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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for

 * full list of contributors). Published under the 2-clause BSD license.

 * See license.txt in the OpenLayers distribution or repository for the

 * full text of the license. */

/**

 * @requires OpenLayers/Layer/Grid.js

 */

/**

 * Class: OpenLayers.Layer.WMS

 * Instances of OpenLayers.Layer.WMS are used to display data from OGC Web

 *     Mapping Services. Create a new WMS layer with the <OpenLayers.Layer.WMS>

 *     constructor.

 * 

 * Inherits from:

 *  - <OpenLayers.Layer.Grid>

 */

OpenLayers.Layer.WMS = OpenLayers.Class(OpenLayers.Layer.Grid, {

    /**

     * Constant: DEFAULT_PARAMS

     * {Object} Hashtable of default parameter key/value pairs 

     */

    DEFAULT_PARAMS: { service: "WMS",

                      version: "1.1.1",

                      request: "GetMap",

                      styles: "",

                      format: "image/jpeg"

                     },

    /**

     * APIProperty: isBaseLayer

     * {Boolean} Default is true for WMS layer

     */

    isBaseLayer: true,

    /**

     * APIProperty: encodeBBOX

     * {Boolean} Should the BBOX commas be encoded? The WMS spec says 'no', 

     * but some services want it that way. Default false.

     */

    encodeBBOX: false,

    /** 

     * APIProperty: noMagic 

     * {Boolean} If true, the image format will not be automagicaly switched 

     *     from image/jpeg to image/png or image/gif when using 

     *     TRANSPARENT=TRUE. Also isBaseLayer will not changed by the  

     *     constructor. Default false. 

     */ 

    noMagic: false,

    /**

     * Property: yx

     * {Object} Keys in this object are EPSG codes for which the axis order

     *     is to be reversed (yx instead of xy, LatLon instead of LonLat), with

     *     true as value. This is only relevant for WMS versions >= 1.3.0, and

     *     only if yx is not set in <OpenLayers.Projection.defaults> for the

     *     used projection.

     */

    yx: {},

    /**

     * Constructor: OpenLayers.Layer.WMS

     * Create a new WMS layer object

     *

     * Examples:

     *

     * The code below creates a simple WMS layer using the image/jpeg format.

     * (code)

     * var wms = new OpenLayers.Layer.WMS("NASA Global Mosaic",

     *                                    "http://wms.jpl.nasa.gov/wms.cgi", 

     *                                    {layers: "modis,global_mosaic"});

     * (end)

     * Note the 3rd argument (params). Properties added to this object will be

     * added to the WMS GetMap requests used for this layer's tiles. The only

     * mandatory parameter is "layers". Other common WMS params include

     * "transparent", "styles" and "format". Note that the "srs" param will

     * always be ignored. Instead, it will be derived from the baseLayer's or

     * map's projection.

     *

     * The code below creates a transparent WMS layer with additional options.

     * (code)

     * var wms = new OpenLayers.Layer.WMS("NASA Global Mosaic",

     *                                    "http://wms.jpl.nasa.gov/wms.cgi", 

     *                                    {

     *                                        layers: "modis,global_mosaic",

     *                                        transparent: true

     *                                    }, {

     *                                        opacity: 0.5,

     *                                        singleTile: true

     *                                    });

     * (end)

     * Note that by default, a WMS layer is configured as baseLayer. Setting

     * the "transparent" param to true will apply some magic (see <noMagic>).

     * The default image format changes from image/jpeg to image/png, and the

     * layer is not configured as baseLayer.

     *

     * Parameters:

     * name - {String} A name for the layer

     * url - {String} Base url for the WMS

     *                (e.g. http://wms.jpl.nasa.gov/wms.cgi)

     * params - {Object} An object with key/value pairs representing the

     *                   GetMap query string parameters and parameter values.

     * options - {Object} Hashtable of extra options to tag onto the layer.

     *     These options include all properties listed above, plus the ones

     *     inherited from superclasses.

