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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
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* full list of contributors). Published under the 2-clause BSD license.
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* See license.txt in the OpenLayers distribution or repository for the
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* full text of the license. */
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/**
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* @requires OpenLayers/Util.js
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* @requires OpenLayers/BaseTypes.js
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* @requires OpenLayers/BaseTypes/Element.js
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* @requires OpenLayers/Layer/Grid.js
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* @requires OpenLayers/Tile/Image.js
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*/
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/**
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* Class: OpenLayers.TileManager
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* Provides queueing of image requests and caching of image elements.
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*
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* Queueing avoids unnecessary image requests while changing zoom levels
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* quickly, and helps improve dragging performance on mobile devices that show
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* a lag in dragging when loading of new images starts. <zoomDelay> and
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* <moveDelay> are the configuration options to control this behavior.
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*
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* Caching avoids setting the src on image elements for images that have already
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* been used. Several maps can share a TileManager instance, in which case each
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* map gets its own tile queue, but all maps share the same tile cache.
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*/
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OpenLayers.TileManager = OpenLayers.Class({
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/**
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* APIProperty: cacheSize
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* {Number} Number of image elements to keep referenced in this instance's
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* cache for fast reuse. Default is 256.
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*/
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cacheSize: 256,
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/**
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* APIProperty: tilesPerFrame
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* {Number} Number of queued tiles to load per frame (see <frameDelay>).
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* Default is 2.
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*/
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tilesPerFrame: 2,
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/**
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* APIProperty: frameDelay
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* {Number} Delay between tile loading frames (see <tilesPerFrame>) in
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* milliseconds. Default is 16.
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*/
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frameDelay: 16,
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/**
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* APIProperty: moveDelay
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* {Number} Delay in milliseconds after a map's move event before loading
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* tiles. Default is 100.
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*/
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moveDelay: 100,
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/**
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* APIProperty: zoomDelay
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* {Number} Delay in milliseconds after a map's zoomend event before loading
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* tiles. Default is 200.
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*/
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zoomDelay: 200,
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/**
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* Property: maps
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* {Array(<OpenLayers.Map>)} The maps to manage tiles on.
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*/
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maps: null,
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/**
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* Property: tileQueueId
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* {Object} The ids of the <drawTilesFromQueue> loop, keyed by map id.
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*/
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tileQueueId: null,
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/**
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* Property: tileQueue
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* {Object(Array(<OpenLayers.Tile>))} Tiles queued for drawing, keyed by
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* map id.
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*/
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tileQueue: null,
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/**
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* Property: tileCache
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* {Object} Cached image elements, keyed by URL.
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*/
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tileCache: null,
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/**
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* Property: tileCacheIndex
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* {Array(String)} URLs of cached tiles. First entry is the least recently
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* used.
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*/
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tileCacheIndex: null,
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/**
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* Constructor: OpenLayers.TileManager
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* Constructor for a new <OpenLayers.TileManager> instance.
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*
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* Parameters:
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* options - {Object} Configuration for this instance.
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*/
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initialize: function(options) {
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OpenLayers.Util.extend(this, options);
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this.maps = [];
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this.tileQueueId = {};
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this.tileQueue = {};
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this.tileCache = {};
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this.tileCacheIndex = [];
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},
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/**
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* Method: addMap
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* Binds this instance to a map
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*
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* Parameters:
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* map - {<OpenLayers.Map>}
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*/
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addMap: function(map) {
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if (this._destroyed || !OpenLayers.Layer.Grid) {
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return;
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}
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this.maps.push(map);
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this.tileQueue[map.id] = [];
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for (var i=0, ii=map.layers.length; i<ii; ++i) {
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this.addLayer({layer: map.layers[i]});
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}
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map.events.on({
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move: this.move,
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zoomend: this.zoomEnd,
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changelayer: this.changeLayer,
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addlayer: this.addLayer,
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preremovelayer: this.removeLayer,
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scope: this
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});
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},
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/**
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* Method: removeMap
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* Unbinds this instance from a map
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*
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* Parameters:
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* map - {<OpenLayers.Map>}
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*/
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removeMap: function(map) {
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if (this._destroyed || !OpenLayers.Layer.Grid) {
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return;
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}
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window.clearTimeout(this.tileQueueId[map.id]);
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if (map.layers) {
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for (var i=0, ii=map.layers.length; i<ii; ++i) {
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this.removeLayer({layer: map.layers[i]});
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}
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}
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if (map.events) {
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map.events.un({
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move: this.move,
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zoomend: this.zoomEnd,
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changelayer: this.changeLayer,
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addlayer: this.addLayer,
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preremovelayer: this.removeLayer,
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scope: this
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});
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}
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delete this.tileQueue[map.id];
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delete this.tileQueueId[map.id];
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OpenLayers.Util.removeItem(this.maps, map);
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},
