| /* Copyright (c) 2006-2010 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.js | |
| * @requires OpenLayers/Projection.js | |
| */ | |
| /** | |
| * Class: OpenLayers.Layer.SphericalMercator | |
| * A mixin for layers that wraps up the pieces neccesary to have a coordinate | |
| * conversion for working with commercial APIs which use a spherical | |
| * mercator projection. Using this layer as a base layer, additional | |
| * layers can be used as overlays if they are in the same projection. | |
| * | |
| * A layer is given properties of this object by setting the sphericalMercator | |
| * property to true. | |
| * | |
| * More projection information: | |
| * - http://spatialreference.org/ref/user/google-projection/ | |
| * | |
| * Proj4 Text: | |
| * +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 | |
| * +k=1.0 +units=m +nadgrids=@null +no_defs | |
| * | |
| * WKT: | |
| * 900913=PROJCS["WGS84 / Simple Mercator", GEOGCS["WGS 84", | |
| * DATUM["WGS_1984", SPHEROID["WGS_1984", 6378137.0, 298.257223563]], | |
| * PRIMEM["Greenwich", 0.0], UNIT["degree", 0.017453292519943295], | |
| * AXIS["Longitude", EAST], AXIS["Latitude", NORTH]], | |
| * PROJECTION["Mercator_1SP_Google"], | |
| * PARAMETER["latitude_of_origin", 0.0], PARAMETER["central_meridian", 0.0], | |
| * PARAMETER["scale_factor", 1.0], PARAMETER["false_easting", 0.0], | |
| * PARAMETER["false_northing", 0.0], UNIT["m", 1.0], AXIS["x", EAST], | |
| * AXIS["y", NORTH], AUTHORITY["EPSG","900913"]] | |
| */ | |
| OpenLayers.Layer.SphericalMercator = { | |
| /** | |
| * Method: getExtent | |
| * Get the map's extent. | |
| * | |
| * Returns: | |
| * {<OpenLayers.Bounds>} The map extent. | |
| */ | |
| getExtent: function() { | |
| var extent = null; | |
| if (this.sphericalMercator) { | |
| extent = this.map.calculateBounds(); | |
| } else { | |
| extent = OpenLayers.Layer.FixedZoomLevels.prototype.getExtent.apply(this); | |
| } | |
| return extent; | |
| }, | |
| /** | |
| * Method: getLonLatFromViewPortPx | |
| * Get a map location from a pixel location | |
| * | |
| * Parameters: | |
| * viewPortPx - {<OpenLayers.Pixel>} | |
| * | |
| * Returns: | |
| * {<OpenLayers.LonLat>} An OpenLayers.LonLat which is the passed-in view | |
| * port OpenLayers.Pixel, translated into lon/lat by map lib | |
| * If the map lib is not loaded or not centered, returns null | |
| */ | |
| getLonLatFromViewPortPx: function (viewPortPx) { | |
| return OpenLayers.Layer.prototype.getLonLatFromViewPortPx.apply(this, arguments); | |
| }, | |
| /** | |
| * Method: getViewPortPxFromLonLat | |
| * Get a pixel location from a map location | |
| * | |
| * Parameters: | |
| * lonlat - {<OpenLayers.LonLat>} | |
| * | |
| * Returns: | |
| * {<OpenLayers.Pixel>} An OpenLayers.Pixel which is the passed-in | |
| * OpenLayers.LonLat, translated into view port pixels by map lib | |
| * If map lib is not loaded or not centered, returns null | |
| */ | |
| getViewPortPxFromLonLat: function (lonlat) { | |
| return OpenLayers.Layer.prototype.getViewPortPxFromLonLat.apply(this, arguments); | |
| }, | |
| /** | |
| * Method: initMercatorParameters | |
| * Set up the mercator parameters on the layer: resolutions, | |
| * projection, units. | |
| */ | |
| initMercatorParameters: function() { | |
