WorldWind.js
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/* Copyright (c) 2006-2011 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the Clear BSD license.
* See http://svn.openlayers.org/trunk/openlayers/license.txt for the
* full text of the license. */
/**
* @requires OpenLayers/Layer/Grid.js
*/
/**
* Class: OpenLayers.Layer.WorldWind
*
* Inherits from:
* - <OpenLayers.Layer.Grid>
*/
OpenLayers.Layer.WorldWind = OpenLayers.Class(OpenLayers.Layer.Grid, {
DEFAULT_PARAMS: {
},
/**
* APIProperty: isBaseLayer
* {Boolean} WorldWind layer is a base layer by default.
*/
isBaseLayer: true,
/**
* APIProperty: lzd
* {Float} LevelZeroTileSizeDegrees
*/
lzd: null,
/**
* APIProperty: zoomLevels
* {Integer} Number of zoom levels.
*/
zoomLevels: null,
/**
* Constructor: OpenLayers.Layer.WorldWind
*
* Parameters:
* name - {String} Name of Layer
* url - {String} Base URL
* lzd - {Float} Level zero tile size degrees
* zoomLevels - {Integer} number of zoom levels
* params - {Object} additional parameters
* options - {Object} additional options
*/
initialize: function(name, url, lzd, zoomLevels, params, options) {
this.lzd = lzd;
this.zoomLevels = zoomLevels;
var newArguments = [];
newArguments.push(name, url, params, options);
OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
this.params = OpenLayers.Util.applyDefaults(
this.params, this.DEFAULT_PARAMS
);
},
/**
* Method: getZoom
* Convert map zoom to WW zoom.
*/
getZoom: function () {
var zoom = this.map.getZoom();
var extent = this.map.getMaxExtent();
zoom = zoom - Math.log(this.maxResolution / (this.lzd/512))/Math.log(2);
return zoom;
},
/**
* Method: getURL
*
* Parameters:
* bounds - {<OpenLayers.Bounds>}
*
* Returns:
* {String} A string with the layer's url and parameters and also the
* passed-in bounds and appropriate tile size specified as
* parameters
*/
getURL: function (bounds) {
bounds = this.adjustBounds(bounds);
var zoom = this.getZoom();
var extent = this.map.getMaxExtent();
var deg = this.lzd/Math.pow(2,this.getZoom());
var x = Math.floor((bounds.left - extent.left)/deg);
var y = Math.floor((bounds.bottom - extent.bottom)/deg);
if (this.map.getResolution() <= (this.lzd/512)
&& this.getZoom() <= this.zoomLevels) {
return this.getFullRequestString(
{ L: zoom,
X: x,
Y: y
});
} else {
return OpenLayers.Util.getImagesLocation() + "blank.gif";
}
},
CLASS_NAME: "OpenLayers.Layer.WorldWind"
});