wkt.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.js
 * @requires OpenLayers/Feature/Vector.js
 * 
 * Class: OpenLayers.Format.WKT
 * Class for reading and writing Well-Known Text.  Create a new instance
 * with the <OpenLayers.Format.WKT> constructor.
 * 
 * Inherits from:
 *  - <OpenLayers.Format>
 */
OpenLayers.Format.WKT = OpenLayers.Class(OpenLayers.Format, {
    
    /**
     * Constructor: OpenLayers.Format.WKT
     * Create a new parser for WKT
     *
     * Parameters:
     * options - {Object} An optional object whose properties will be set on
     *           this instance
     *
     * Returns:
     * {<OpenLayers.Format.WKT>} A new WKT parser.
     */
    initialize: function(options) {
        this.regExes = {
            'typeStr': /^\s*(\w+)\s*\(\s*(.*)\s*\)\s*$/,
            'spaces': /\s+/,
            'parenComma': /\)\s*,\s*\(/,
            'doubleParenComma': /\)\s*\)\s*,\s*\(\s*\(/,  // can't use {2} here
            'trimParens': /^\s*\(?(.*?)\)?\s*$/
        };
        OpenLayers.Format.prototype.initialize.apply(this, [options]);
    },

    /**
     * Method: read
     * Deserialize a WKT string and return a vector feature or an
     * array of vector features.  Supports WKT for POINT, MULTIPOINT,
     * LINESTRING, MULTILINESTRING, POLYGON, MULTIPOLYGON, and
     * GEOMETRYCOLLECTION.
     *
     * Parameters:
     * wkt - {String} A WKT string
     *
     * Returns:
     * {<OpenLayers.Feature.Vector>|Array} A feature or array of features for
     * GEOMETRYCOLLECTION WKT.
     */
    read: function(wkt) {
        var features, type, str;
        var matches = this.regExes.typeStr.exec(wkt);
        if(matches) {
            type = matches[1].toLowerCase();
            str = matches[2];
            if(this.parse[type]) {
                features = this.parse[type].apply(this, [str]);
            }
        }
        return features;
    },

    /**
     * Method: write
     * Serialize a feature or array of features into a WKT string.
     *
     * Parameters:
     * features - {<OpenLayers.Feature.Vector>|Array} A feature or array of
     *            features
     *
     * Returns:
     * {String} The WKT string representation of the input geometries
     */
    write: function(features) {
        var collection, geometry, type, data, isCollection;
        if(features.constructor == Array) {
            collection = features;
            isCollection = true;
        } else {
            collection = [features];
            isCollection = false;
        }
        var pieces = [];
        if(isCollection) {
            pieces.push('GEOMETRYCOLLECTION(');
        }
        for(var i=0; i<collection.length; ++i) {
            if(isCollection && i>0) {
                pieces.push(',');
            }
            geometry = collection[i].geometry;
            type = geometry.CLASS_NAME.split('.')[2].toLowerCase();
            if(!this.extract[type]) {
                return null;
            }
            data = this.extract[type].apply(this, [geometry]);
            pieces.push(type.toUpperCase() + '(' + data + ')');
        }
        if(isCollection) {
            pieces.push(')');
        }
        return pieces.join('');
    },
    
    /**
     * Object with properties corresponding to the geometry types.
     * Property values are functions that do the actual data extraction.
     */
    extract: {
        /**
         * Return a space delimited string of point coordinates.
         * @param {<OpenLayers.Geometry.Point>} point
         * @returns {String} A string of coordinates representing the point
         */
        'point': function(point) {
            return point.x + ' ' + point.y;
        },

        /**
         * Return a comma delimited string of point coordinates from a multipoint.
         * @param {<OpenLayers.Geometry.MultiPoint>} multipoint
         * @returns {String} A string of point coordinate strings representing
         *                  the multipoint
         */
        'multipoint': function(multipoint) {
            var array = [];
            for(var i=0; i<multipoint.components.length; ++i) {
                array.push(this.extract.point.apply(this, [multipoint.components[i]]));
            }
            return array.join(',');
        },
        
        /**
         * Return a comma delimited string of point coordinates from a line.
         * @param {<OpenLayers.Geometry.LineString>} linestring
         * @returns {String} A string of point coordinate strings representing
         *                  the linestring
         */
        'linestring': function(linestring) {
            var array = [];
            for(var i=0; i<linestring.components.length; ++i) {
                array.push(this.extract.point.apply(this, [linestring.components[i]]));
            }
            return array.join(',');
        },

        /**
         * Return a comma delimited string of linestring strings from a multilinestring.
         * @param {<OpenLayers.Geometry.MultiLineString>} multilinestring
         * @returns {String} A string of of linestring strings representing
         *                  the multilinestring
         */
        'multilinestring': function(multilinestring) {
            var array = [];
            for(var i=0; i<multilinestring.components.length; ++i) {
                array.push('(' +
                           this.extract.linestring.apply(this, [multilinestring.components[i]]) +
                           ')');
            }
            return array.join(',');
        },
        
