gml.js

用来在地图上做操作GIS,在地图上做标记

/* Copyright (c) 2006-2007 MetaCarta, Inc., published under the BSD license.
 * See http://svn.openlayers.org/trunk/openlayers/release-license.txt 
 * for the full text of the license. */

/**
 * @requires OpenLayers/Format/XML.js
 * @requires OpenLayers/Feature/Vector.js
 * @requires OpenLayers/Geometry/Point.js
 * @requires OpenLayers/Geometry/MultiPoint.js
 * @requires OpenLayers/Geometry/LineString.js
 * @requires OpenLayers/Geometry/MultiLineString.js
 * @requires OpenLayers/Geometry/Polygon.js
 * @requires OpenLayers/Geometry/MultiPolygon.js
 *
 * Class: OpenLayers.Format.GML
 * Read/Wite GML. Create a new instance with the <OpenLayers.Format.GML>
 *     constructor.  Supports the GML simple features profile.
 * 
 * Inherits from:
 *  - <OpenLayers.Format>
 */
OpenLayers.Format.GML = OpenLayers.Class(OpenLayers.Format.XML, {
    
    /*
     * APIProperty: featureNS
     * {String} Namespace used for feature attributes.  Default is
     *     "http://mapserver.gis.umn.edu/mapserver".
     */
    featureNS: "http://mapserver.gis.umn.edu/mapserver",
    
    /**
     * APIProperty: featurePrefix
     * {String} Namespace alias (or prefix) for feature nodes.  Default is
     *     "feature".
     */
    featurePrefix: "feature",
    
    /*
     * APIProperty: featureName
     * {String} Element name for features. Default is "featureMember".
     */
    featureName: "featureMember", 
    
    /*
     * APIProperty: layerName
     * {String} Name of data layer. Default is "features".
     */
    layerName: "features",
    
    /**
     * APIProperty: geometry
     * {String} Name of geometry element.  Defaults to "geometry".
     */
    geometryName: "geometry",
    
    /** 
     * APIProperty: collectionName
     * {String} Name of featureCollection element.
     */
    collectionName: "FeatureCollection",
    
    /**
     * APIProperty: gmlns
     * {String} GML Namespace.
     */
    gmlns: "http://www.opengis.net/gml",

    /**
     * APIProperty: extractAttributes
     * {Boolean} Extract attributes from GML.
     */
    extractAttributes: true,
    
    /**
     * Constructor: OpenLayers.Format.GML
     * Create a new parser for GML.
     *
     * Parameters:
     * options - {Object} An optional object whose properties will be set on
     *     this instance.
     */
    initialize: function(options) {
        // compile regular expressions once instead of every time they are used
        this.regExes = {
            trimSpace: (/^\s*|\s*$/g),
            removeSpace: (/\s*/g),
            splitSpace: (/\s+/),
            trimComma: (/\s*,\s*/g)
        };
        OpenLayers.Format.XML.prototype.initialize.apply(this, [options]);
    },

    /**
     * APIMethod: read
     * Read data from a string, and return a list of features. 
     * 
     * Parameters:
     * data - {String} or {DOMElement} data to read/parse.
     *
     * Returns:
     * {Array(<OpenLayers.Feature.Vector>)} An array of features.
     */
    read: function(data) {
        if(typeof data == "string") { 
            data = OpenLayers.Format.XML.prototype.read.apply(this, [data]);
        }
        var featureNodes = this.getElementsByTagNameNS(data.documentElement,
                                                       this.gmlns,
                                                       this.featureName);
        var features = [];
        for(var i=0; i<featureNodes.length; i++) {
            var feature = this.parseFeature(featureNodes[i]);
            if(feature) {
                features.push(feature);
            }
        }
        return features;
    },
    
    /**
     * Method: parseFeature
     * This function is the core of the GML parsing code in OpenLayers.
     *    It creates the geometries that are then attached to the returned
     *    feature, and calls parseAttributes() to get attribute data out.
     *    
     * Parameters:
     * node - {DOMElement} A GML feature node. 
     */
    parseFeature: function(node) {
        // only accept on geometry per feature - look for highest "order"
        var order = ["MultiPolygon", "Polygon",
                     "MultiLineString", "LineString",
                     "MultiPoint", "Point"];
        var type, nodeList, geometry, parser;
        for(var i=0; i<order.length; ++i) {
            type = order[i];
            nodeList = this.getElementsByTagNameNS(node, this.gmlns, type);
            if(nodeList.length > 0) {
                // only deal with first geometry of this type
                var parser = this.parseGeometry[type.toLowerCase()];
                if(parser) {
                    geometry = parser.apply(this, [nodeList[0]]);
                } else {
                    OpenLayers.Console.error("Unsupported geometry type: " +
                                             type);
                }
                // stop looking for different geometry types
                break;
            }
        }
        
        // construct feature (optionally with attributes)
        var attributes;
        if(this.extractAttributes) {
            attributes = this.parseAttributes(node);
        }
        var feature = new OpenLayers.Feature.Vector(geometry, attributes);
        // assign fid - this can come from a "fid" or "id" attribute
        var childNode = node.firstChild;
        var fid;
        while(childNode) {
            if(childNode.nodeType == 1) {
                fid = childNode.getAttribute("fid") ||
                      childNode.getAttribute("id");
                if(fid) {
                    break;
                }
            }
            childNode = childNode.nextSibling;
        }
        feature.fid = fid;
        return feature;
    },
    