| // set up properties for Mercator - assume EPSG:900913 | |
| this.RESOLUTIONS = []; | |
| var maxResolution = 156543.0339; | |
| for(var zoom=0; zoom<=this.MAX_ZOOM_LEVEL; ++zoom) { | |
| this.RESOLUTIONS[zoom] = maxResolution / Math.pow(2, zoom); | |
| } | |
| this.units = "m"; | |
| this.projection = this.projection || "EPSG:900913"; | |
| }, | |
| /** | |
| * APIMethod: forwardMercator | |
| * Given a lon,lat in EPSG:4326, return a point in Spherical Mercator. | |
| * | |
| * Parameters: | |
| * lon - {float} | |
| * lat - {float} | |
| * | |
| * Returns: | |
| * {<OpenLayers.LonLat>} The coordinates transformed to Mercator. | |
| */ | |
| forwardMercator: function(lon, lat) { | |
| var x = lon * 20037508.34 / 180; | |
| var y = Math.log(Math.tan((90 + lat) * Math.PI / 360)) / (Math.PI / 180); | |
| y = y * 20037508.34 / 180; | |
| return new OpenLayers.LonLat(x, y); | |
| }, | |
| /** | |
| * APIMethod: inverseMercator | |
| * Given a x,y in Spherical Mercator, return a point in EPSG:4326. | |
| * | |
| * Parameters: | |
| * x - {float} A map x in Spherical Mercator. | |
| * y - {float} A map y in Spherical Mercator. | |
| * | |
| * Returns: | |
| * {<OpenLayers.LonLat>} The coordinates transformed to EPSG:4326. | |
| */ | |
| inverseMercator: function(x, y) { | |
| var lon = (x / 20037508.34) * 180; | |
| var lat = (y / 20037508.34) * 180; | |
| lat = 180/Math.PI * (2 * Math.atan(Math.exp(lat * Math.PI / 180)) - Math.PI / 2); | |
| return new OpenLayers.LonLat(lon, lat); | |
| }, | |
| /** | |
| * Method: projectForward | |
| * Given an object with x and y properties in EPSG:4326, modify the x,y | |
| * properties on the object to be the Spherical Mercator projected | |
| * coordinates. | |
| * | |
| * Parameters: | |
| * point - {Object} An object with x and y properties. | |
| * | |
| * Returns: | |
| * {Object} The point, with the x and y properties transformed to spherical | |
| * mercator. | |
| */ | |
| projectForward: function(point) { | |
| var lonlat = OpenLayers.Layer.SphericalMercator.forwardMercator(point.x, point.y); | |
| point.x = lonlat.lon; | |
| point.y = lonlat.lat; | |
| return point; | |
| }, | |
| /** | |
| * Method: projectInverse | |
| * Given an object with x and y properties in Spherical Mercator, modify | |
| * the x,y properties on the object to be the unprojected coordinates. | |
| * | |
| * Parameters: | |
| * point - {Object} An object with x and y properties. | |
| * | |
| * Returns: | |
| * {Object} The point, with the x and y properties transformed from | |
| * spherical mercator to unprojected coordinates.. | |
| */ | |
| projectInverse: function(point) { | |
| var lonlat = OpenLayers.Layer.SphericalMercator.inverseMercator(point.x, point.y); | |
| point.x = lonlat.lon; | |
| point.y = lonlat.lat; | |
| return point; | |
| } | |
| }; | |
| /** | |
| * Note: Two transforms declared | |
| * Transforms from EPSG:4326 to EPSG:900913 and from EPSG:900913 to EPSG:4326 | |
| * are set by this class. | |
| */ | |
| OpenLayers.Projection.addTransform("EPSG:4326", "EPSG:900913", | |
| OpenLayers.Layer.SphericalMercator.projectForward); | |
| OpenLayers.Projection.addTransform("EPSG:900913", "EPSG:4326", | |
| OpenLayers.Layer.SphericalMercator.projectInverse); | |