        /**
         * Return a comma delimited string of linear ring arrays from a polygon.
         * @param {<OpenLayers.Geometry.Polygon>} polygon
         * @returns {String} An array of linear ring arrays representing the polygon
         */
        'polygon': function(polygon) {
            var array = [];
            for(var i=0; i<polygon.components.length; ++i) {
                array.push('(' +
                           this.extract.linestring.apply(this, [polygon.components[i]]) +
                           ')');
            }
            return array.join(',');
        },

        /**
         * Return an array of polygon arrays from a multipolygon.
         * @param {<OpenLayers.Geometry.MultiPolygon>} multipolygon
         * @returns {Array} An array of polygon arrays representing
         *                  the multipolygon
         */
        'multipolygon': function(multipolygon) {
            var array = [];
            for(var i=0; i<multipolygon.components.length; ++i) {
                array.push('(' +
                           this.extract.polygon.apply(this, [multipolygon.components[i]]) +
                           ')');
            }
            return array.join(',');
        }

    },

    /**
     * Object with properties corresponding to the geometry types.
     * Property values are functions that do the actual parsing.
     */
    parse: {
        /**
         * Return point feature given a point WKT fragment.
         * @param {String} str A WKT fragment representing the point
         * @returns {<OpenLayers.Feature.Vector>} A point feature
         * @private
         */
        'point': function(str) {
            var coords = OpenLayers.String.trim(str).split(this.regExes.spaces);
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.Point(coords[0], coords[1])
            );
        },

        /**
         * Return a multipoint feature given a multipoint WKT fragment.
         * @param {String} A WKT fragment representing the multipoint
         * @returns {<OpenLayers.Feature.Vector>} A multipoint feature
         * @private
         */
        'multipoint': function(str) {
            var points = OpenLayers.String.trim(str).split(',');
            var components = [];
            for(var i=0; i<points.length; ++i) {
                components.push(this.parse.point.apply(this, [points[i]]).geometry);
            }
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.MultiPoint(components)
            );
        },
        
        /**
         * Return a linestring feature given a linestring WKT fragment.
         * @param {String} A WKT fragment representing the linestring
         * @returns {<OpenLayers.Feature.Vector>} A linestring feature
         * @private
         */
        'linestring': function(str) {
            var points = OpenLayers.String.trim(str).split(',');
            var components = [];
            for(var i=0; i<points.length; ++i) {
                components.push(this.parse.point.apply(this, [points[i]]).geometry);
            }
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.LineString(components)
            );
        },

        /**
         * Return a multilinestring feature given a multilinestring WKT fragment.
         * @param {String} A WKT fragment representing the multilinestring
         * @returns {<OpenLayers.Feature.Vector>} A multilinestring feature
         * @private
         */
        'multilinestring': function(str) {
            var line;
            var lines = OpenLayers.String.trim(str).split(this.regExes.parenComma);
            var components = [];
            for(var i=0; i<lines.length; ++i) {
                line = lines[i].replace(this.regExes.trimParens, '$1');
                components.push(this.parse.linestring.apply(this, [line]).geometry);
            }
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.MultiLineString(components)
            );
        },
        
        /**
         * Return a polygon feature given a polygon WKT fragment.
         * @param {String} A WKT fragment representing the polygon
         * @returns {<OpenLayers.Feature.Vector>} A polygon feature
         * @private
         */
        'polygon': function(str) {
            var ring, linestring, linearring;
            var rings = OpenLayers.String.trim(str).split(this.regExes.parenComma);
            var components = [];
            for(var i=0; i<rings.length; ++i) {
                ring = rings[i].replace(this.regExes.trimParens, '$1');
                linestring = this.parse.linestring.apply(this, [ring]).geometry;
                linearring = new OpenLayers.Geometry.LinearRing(linestring.components)
                components.push(linearring);
            }
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.Polygon(components)
            );
        },

        /**
         * Return a multipolygon feature given a multipolygon WKT fragment.
         * @param {String} A WKT fragment representing the multipolygon
         * @returns {<OpenLayers.Feature.Vector>} A multipolygon feature
         * @private
         */
        'multipolygon': function(str) {
            var polygon;
            var polygons = OpenLayers.String.trim(str).split(this.regExes.doubleParenComma);
            var components = [];
            for(var i=0; i<polygons.length; ++i) {
                polygon = polygons[i].replace(this.regExes.trimParens, '$1');
                components.push(this.parse.polygon.apply(this, [polygon]).geometry);
            }
            return new OpenLayers.Feature.Vector(
                new OpenLayers.Geometry.MultiPolygon(components)
            );
        },

        /**
         * Return an array of features given a geometrycollection WKT fragment.
         * @param {String} A WKT fragment representing the geometrycollection
         * @returns {Array} An array of OpenLayers.Feature.Vector
         * @private
         */
        'geometrycollection': function(str) {
            // separate components of the collection with |
            str = str.replace(/,\s*([A-Za-z])/g, '|$1');
            var wktArray = OpenLayers.String.trim(str).split('|');
            var components = [];
            for(var i=0; i<wktArray.length; ++i) {
                components.push(OpenLayers.Format.WKT.prototype.read.apply(this,[wktArray[i]]));
            }
            return components;
        }

    },

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