source: Dev/trunk/src/client/dojox/geo/openlayers/JsonImport.js

define([
        "dojo/_base/declare",
        "dojo/_base/xhr",
        "dojo/_base/lang",
        "dojo/_base/array",
        "./LineString",
        "./Collection",
        "./GeometryFeature"
], function(declare, xhr, lang, array, LineString, Collection, GeometryFeature){

        /*=====
        dojox.geo.openlayers.__JsonImportArgs = {
                // summary:
                //              The keyword arguments that can be passed in a JsonImport constructor.
                // url: String
                //              The url pointing to the JSON file to load.
                // nextFeature: function
                //              The function called each time a feature is read. The function is called with a GeometryFeature as argument.
                // error: function
                //              Error callback called if something fails.
        };
        =====*/

        return declare("dojox.geo.openlayers.JsonImport", null, {
                // summary:
                //              Class to load JSON formated ShapeFile as output of the JSon Custom Map Converter.
                // description:
                //              This class loads JSON formated ShapeFile produced by the JSon Custom Map Converter.
                //              When loading the JSON file, it calls a iterator function each time a feature is read.
                //              This iterator function is provided as parameter to the constructor.
                //
                constructor : function(params){
                        // summary:
                        //              Construct a new JSON importer.
                        // params: dojox.geo.openlayers.__JsonImportArgs
                        //              The parameters to initialize this JsonImport instance.
                        this._params = params;
                },

                loadData: function(){
                        // summary:
                        //              Triggers the loading.
                        var p = this._params;
                        xhr.get({
                                url: p.url,
                                handleAs: "json",
                                sync: true,
                                load: lang.hitch(this, this._gotData),
                                error: lang.hitch(this, this._loadError)
                        });
                },

                _gotData: function(/* Object */items){
                        // summary:
                        //              Called when loading is complete.
                        // tags:
                        //              private
                        var nf = this._params.nextFeature;
                        if(!lang.isFunction(nf)){
                                return;
                        }

                        var extent = items.layerExtent;
                        var ulx = extent[0];
                        var uly = extent[1];
                        var lrx = ulx + extent[2];
                        var lry = uly + extent[3];

                        var extentLL = items.layerExtentLL;
                        var x1 = extentLL[0];
                        var y1 = extentLL[1];
                        var x2 = x1 + extentLL[2];
                        var y2 = y1 + extentLL[3];

                        var ulxLL = x1;
                        var ulyLL = y2;
                        var lrxLL = x2;
                        var lryLL = y1;

                        var features = items.features;

                        for( var f in features){
                                var o = features[f];
                                var s = o["shape"];
                                var gf = null;
                                if(lang.isArray(s[0])){

                                        var a = new Array();
                                        array.forEach(s, function(item){
                                                var ls = this._makeGeometry(item, ulx, uly, lrx, lry, ulxLL, ulyLL, lrxLL, lryLL);
                                                a.push(ls);
                                        }, this);
                                        var g = new Collection(a);
                                        gf = new GeometryFeature(g);
                                        nf.call(this, gf);

                                }else{
                                        gf = this._makeFeature(s, ulx, uly, lrx, lry, ulxLL, ulyLL, lrxLL, lryLL);
                                        nf.call(this, gf);
                                }
                        }
                        var complete = this._params.complete;
                        if(lang.isFunction(complete)){
                                complete.call(this, complete);
                        }
                },

                _makeGeometry: function(/* Array */s, /* Float */ulx, /* Float */uly, /* Float */lrx, /* Float */
                lry, /* Float */ulxLL, /* Float */ulyLL, /* Float */lrxLL, /* Float */lryLL){
                        // summary:
                        //              Make a geometry with the specified points.
                        // tags:
                        //              private
                        var a = [];
                        var k = 0.0;
                        for( var i = 0; i < s.length - 1; i += 2){
                                var x = s[i];
                                var y = s[i + 1];

                                k = (x - ulx) / (lrx - ulx);
                                var px = k * (lrxLL - ulxLL) + ulxLL;

                                k = (y - uly) / (lry - uly);
                                var py = k * (lryLL - ulyLL) + ulyLL;

                                a.push({
                                        x: px,
                                        y: py
                                });

                        }
                        var ls = new LineString(a);
                        return ls; // LineString
                },

                _makeFeature: function(/* Array */s, /* Float */ulx, /* Float */uly, /* Float */lrx, /* Float */
                lry, /* Float */ulxLL, /* Float */ulyLL, /* Float */lrxLL, /* Float */lryLL){
                        // summary:
                        //              Make a GeometryFeature with the specified points.
                        // tags:
                        //              private
                        var ls = this._makeGeometry(s, ulx, uly, lrx, lry, ulxLL, ulyLL, lrxLL, lryLL);
                        var gf = new GeometryFeature(ls);
                        return gf;
                },

                _loadError: function(){
                        // summary:
                        //              Called when an error occurs. Calls the error function is provided in the parameters.
                        // tags:
                        //              private
                        var f = this._params.error;
                        if(lang.isFunction(f)){
                                f.apply(this, parameters);
                        }
                }
        });
});