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
78 lines
2.3 KiB
JavaScript
78 lines
2.3 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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// @require: OpenLayers/Layer/Grid.js
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/**
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* @class
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*/
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OpenLayers.Layer.WorldWind = Class.create();
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OpenLayers.Layer.WorldWind.prototype =
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Object.extend( new OpenLayers.Layer.Grid(), {
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DEFAULT_PARAMS: {
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},
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/** WorldWind layer is always a base layer
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*
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* @type Boolean
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*/
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isBaseLayer: true,
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// LevelZeroTileSizeDegrees
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lzd: null,
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zoomLevels: null,
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initialize: function(name, url, lzd, zoomLevels, params) {
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this.lzd = lzd;
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this.zoomLevels = zoomLevels;
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var newArguments = new Array();
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newArguments.push(name, url, params);
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OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
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this.params = (params ? params : {});
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if (arguments.length > 0 && params) {
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OpenLayers.Util.applyDefaults(
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this.params,
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this.DEFAULT_PARAMS
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);
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}
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},
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addTile:function(bounds,position) {
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if (this.map.getResolution() <= (this.lzd/512)
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&& this.getZoom() <= this.zoomLevels) {
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return new OpenLayers.Tile.Image(this, position, bounds,
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url, this.tileSize);
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} else {
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var tile = new Object();
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tile.draw = function() {};
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tile.destroy = function() {};
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tile.bounds = bounds;
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tile.bounds = position;
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return tile;
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}
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},
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getZoom: function () {
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var zoom = this.map.getZoom();
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var extent = this.map.getMaxExtent();
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zoom = zoom - Math.log(this.map.maxResolution / (this.lzd/512))/Math.log(2);
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return zoom;
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},
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getURL: function (bounds) {
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var deg = this.lzd/Math.pow(2,this.getZoom());
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var x = Math.floor((bounds.left - extent.left)/deg);
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var y = Math.floor((bounds.bottom - extent.bottom)/deg);
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return this.getFullRequestString(
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{ L: zoom,
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X: x,
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Y: y
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});
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},
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/** @final @type String */
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CLASS_NAME: "OpenLayers.Layer.WorldWind"
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});
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