
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| 11 | * Class: OpenLayers.Strategy.Paging |
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| 12 | * Strategy for vector feature paging |
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| 13 | * |
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| 14 | * Inherits from: |
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| 15 | * - <OpenLayers.Strategy> |
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| 16 | */ |
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| 17 | OpenLayers.Strategy.Paging = OpenLayers.Class(OpenLayers.Strategy, { |
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| 18 | |
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| 19 | /** |
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| 20 | * Property: features |
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| 21 | * {Array(<OpenLayers.Feature.Vector>)} Cached features. |
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| 22 | */ |
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| 23 | features: null, |
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| 24 | |
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| 25 | /** |
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| 26 | * Property: length |
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| 27 | * {Integer} Number of features per page. Default is 10. |
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| 28 | */ |
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| 29 | length: 10, |
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| 30 | |
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| 31 | /** |
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| 32 | * Property: num |
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| 33 | * {Integer} The currently displayed page number. |
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| 34 | */ |
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| 35 | num: null, |
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| 36 | |
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| 37 | /** |
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| 38 | * Property: paging |
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| 39 | * {Boolean} The strategy is currently changing pages. |
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| 40 | */ |
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| 41 | paging: false, |
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| 42 | |
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| 43 | /** |
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| 44 | * Constructor: OpenLayers.Strategy.Paging |
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| 45 | * Create a new paging strategy. |
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| 46 | * |
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| 47 | * Parameters: |
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| 48 | * options - {Object} Optional object whose properties will be set on the |
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| 49 | * instance. |
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| 50 | */ |
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| 51 | initialize: function(options) { |
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| 52 | OpenLayers.Strategy.prototype.initialize.apply(this, [options]); |
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| 53 | }, |
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| 54 | |
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| 55 | /** |
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| 56 | * APIMethod: activate |
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| 57 | * Activate the strategy. Register any listeners, do appropriate setup. |
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| 58 | * |
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| 59 | * Returns: |
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| 60 | * {Boolean} The strategy was successfully activated. |
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| 61 | */ |
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| 62 | activate: function() { |
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| 63 | var activated = OpenLayers.Strategy.prototype.activate.call(this); |
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| 64 | if(activated) { |
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| 65 | this.layer.events.on({ |
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| 66 | "beforefeaturesadded": this.cacheFeatures, |
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| 67 | scope: this |
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| 68 | }); |
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| 69 | } |
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| 70 | return activated; |
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| 71 | }, |
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| 72 | |
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| 73 | /** |
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| 74 | * APIMethod: deactivate |
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| 75 | * Deactivate the strategy. Unregister any listeners, do appropriate |
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| 76 | * tear-down. |
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| 77 | * |
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| 78 | * Returns: |
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| 79 | * {Boolean} The strategy was successfully deactivated. |
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| 80 | */ |
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| 81 | deactivate: function() { |
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| 82 | var deactivated = OpenLayers.Strategy.prototype.deactivate.call(this); |
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| 83 | if(deactivated) { |
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| 84 | this.clearCache(); |
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| 85 | this.layer.events.un({ |
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| 86 | "beforefeaturesadded": this.cacheFeatures, |
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| 87 | scope: this |
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| 88 | }); |
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| 89 | } |
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| 90 | return deactivated; |
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| 91 | }, |
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| 92 | |
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| 93 | /** |
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| 94 | * Method: cacheFeatures |
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| 95 | * Cache features before they are added to the layer. |
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| 96 | * |
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| 97 | * Parameters: |
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| 98 | * event - {Object} The event that this was listening for. This will come |
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| 99 | * with a batch of features to be paged. |
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| 100 | */ |
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| 101 | cacheFeatures: function(event) { |
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| 102 | if(!this.paging) { |
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| 103 | this.clearCache(); |
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| 104 | this.features = event.features; |
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| 105 | this.pageNext(event); |
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| 106 | } |
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| 107 | }, |
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| 108 | |
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| 109 | /** |
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| 110 | * Method: clearCache |
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| 111 | * Clear out the cached features. This destroys features, assuming |
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| 112 | * nothing else has a reference. |
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| 113 | */ |
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| 114 | clearCache: function() { |
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| 115 | if(this.features) { |
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| 116 | for(var i=0; i<this.features.length; ++i) { |
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| 117 | this.features[i].destroy(); |
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| 118 | } |
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| 119 | } |
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| 120 | this.features = null; |
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| 121 | this.num = null; |
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| 122 | }, |
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| 123 | |
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| 124 | /** |
