kml.js

用来在地图上做操作GIS,在地图上做标记

     */
    parseAttributes: function(node) {
        var attributes = {};
        // assume attribute nodes are type 1 children with a type 3 child
        var child, grandchildren, grandchild;
        var children = node.childNodes;
        for(var 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;
                    }
                }
            }
        }
        return attributes;
    },

    /**
     * APIMethod: write
     * Accept Feature Collection, and return a string. 
     * 
     * Parameters:
     * features - An array of <OpenLayers.Feature.Vector> features.
     *
     * Returns:
     * {String} A KML string.
     */
     write: function(features) {
        if(!(features instanceof Array)) {
            features = [features];
        }
        var kml = this.createElementNS(this.kmlns, "kml");
        var folder = this.createFolderXML();
        for(var i=0; i<features.length; ++i) {
            folder.appendChild(this.createPlacemarkXML(features[i]));
        }
        kml.appendChild(folder);
        return OpenLayers.Format.XML.prototype.write.apply(this, [kml]);
     },

    /**
     * Method: createFolderXML
     * Creates and returns a KML folder node
     * 
     * Returns:
     * {DOMElement}
     */
    createFolderXML: function() {
        // Folder name
        var folderName = this.createElementNS(this.kmlns, "name");
        var folderNameText = this.createTextNode(this.foldersName); 
        folderName.appendChild(folderNameText);

        // Folder description
        var folderDesc = this.createElementNS(this.kmlns, "description");        
        var folderDescText = this.createTextNode(this.foldersDesc); 
        folderDesc.appendChild(folderDescText);

        // Folder
        var folder = this.createElementNS(this.kmlns, "Folder");
        folder.appendChild(folderName);
        folder.appendChild(folderDesc);
        
        return folder;
    },

    /**
     * Method: createPlacemarkXML
     * Creates and returns a KML placemark node representing the given feature. 
     * 
     * Parameters:
     * feature - {<OpenLayers.Feature.Vector>}
     * 
     * Returns:
     * {DOMElement}
     */
    createPlacemarkXML: function(feature) {        
        // Placemark name
        var placemarkName = this.createElementNS(this.kmlns, "name");
        var name = (feature.attributes.name) ?
                    feature.attributes.name : feature.id;
        placemarkName.appendChild(this.createTextNode(name));

        // Placemark description
        var placemarkDesc = this.createElementNS(this.kmlns, "description");
        var desc = (feature.attributes.description) ?
                    feature.attributes.description : this.placemarksDesc;
        placemarkDesc.appendChild(this.createTextNode(desc));
        
        // Placemark
        var placemarkNode = this.createElementNS(this.kmlns, "Placemark");
        if(feature.fid != null) {
            placemarkNode.setAttribute("id", feature.fid);
        }
        placemarkNode.appendChild(placemarkName);
        placemarkNode.appendChild(placemarkDesc);

        // Geometry node (Point, LineString, etc. nodes)
        var geometryNode = this.buildGeometryNode(feature.geometry);
        placemarkNode.appendChild(geometryNode);        
        
        // TBD - deal with remaining (non name/description) attributes.
        return placemarkNode;
    },    

    /**
     * Method: buildGeometryNode
     * Builds and returns a KML geometry node with the given geometry.
     * 
     * Parameters:
     * geometry - {<OpenLayers.Geometry>}
     * 
     * Returns:
     * {DOMElement}
     */
    buildGeometryNode: function(geometry) {
        var className = geometry.CLASS_NAME;
        var type = className.substring(className.lastIndexOf(".") + 1);
        var builder = this.buildGeometry[type.toLowerCase()];
        var node = null;
        if(builder) {
            node = builder.apply(this, [geometry]);
        }
        return node;
    },

    /**
     * Property: buildGeometry
     * Object containing methods to do the actual geometry node building
     *     based on geometry type.
     */
    buildGeometry: {
        // TBD: Anybody care about namespace aliases here (these nodes have
        //    no prefixes)?