     */

    initialize: function(name, url, params, options) {

        var newArguments = [];

        //uppercase params

        params = OpenLayers.Util.upperCaseObject(params);

        if (parseFloat(params.VERSION) >= 1.3 && !params.EXCEPTIONS) {

            params.EXCEPTIONS = "INIMAGE";

        } 

        newArguments.push(name, url, params, options);

        OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);

        OpenLayers.Util.applyDefaults(

                       this.params, 

                       OpenLayers.Util.upperCaseObject(this.DEFAULT_PARAMS)

                       );

        //layer is transparent        

        if (!this.noMagic && this.params.TRANSPARENT && 

            this.params.TRANSPARENT.toString().toLowerCase() == "true") {

            // unless explicitly set in options, make layer an overlay

            if ( (options == null) || (!options.isBaseLayer) ) {

                this.isBaseLayer = false;

            } 

            // jpegs can never be transparent, so intelligently switch the 

            //  format, depending on the browser's capabilities

            if (this.params.FORMAT == "image/jpeg") {

                this.params.FORMAT = OpenLayers.Util.alphaHack() ? "image/gif"

                                                                 : "image/png";

            }

        }

    },    

    /**

     * Method: clone

     * Create a clone of this layer

     *

     * Returns:

     * {<OpenLayers.Layer.WMS>} An exact clone of this layer

     */

    clone: function (obj) {

        if (obj == null) {

            obj = new OpenLayers.Layer.WMS(this.name,

                                           this.url,

                                           this.params,

                                           this.getOptions());

        }

        //get all additions from superclasses

        obj = OpenLayers.Layer.Grid.prototype.clone.apply(this, [obj]);

        // copy/set any non-init, non-simple values here

        return obj;

    },    

    /**

     * APIMethod: reverseAxisOrder

     * Returns true if the axis order is reversed for the WMS version and

     * projection of the layer.

     * 

     * Returns:

     * {Boolean} true if the axis order is reversed, false otherwise.

     */

    reverseAxisOrder: function() {

        var projCode = this.projection.getCode();

        return parseFloat(this.params.VERSION) >= 1.3 && 

            !!(this.yx[projCode] || (OpenLayers.Projection.defaults[projCode] && 

            OpenLayers.Projection.defaults[projCode].yx));

    },

    /**

     * Method: getURL

     * Return a GetMap query string for this layer

     *

     * Parameters:

     * bounds - {<OpenLayers.Bounds>} A bounds representing the bbox for the

     *                                request.

     *

     * 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 imageSize = this.getImageSize();

        var newParams = {};

        // WMS 1.3 introduced axis order

        var reverseAxisOrder = this.reverseAxisOrder();

        newParams.BBOX = this.encodeBBOX ?

            bounds.toBBOX(null, reverseAxisOrder) :

            bounds.toArray(reverseAxisOrder);

        newParams.WIDTH = imageSize.w;

        newParams.HEIGHT = imageSize.h;

        var requestString = this.getFullRequestString(newParams);

        return requestString;

    },

    /**

     * APIMethod: mergeNewParams

     * Catch changeParams and uppercase the new params to be merged in

     *     before calling changeParams on the super class.

     * 

     *     Once params have been changed, the tiles will be reloaded with

     *     the new parameters.

     * 

     * Parameters:

     * newParams - {Object} Hashtable of new params to use

     */

    mergeNewParams:function(newParams) {

        var upperParams = OpenLayers.Util.upperCaseObject(newParams);

        var newArguments = [upperParams];

        return OpenLayers.Layer.Grid.prototype.mergeNewParams.apply(this, 

                                                             newArguments);

    },

    /** 

     * APIMethod: getFullRequestString

     * Combine the layer's url with its params and these newParams. 

     *   

     *     Add the SRS parameter from projection -- this is probably

     *     more eloquently done via a setProjection() method, but this 

     *     works for now and always.

     *

     * Parameters:

     * newParams - {Object}

     * altUrl - {String} Use this as the url instead of the layer's url

     * 

     * Returns:

     * {String} 

     */

    getFullRequestString:function(newParams, altUrl) {

        var mapProjection = this.map.getProjectionObject();

        var projectionCode = this.projection && this.projection.equals(mapProjection) ?

            this.projection.getCode() :

            mapProjection.getCode();

        var value = (projectionCode == "none") ? null : projectionCode;

        if (parseFloat(this.params.VERSION) >= 1.3) {

            this.params.CRS = value;

        } else {

            this.params.SRS = value;

        }

        if (typeof this.params.TRANSPARENT == "boolean") {

            newParams.TRANSPARENT = this.params.TRANSPARENT ? "TRUE" : "FALSE";

        }

        return OpenLayers.Layer.Grid.prototype.getFullRequestString.apply(

                                                    this, arguments);

    },

    CLASS_NAME: "OpenLayers.Layer.WMS"

});