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  • Committer: Deng Dongpo
  • Date: 2010-08-01 09:29:44 UTC
  • Revision ID: dongpo@dhcp-21193.iis.sinica.edu.tw-20100801092944-8t9obt4xtl7otesb
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static/scripts/gis/openlayers/lib/OpenLayers/Layer/WorldWind.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/Layer/Grid.js
 
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 */
 
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/**
 
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 * Class: OpenLayers.Layer.WorldWind
 
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 * 
 
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 * Inherits from:
 
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 *  - <OpenLayers.Layer.Grid>
 
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 */
 
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OpenLayers.Layer.WorldWind = OpenLayers.Class(OpenLayers.Layer.Grid, {
 
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    DEFAULT_PARAMS: {
 
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    },
 
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    /**
 
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     * APIProperty: isBaseLayer
 
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     * WorldWind layer is a base layer by default.
 
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     */
 
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    isBaseLayer: true,    
 
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    /** 
 
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     * APIProperty: lzd
 
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     * LevelZeroTileSizeDegrees
 
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     */
 
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    lzd: null,
 
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    /**
 
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     * APIProperty: zoomLevels
 
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     * Number of zoom levels.
 
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     */
 
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    zoomLevels: null,
 
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    /**
 
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     * Constructor: OpenLayers.Layer.WorldWind
 
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     * 
 
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     * Parameters:
 
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     * name - {String} Name of Layer
 
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     * url - {String} Base URL  
 
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     * lzd - {Float} Level zero tile size degrees 
 
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     * zoomLevels - {Int} number of zoom levels
 
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     * params - {Object} additional parameters
 
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     * options - {Object} additional options
 
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     */
 
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    initialize: function(name, url, lzd, zoomLevels, params, options) {
 
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        this.lzd = lzd;
 
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        this.zoomLevels = zoomLevels;
 
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        var newArguments = [];
 
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        newArguments.push(name, url, params, options);
 
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        OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
 
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        this.params = OpenLayers.Util.applyDefaults(
 
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            this.params, this.DEFAULT_PARAMS
 
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        );
 
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    },
 
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    /**
 
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     * Method: addTile
 
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     * 
 
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     * Parameters:
 
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     * bounds - {<OpenLayers.Bounds>}
 
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     * position - {<OpenLayers.Pixel>}
 
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     * 
 
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     * Returns:
 
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     * {<OpenLayers.Tile.Image>} The added OpenLayers.Tile.Image
 
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     */
 
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    addTile:function(bounds,position) {
 
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        return new OpenLayers.Tile.Image(this, position, bounds, 
 
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                                             null, this.tileSize);
 
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    },
 
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    /**
 
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     * Method: getZoom
 
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     * Convert map zoom to WW zoom.
 
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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.maxResolution / (this.lzd/512))/Math.log(2);
 
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        return zoom;
 
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    },
 
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    /**
 
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     * Method: getURL
 
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     *
 
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     * Parameters:
 
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     * bounds - {<OpenLayers.Bounds>} 
 
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     *
 
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     * Returns:
 
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     * {String} A string with the layer's url and parameters and also the 
 
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     *           passed-in bounds and appropriate tile size specified as 
 
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     *           parameters
 
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     */
 
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    getURL: function (bounds) {
 
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        bounds = this.adjustBounds(bounds);
 
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        var zoom = this.getZoom();
 
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        var extent = this.map.getMaxExtent();
 
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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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        if (this.map.getResolution() <= (this.lzd/512)
 
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            && this.getZoom() <= this.zoomLevels) {
 
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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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        } else {
 
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            return OpenLayers.Util.getImagesLocation() + "blank.gif";
 
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        }
 
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    },
 
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    CLASS_NAME: "OpenLayers.Layer.WorldWind"
 
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});