    /**
     * Property: parseGeometry
     * Properties of this object are the functions that parse geometries based
     *     on their type.
     */
    parseGeometry: {
        
        /**
         * Method: parseGeometry.point
         * Given a GML node representing a point geometry, create an OpenLayers
         *     point geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.Point>} A point geometry.
         */
        point: function(node) {
            /**
             * Three coordinate variations to consider:
             * 1) <gml:pos>x y z</gml:pos>
             * 2) <gml:coordinates>x, y, z</gml:coordinates>
             * 3) <gml:coord><gml:X>x</gml:X><gml:Y>y</gml:Y></gml:coord>
             */
            var nodeList;
            var coords = [];

            // look for <gml:pos>
            var nodeList = this.getElementsByTagNameNS(node, this.gmlns, "pos");
            if(nodeList.length > 0) {
                coordString = nodeList[0].firstChild.nodeValue;
                coordString = coordString.replace(this.regExes.trimSpace, "");
                coords = coordString.split(this.regExes.splitSpace);
            }

            // look for <gml:coordinates>
            if(coords.length == 0) {
                nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "coordinates");
                if(nodeList.length > 0) {
                    coordString = nodeList[0].firstChild.nodeValue;
                    coordString = coordString.replace(this.regExes.removeSpace,
                                                      "");
                    coords = coordString.split(",");
                }
            }

            // look for <gml:coord>
            if(coords.length == 0) {
                nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "coord");
                if(nodeList.length > 0) {
                    var xList = this.getElementsByTagNameNS(nodeList[0],
                                                            this.gmlns, "X");
                    var yList = this.getElementsByTagNameNS(nodeList[0],
                                                            this.gmlns, "Y");
                    if(xList.length > 0 && yList.length > 0) {
                        coords = [xList[0].firstChild.nodeValue,
                                  yList[0].firstChild.nodeValue];
                    }
                }
            }
                
            // preserve third dimension
            if(coords.length == 2) {
                coords[2] = null;
            }
            return new OpenLayers.Geometry.Point(coords[0], coords[1],
                                                 coords[2]);
        },
        
        /**
         * Method: parseGeometry.multipoint
         * Given a GML node representing a multipoint geometry, create an
         *     OpenLayers multipoint geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.MultiPoint>} A multipoint geometry.
         */
        multipoint: function(node) {
            var nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "Point");
            var components = [];
            if(nodeList.length > 0) {
                var point;
                for(var i=0; i<nodeList.length; ++i) {
                    point = this.parseGeometry.point.apply(this, [nodeList[i]]);
                    if(point) {
                        components.push(point);
                    }
                }
            }
            return new OpenLayers.Geometry.MultiPoint(components);
        },
        
        /**
         * Method: parseGeometry.linestring
         * Given a GML node representing a linestring geometry, create an
         *     OpenLayers linestring geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.LineString>} A linestring geometry.
         */
        linestring: function(node, ring) {
            /**
             * Two coordinate variations to consider:
             * 1) <gml:posList dimension="d">x0 y0 z0 x1 y1 z1</gml:posList>
             * 2) <gml:coordinates>x0, y0, z0 x1, y1, z1</gml:coordinates>
             */
            var nodeList, coordString;
            var coords = [];
            var points = [];

            // look for <gml:posList>
            nodeList = this.getElementsByTagNameNS(node, this.gmlns, "posList");
            if(nodeList.length > 0) {
                coordString = this.concatChildValues(nodeList[0]);
                coordString = coordString.replace(this.regExes.trimSpace, "");
                coords = coordString.split(this.regExes.splitSpace);
                var dim = parseInt(nodeList[0].getAttribute("dimension"));
                var j, x, y, z;
                for(var i=0; i<coords.length/dim; ++i) {
                    j = i * dim;
                    x = coords[j];
                    y = coords[j+1];
                    z = (dim == 2) ? null : coords[j+2];
                    points.push(new OpenLayers.Geometry.Point(x, y, z));
                }
            }

            // look for <gml:coordinates>
            if(coords.length == 0) {
                nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "coordinates");
                if(nodeList.length > 0) {
                    coordString = this.concatChildValues(nodeList[0]);
                    coordString = coordString.replace(this.regExes.trimSpace,
                                                      "");
                    coordString = coordString.replace(this.regExes.trimComma,
                                                      ",");
                    var pointList = coordString.split(this.regExes.splitSpace);
                    for(var i=0; i<pointList.length; ++i) {
                        coords = pointList[i].split(",");
                        if(coords.length == 2) {
                            coords[2] = null;
                        }
                        points.push(new OpenLayers.Geometry.Point(coords[0],
                                                                  coords[1],
                                                                  coords[2]));
                    }
                }
            }

            var line = null;
            if(points.length != 0) {
                if(ring) {
                    line = new OpenLayers.Geometry.LinearRing(points);
                } else {
                    line = new OpenLayers.Geometry.LineString(points);
                }
            }
            return line;
        },
        
        /**
         * Method: parseGeometry.multilinestring
         * Given a GML node representing a multilinestring geometry, create an
         *     OpenLayers multilinestring geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.MultiLineString>} A multilinestring geometry.
         */
        multilinestring: function(node) {
            var nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "LineString");
            var components = [];
            if(nodeList.length > 0) {
                var line;
                for(var i=0; i<nodeList.length; ++i) {
                    line = this.parseGeometry.linestring.apply(this,
                                                               [nodeList[i]]);
                    if(line) {
                        components.push(line);
                    }
                }
            }
            return new OpenLayers.Geometry.MultiLineString(components);