        /**
         * Method: buildGeometry.point
         * Given an OpenLayers point geometry, create a KML point.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Point>} A point geometry.
         *
         * Returns:
         * {DOMElement} A KML point node.
         */
        point: function(geometry) {
            var kml = this.createElementNS(this.kmlns, "Point");
            kml.appendChild(this.buildCoordinatesNode(geometry));
            return kml;
        },
        
        /**
         * Method: buildGeometry.multipoint
         * Given an OpenLayers multipoint geometry, create a KML
         *     GeometryCollection.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Point>} A multipoint geometry.
         *
         * Returns:
         * {DOMElement} A KML GeometryCollection node.
         */
        multipoint: function(geometry) {
            return this.buildGeometry.collection(geometry);
        },

        /**
         * Method: buildGeometry.linestring
         * Given an OpenLayers linestring geometry, create a KML linestring.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.LineString>} A linestring geometry.
         *
         * Returns:
         * {DOMElement} A KML linestring node.
         */
        linestring: function(geometry) {
            var kml = this.createElementNS(this.kmlns, "LineString");
            kml.appendChild(this.buildCoordinatesNode(geometry));
            return kml;
        },
        
        /**
         * Method: buildGeometry.multilinestring
         * Given an OpenLayers multilinestring geometry, create a KML
         *     GeometryCollection.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Point>} A multilinestring geometry.
         *
         * Returns:
         * {DOMElement} A KML GeometryCollection node.
         */
        multilinestring: function(geometry) {
            return this.buildGeometry.collection(geometry);
        },

        /**
         * Method: buildGeometry.linearring
         * Given an OpenLayers linearring geometry, create a KML linearring.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.LinearRing>} A linearring geometry.
         *
         * Returns:
         * {DOMElement} A KML linearring node.
         */
        linearring: function(geometry) {
            var kml = this.createElementNS(this.kmlns, "LinearRing");
            kml.appendChild(this.buildCoordinatesNode(geometry));
            return kml;
        },
        
        /**
         * Method: buildGeometry.polygon
         * Given an OpenLayers polygon geometry, create a KML polygon.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Polygon>} A polygon geometry.
         *
         * Returns:
         * {DOMElement} A KML polygon node.
         */
        polygon: function(geometry) {
            var kml = this.createElementNS(this.kmlns, "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.kmlns, type);
                ringGeom = this.buildGeometry.linearring.apply(this,
                                                               [rings[i]]);
                ringMember.appendChild(ringGeom);
                kml.appendChild(ringMember);
            }
            return kml;
        },
        
        /**
         * Method: buildGeometry.multipolygon
         * Given an OpenLayers multipolygon geometry, create a KML
         *     GeometryCollection.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Point>} A multipolygon geometry.
         *
         * Returns:
         * {DOMElement} A KML GeometryCollection node.
         */
        multipolygon: function(geometry) {
            return this.buildGeometry.collection(geometry);
        },

        /**
         * Method: buildGeometry.collection
         * Given an OpenLayers geometry collection, create a KML MultiGeometry.
         *
         * Parameters:
         * geometry - {<OpenLayers.Geometry.Collection>} A geometry collection.
         *
         * Returns:
         * {DOMElement} A KML MultiGeometry node.
         */
        collection: function(geometry) {
            var kml = this.createElementNS(this.kmlns, "MultiGeometry");
            var child;
            for(var i=0; i<geometry.components.length; ++i) {
                child = this.buildGeometryNode.apply(this,
                                                     [geometry.components[i]]);
                if(child) {
                    kml.appendChild(child);
                }
            }
            return kml;
        }
    },

    /**
     * Method: buildCoordinatesNode
     * Builds and returns the KML coordinates node with the given geometry
     * <coordinates>...</coordinates>
     * 
     * Parameters:
     * geometry - {<OpenLayers.Geometry>}
     * 
     * Return:
     * {DOMElement}
     */     
    buildCoordinatesNode: function(geometry) {
        var coordinatesNode = this.createElementNS(this.kmlns, "coordinates");
        
        var path;
        var points = geometry.components;
        if(points) {
            // LineString or LinearRing
            var point;
            var numPoints = points.length;
            var parts = new Array(numPoints);
            for(var i=0; i<numPoints; ++i) {
                point = points[i];
                parts[i] = point.x + "," + point.y;
            }
            path = parts.join(" ");
        } else {
            // Point
            path = geometry.x + "," + geometry.y;
        }
        
        var txtNode = this.createTextNode(path);
        coordinatesNode.appendChild(txtNode);
        
        return coordinatesNode;
    },    

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