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/**
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* Method: move
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* Handles the map's move event
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*
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* Parameters:
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* evt - {Object} Listener argument
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*/
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move: function(evt) {
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this.updateTimeout(evt.object, this.moveDelay, true);
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},
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/**
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* Method: zoomEnd
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* Handles the map's zoomEnd event
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*
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* Parameters:
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* evt - {Object} Listener argument
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*/
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zoomEnd: function(evt) {
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this.updateTimeout(evt.object, this.zoomDelay);
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},
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/**
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* Method: changeLayer
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* Handles the map's changeLayer event
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*
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* Parameters:
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* evt - {Object} Listener argument
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*/
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changeLayer: function(evt) {
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if (evt.property === 'visibility' || evt.property === 'params') {
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this.updateTimeout(evt.object, 0);
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}
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},
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/**
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* Method: addLayer
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* Handles the map's addlayer event
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*
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* Parameters:
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* evt - {Object} The listener argument
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*/
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addLayer: function(evt) {
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var layer = evt.layer;
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if (layer instanceof OpenLayers.Layer.Grid) {
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layer.events.on({
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addtile: this.addTile,
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retile: this.clearTileQueue,
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scope: this
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});
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var i, j, tile;
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for (i=layer.grid.length-1; i>=0; --i) {
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for (j=layer.grid[i].length-1; j>=0; --j) {
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tile = layer.grid[i][j];
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this.addTile({tile: tile});
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if (tile.url && !tile.imgDiv) {
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this.manageTileCache({object: tile});
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}
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}
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}
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}
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},
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/**
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* Method: removeLayer
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* Handles the map's preremovelayer event
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*
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* Parameters:
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* evt - {Object} The listener argument
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*/
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removeLayer: function(evt) {
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var layer = evt.layer;
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if (layer instanceof OpenLayers.Layer.Grid) {
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this.clearTileQueue({object: layer});
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if (layer.events) {
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layer.events.un({
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addtile: this.addTile,
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retile: this.clearTileQueue,
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scope: this
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});
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}
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if (layer.grid) {
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var i, j, tile;
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for (i=layer.grid.length-1; i>=0; --i) {
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for (j=layer.grid[i].length-1; j>=0; --j) {
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tile = layer.grid[i][j];
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this.unloadTile({object: tile});
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}
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}
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}
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}
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},
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/**
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* Method: updateTimeout
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* Applies the <moveDelay> or <zoomDelay> to the <drawTilesFromQueue> loop,
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* and schedules more queue processing after <frameDelay> if there are still
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* tiles in the queue.
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*
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* Parameters:
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* map - {<OpenLayers.Map>} The map to update the timeout for
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* delay - {Number} The delay to apply
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* nice - {Boolean} If true, the timeout function will only be created if
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* the tilequeue is not empty. This is used by the move handler to
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* avoid impacts on dragging performance. For other events, the tile
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* queue may not be populated yet, so we need to set the timer
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* regardless of the queue size.
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*/
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updateTimeout: function(map, delay, nice) {
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window.clearTimeout(this.tileQueueId[map.id]);
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var tileQueue = this.tileQueue[map.id];
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if (!nice || tileQueue.length) {
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this.tileQueueId[map.id] = window.setTimeout(
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OpenLayers.Function.bind(function() {
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this.drawTilesFromQueue(map);
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if (tileQueue.length) {
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this.updateTimeout(map, this.frameDelay);
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}
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}, this), delay
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);
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}
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},
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/**
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* Method: addTile
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* Listener for the layer's addtile event
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*
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* Parameters:
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* evt - {Object} The listener argument
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*/
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addTile: function(evt) {
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if (evt.tile instanceof OpenLayers.Tile.Image) {
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evt.tile.events.on({
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beforedraw: this.queueTileDraw,
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beforeload: this.manageTileCache,
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loadend: this.addToCache,
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unload: this.unloadTile,
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scope: this
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});
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} else {
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// Layer has the wrong tile type, so don't handle it any longer
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this.removeLayer({layer: evt.tile.layer});
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}
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},
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/**
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* Method: unloadTile
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* Listener for the tile's unload event
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*
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* Parameters:
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* evt - {Object} The listener argument
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*/
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unloadTile: function(evt) {
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var tile = evt.object;
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tile.events.un({
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beforedraw: this.queueTileDraw,
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beforeload: this.manageTileCache,
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loadend: this.addToCache,
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unload: this.unloadTile,
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scope: this
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});
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OpenLayers.Util.removeItem(this.tileQueue[tile.layer.map.id], tile);
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},
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/**
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* Method: queueTileDraw
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* Adds a tile to the queue that will draw it.
