gml.js

用来在地图上做操作GIS,在地图上做标记

        },
        
        /**
         * Method: parseGeometry.polygon
         * Given a GML node representing a polygon geometry, create an
         *     OpenLayers polygon geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.Polygon>} A polygon geometry.
         */
        polygon: function(node) {
            var nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "LinearRing");
            var components = [];
            if(nodeList.length > 0) {
                // this assumes exterior ring first, inner rings after
                var ring;
                for(var i=0; i<nodeList.length; ++i) {
                    ring = this.parseGeometry.linestring.apply(this,
                                                        [nodeList[i], true]);
                    if(ring) {
                        components.push(ring);
                    }
                }
            }
            return new OpenLayers.Geometry.Polygon(components);
        },
        
        /**
         * Method: parseGeometry.multipolygon
         * Given a GML node representing a multipolygon geometry, create an
         *     OpenLayers multipolygon geometry.
         *
         * Parameters:
         * node - {DOMElement} A GML node.
         *
         * Returns:
         * {<OpenLayers.Geometry.MultiPolygon>} A multipolygon geometry.
         */
        multipolygon: function(node) {
            var nodeList = this.getElementsByTagNameNS(node, this.gmlns,
                                                       "Polygon");
            var components = [];
            if(nodeList.length > 0) {
                var polygon;
                for(var i=0; i<nodeList.length; ++i) {
                    polygon = this.parseGeometry.polygon.apply(this,
                                                               [nodeList[i]]);
                    if(polygon) {
                        components.push(polygon);
                    }
                }
            }
            return new OpenLayers.Geometry.MultiPolygon(components);
        }
    },
    
    /**
     * Method: parseAttributes
     *
     * Parameters:
     * node - {<DOMElement>}
     *
     * Returns:
     * {Object} An attributes object.
     */
    parseAttributes: function(node) {
        var attributes = {};
        // assume attributes are children of the first type 1 child
        var childNode = node.firstChild;
        var children, i, child, grandchildren, grandchild, name, value;
        while(childNode) {
            if(childNode.nodeType == 1) {
                // attributes are type 1 children with one type 3 child
                children = childNode.childNodes;
                for(i=0; i<children.length; ++i) {
                    child = children[i];
                    if(child.nodeType == 1) {
                        grandchildren = child.childNodes;
                        if(grandchildren.length == 1) {
                            grandchild = grandchildren[0];
                            if(grandchild.nodeType == 3 ||
                               grandchild.nodeType == 4) {
                                name = (child.prefix) ?
                                        child.nodeName.split(":")[1] :
                                        child.nodeName;
                                value = grandchild.nodeValue.replace(
                                                this.regExes.trimSpace, "");
                                attributes[name] = value;
                            }
                        }
                    }
                }
                break;
            }
            childNode = childNode.nextSibling;
        }
        return attributes;
    },
    
    /**
     * APIMethod: write
     * Generate a GML document string given a list of features. 
     * 
     * Parameters:
     * features - {Array(<OpenLayers.Feature.Vector>)} List of features to
     *     serialize into a string.
     *
     * Returns:
     * {String} A string representing the GML document.
     */
    write: function(features) {
        if(!(features instanceof Array)) {
            features = [features];
        }
        var gml = this.createElementNS("http://www.opengis.net/wfs",
                                       "wfs:" + this.collectionName);
        for(var i=0; i<features.length; i++) {
            gml.appendChild(this.createFeatureXML(features[i]));
        }
        return OpenLayers.Format.XML.prototype.write.apply(this, [gml]);
    },

    /** 
     * Method: createFeatureXML
     * Accept an OpenLayers.Feature.Vector, and build a GML node for it.
     *
     * Parameters:
     * feature - {<OpenLayers.Feature.Vector>} The feature to be built as GML.
     *
     * Returns:
     * {DOMElement} A node reprensting the feature in GML.
     */
    createFeatureXML: function(feature) {
        var geometry = feature.geometry;
        var geometryNode = this.buildGeometryNode(geometry);
        var geomContainer = this.createElementNS(this.featureNS,
                                                 this.featurePrefix + ":" +
                                                 this.geometryName);
        geomContainer.appendChild(geometryNode);
        var featureNode = this.createElementNS(this.gmlns,
                                               "gml:" + this.featureName);
        var featureContainer = this.createElementNS(this.featureNS,
                                                    this.featurePrefix + ":" +
                                                    this.layerName);
        var fid = feature.fid || feature.id;
        featureContainer.setAttribute("fid", fid);
        featureContainer.appendChild(geomContainer);
        for(var attr in feature.attributes) {
            var attrText = this.createTextNode(feature.attributes[attr]); 
            var nodename = attr.substring(attr.lastIndexOf(":") + 1);
            var attrContainer = this.createElementNS(this.featureNS,
                                                     this.featurePrefix + ":" +
                                                     nodename);
            attrContainer.appendChild(attrText);
            featureContainer.appendChild(attrContainer);
        }    
        featureNode.appendChild(featureContainer);
        return featureNode;
    },
    
    /**
     * APIMethod: buildGeometryNode
     */
    buildGeometryNode: function(geometry) {
        var className = geometry.CLASS_NAME;
        var type = className.substring(className.lastIndexOf(".") + 1);
        var builder = this.buildGeometry[type.toLowerCase()];
        return builder.apply(this, [geometry]);
    },