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| 125 | * APIMethod: pageCount |
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| 126 | * Get the total count of pages given the current cache of features. |
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| 127 | * |
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| 128 | * Returns: |
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| 129 | * {Integer} The page count. |
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| 130 | */ |
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| 131 | pageCount: function() { |
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| 132 | var numFeatures = this.features ? this.features.length : 0; |
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| 133 | return Math.ceil(numFeatures / this.length); |
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| 134 | }, |
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| 135 | |
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| 136 | /** |
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| 137 | * APIMethod: pageNum |
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| 138 | * Get the zero based page number. |
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| 139 | * |
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| 140 | * Returns: |
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| 141 | * {Integer} The current page number being displayed. |
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| 142 | */ |
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| 143 | pageNum: function() { |
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| 144 | return this.num; |
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| 145 | }, |
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| 146 | |
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| 147 | /** |
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| 148 | * APIMethod: pageLength |
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| 149 | * Gets or sets page length. |
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| 150 | * |
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| 151 | * Parameters: |
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| 152 | * newLength: {Integer} Optional length to be set. |
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| 153 | * |
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| 154 | * Returns: |
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| 155 | * {Integer} The length of a page (number of features per page). |
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| 156 | */ |
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| 157 | pageLength: function(newLength) { |
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| 158 | if(newLength && newLength > 0) { |
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| 159 | this.length = newLength; |
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| 160 | } |
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| 161 | return this.length; |
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| 162 | }, |
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| 163 | |
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| 164 | /** |
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| 165 | * APIMethod: pageNext |
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| 166 | * Display the next page of features. |
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| 167 | * |
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| 168 | * Returns: |
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| 169 | * {Boolean} A new page was displayed. |
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| 170 | */ |
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| 171 | pageNext: function(event) { |
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| 172 | var changed = false; |
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| 173 | if(this.features) { |
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| 174 | if(this.num === null) { |
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| 175 | this.num = -1; |
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| 176 | } |
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| 177 | var start = (this.num + 1) * this.length; |
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| 178 | changed = this.page(start, event); |
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| 179 | } |
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| 180 | return changed; |
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| 181 | }, |
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| 182 | |
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| 183 | /** |
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| 184 | * APIMethod: pagePrevious |
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| 185 | * Display the previous page of features. |
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| 186 | * |
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| 187 | * Returns: |
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| 188 | * {Boolean} A new page was displayed. |
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| 189 | */ |
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| 190 | pagePrevious: function() { |
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| 191 | var changed = false; |
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| 192 | if(this.features) { |
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| 193 | if(this.num === null) { |
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| 194 | this.num = this.pageCount(); |
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| 195 | } |
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| 196 | var start = (this.num - 1) * this.length; |
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| 197 | changed = this.page(start); |
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| 198 | } |
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| 199 | return changed; |
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| 200 | }, |
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| 201 | |
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| 202 | /** |
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| 203 | * Method: page |
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| 204 | * Display the page starting at the given index from the cache. |
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| 205 | * |
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| 206 | * Returns: |
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| 207 | * {Boolean} A new page was displayed. |
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| 208 | */ |
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| 209 | page: function(start, event) { |
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| 210 | var changed = false; |
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| 211 | if(this.features) { |
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| 212 | if(start >= 0 && start < this.features.length) { |
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| 213 | var num = Math.floor(start / this.length); |
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| 214 | if(num != this.num) { |
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| 215 | this.paging = true; |
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| 216 | var features = this.features.slice(start, start + this.length); |
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| 217 | this.layer.removeFeatures(this.layer.features); |
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| 218 | this.num = num; |
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| 219 | // modify the event if any |
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| 220 | if(event && event.features) { |
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| 221 | // this.was called by an event listener |
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| 222 | event.features = features; |
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| 223 | } else { |
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| 224 | // this was called directly on the strategy |
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| 225 | this.layer.addFeatures(features); |
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| 226 | } |
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| 227 | this.paging = false; |
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| 228 | changed = true; |
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| 229 | } |
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| 230 | } |
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| 231 | } |
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| 232 | return changed; |
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| 233 | }, |
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| 234 | |
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| 235 | CLASS_NAME: "OpenLayers.Strategy.Paging" |
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| 236 | }); |
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