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*
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* Parameters:
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* evt - {Object} Listener argument of the tile's beforedraw event
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*/
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queueTileDraw: function(evt) {
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var tile = evt.object;
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var queued = false;
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var layer = tile.layer;
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var url = layer.getURL(tile.bounds);
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var img = this.tileCache[url];
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if (img && img.className !== 'olTileImage') {
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// cached image no longer valid, e.g. because we're olTileReplacing
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delete this.tileCache[url];
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OpenLayers.Util.removeItem(this.tileCacheIndex, url);
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img = null;
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}
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// queue only if image with same url not cached already
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if (layer.url && (layer.async || !img)) {
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// add to queue only if not in queue already
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var tileQueue = this.tileQueue[layer.map.id];
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if (!~OpenLayers.Util.indexOf(tileQueue, tile)) {
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tileQueue.push(tile);
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}
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queued = true;
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}
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return !queued;
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},
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365
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366
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/**
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* Method: drawTilesFromQueue
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* Draws tiles from the tileQueue, and unqueues the tiles
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*/
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drawTilesFromQueue: function(map) {
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var tileQueue = this.tileQueue[map.id];
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var limit = this.tilesPerFrame;
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var animating = map.zoomTween && map.zoomTween.playing;
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while (!animating && tileQueue.length && limit) {
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tileQueue.shift().draw(true);
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--limit;
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}
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},
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379
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380
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/**
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* Method: manageTileCache
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382
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* Adds, updates, removes and fetches cache entries.
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383
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*
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384
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* Parameters:
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385
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* evt - {Object} Listener argument of the tile's beforeload event
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386
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*/
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387
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manageTileCache: function(evt) {
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var tile = evt.object;
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389
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var img = this.tileCache[tile.url];
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390
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if (img) {
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391
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// if image is on its layer's backbuffer, remove it from backbuffer
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392
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if (img.parentNode &&
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393
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OpenLayers.Element.hasClass(img.parentNode, 'olBackBuffer')) {
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394
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img.parentNode.removeChild(img);
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395
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img.id = null;
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396
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}
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397
|
// only use image from cache if it is not on a layer already
|
|
398
|
if (!img.parentNode) {
|
|
399
|
img.style.visibility = 'hidden';
|
|
400
|
img.style.opacity = 0;
|
|
401
|
tile.setImage(img);
|
|
402
|
// LRU - move tile to the end of the array to mark it as the most
|
|
403
|
// recently used
|
|
404
|
OpenLayers.Util.removeItem(this.tileCacheIndex, tile.url);
|
|
405
|
this.tileCacheIndex.push(tile.url);
|
|
406
|
}
|
|
407
|
}
|
|
408
|
},
|
|
409
|
|
|
410
|
/**
|
|
411
|
* Method: addToCache
|
|
412
|
*
|
|
413
|
* Parameters:
|
|
414
|
* evt - {Object} Listener argument for the tile's loadend event
|
|
415
|
*/
|
|
416
|
addToCache: function(evt) {
|
|
417
|
var tile = evt.object;
|
|
418
|
if (!this.tileCache[tile.url]) {
|
|
419
|
if (!OpenLayers.Element.hasClass(tile.imgDiv, 'olImageLoadError')) {
|
|
420
|
if (this.tileCacheIndex.length >= this.cacheSize) {
|
|
421
|
delete this.tileCache[this.tileCacheIndex[0]];
|
|
422
|
this.tileCacheIndex.shift();
|
|
423
|
}
|
|
424
|
this.tileCache[tile.url] = tile.imgDiv;
|
|
425
|
this.tileCacheIndex.push(tile.url);
|
|
426
|
}
|
|
427
|
}
|
|
428
|
},
|
|
429
|
|
|
430
|
/**
|
|
431
|
* Method: clearTileQueue
|
|
432
|
* Clears the tile queue from tiles of a specific layer
|
|
433
|
*
|
|
434
|
* Parameters:
|
|
435
|
* evt - {Object} Listener argument of the layer's retile event
|
|
436
|
*/
|
|
437
|
clearTileQueue: function(evt) {
|
|
438
|
var layer = evt.object;
|
|
439
|
var tileQueue = this.tileQueue[layer.map.id];
|
|
440
|
for (var i=tileQueue.length-1; i>=0; --i) {
|
|
441
|
if (tileQueue[i].layer === layer) {
|
|
442
|
tileQueue.splice(i, 1);
|
|
443
|
}
|
|
444
|
}
|
|
445
|
},
|
|
446
|
|
|
447
|
/**
|
|
448
|
* Method: destroy
|
|
449
|
*/
|
|
450
|
destroy: function() {
|
|
451
|
for (var i=this.maps.length-1; i>=0; --i) {
|
|
452
|
this.removeMap(this.maps[i]);
|
|
453
|
}
|
|
454
|
this.maps = null;
|
|
455
|
this.tileQueue = null;
|
|
456
|
this.tileQueueId = null;
|
|
457
|
this.tileCache = null;
|
|
458
|
this.tileCacheIndex = null;
|
|
459
|
this._destroyed = true;
|
|
460
|
}
|
|
461
|
|
|
462
|
});
|