    /**
     * Property: buildGeometry
     * Object containing methods to do the actual geometry node building
     *     based on geometry type.
     */
    buildGeometry: {
        // TBD retrieve the srs from layer
        // srsName is non-standard, so not including it until it's right.
        // gml.setAttribute("srsName",
        //                  "http://www.opengis.net/gml/srs/epsg.xml#4326");

        /**
         * Method: buildGeometry.point
         * Given an OpenLayers point geometry, create a GML point.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Point>} A point geometry.
         *
         * Returns:
         * {DOMElement} A GML point node.
         */
        point: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:Point");
            gml.appendChild(this.buildCoordinatesNode(geometry));
            return gml;
        },
        
        /**
         * Method: buildGeometry.multipoint
         * Given an OpenLayers multipoint geometry, create a GML multipoint.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.MultiPoint>} A multipoint geometry.
         *
         * Returns:
         * {DOMElement} A GML multipoint node.
         */
        multipoint: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:MultiPoint");
            var points = geometry.components;
            var pointMember, pointGeom;
            for(var i=0; i<points.length; i++) { 
                pointMember = this.createElementNS(this.gmlns,
                                                   "gml:pointMember");
                pointGeom = this.buildGeometry.point.apply(this,
                                                               [points[i]]);
                pointMember.appendChild(pointGeom);
                gml.appendChild(pointMember);
            }
            return gml;            
        },
        
        /**
         * Method: buildGeometry.linestring
         * Given an OpenLayers linestring geometry, create a GML linestring.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.LineString>} A linestring geometry.
         *
         * Returns:
         * {DOMElement} A GML linestring node.
         */
        linestring: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:LineString");
            gml.appendChild(this.buildCoordinatesNode(geometry));
            return gml;
        },
        
        /**
         * Method: buildGeometry.multilinestring
         * Given an OpenLayers multilinestring geometry, create a GML
         *     multilinestring.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.MultiLineString>} A multilinestring
         *     geometry.
         *
         * Returns:
         * {DOMElement} A GML multilinestring node.
         */
        multilinestring: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:MultiLineString");
            var lines = geometry.components;
            var lineMember, lineGeom;
            for(var i=0; i<lines.length; ++i) {
                lineMember = this.createElementNS(this.gmlns,
                                                  "gml:lineStringMember");
                lineGeom = this.buildGeometry.linestring.apply(this,
                                                                   [lines[i]]);
                lineMember.appendChild(lineGeom);
                gml.appendChild(lineMember);
            }
            return gml;
        },
        
        /**
         * Method: buildGeometry.linearring
         * Given an OpenLayers linearring geometry, create a GML linearring.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.LinearRing>} A linearring geometry.
         *
         * Returns:
         * {DOMElement} A GML linearring node.
         */
        linearring: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:LinearRing");
            gml.appendChild(this.buildCoordinatesNode(geometry));
            return gml;
        },
        
        /**
         * Method: buildGeometry.polygon
         * Given an OpenLayers polygon geometry, create a GML polygon.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Polygon>} A polygon geometry.
         *
         * Returns:
         * {DOMElement} A GML polygon node.
         */
        polygon: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:Polygon");
            var rings = geometry.components;
            var ringMember, ringGeom, type;
            for(var i=0; i<rings.length; ++i) {
                type = (i==0) ? "outerBoundaryIs" : "innerBoundaryIs";
                ringMember = this.createElementNS(this.gmlns,
                                                  "gml:" + type);
                ringGeom = this.buildGeometry.linearring.apply(this,
                                                                   [rings[i]]);
                ringMember.appendChild(ringGeom);
                gml.appendChild(ringMember);
            }
            return gml;
        },
        
        /**
         * Method: buildGeometry.multipolygon
         * Given an OpenLayers multipolygon geometry, create a GML multipolygon.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.MultiPolygon>} A multipolygon
         *     geometry.
         *
         * Returns:
         * {DOMElement} A GML multipolygon node.
         */
        multipolygon: function(geometry) {
            var gml = this.createElementNS(this.gmlns, "gml:MultiPolygon");
            var polys = geometry.components;
            var polyMember, polyGeom;
            for(var i=0; i<polys.length; ++i) {
                polyMember = this.createElementNS(this.gmlns,
                                                  "gml:polygonMember");
                polyGeom = this.buildGeometry.polygon.apply(this,
                                                                [polys[i]]);
                polyMember.appendChild(polyGeom);
                gml.appendChild(polyMember);
            }
            return gml;
        }
    },

    /**
     * Method: buildCoordinates
     * builds the coordinates XmlNode
     * <gml:coordinates decimal="." cs="," ts=" ">...</gml:coordinates>
     *
     * Parameters: 
     * geometry - {<OpenLayers.Geometry>} 
     *
     * Returns:
     * {XmlNode} created xmlNode
     */
    buildCoordinatesNode: function(geometry) {
        var coordinatesNode = this.createElementNS(this.gmlns,
                                                   "gml:coordinates");
        coordinatesNode.setAttribute("decimal", ".");
        coordinatesNode.setAttribute("cs", ",");
        coordinatesNode.setAttribute("ts", " ");
        
        var points = (geometry.components) ? geometry.components : [geometry];
        var parts = [];
        for(var i=0; i<points.length; i++) {
            parts.push(points[i].x + "," + points[i].y);
        }

        var txtNode = this.createTextNode(parts.join(" "));
        coordinatesNode.appendChild(txtNode);
        
        return coordinatesNode;
    },

    CLASS_NAME: "OpenLayers.Format.GML" 
});