1、wkt简介
WKT(Well-known text)是一种文本标记语言,用于表示矢量几何对象、空间参照系统及空间参照系统之间的转换。它的二进制表示方式,亦即WKB(well-known-binary)则胜于在传输和在数据库中存储相同的信息。该格式由开放地理空间联盟(OGC)制定。WKT可以表示的几何对象包括:点,线,多边形,TIN(不规则三角网)及多面体。以下为几何WKT字串样例:
POINT(6 10)
LINESTRING(3 4,10 50,20 25)
POLYGON((1 1,5 1,5 5,1 5,1 1),(2 2,2 3,3 3,3 2,2 2))
MULTIPOINT(3.5 5.6, 4.8 10.5)
MULTILINESTRING((3 4,10 50,20 25),(-5 -8,-10 -8,-15 -4))
MULTIPOLYGON(((1 1,5 1,5 5,1 5,1 1),(2 2,2 3,3 3,3 2,2 2)),((6 3,9 2,9 4,6 3)))
GEOMETRYCOLLECTION(POINT(4 6),LINESTRING(4 6,7 10))
POINT ZM (1 1 5 60)
POINT M (1 1 80)
POINT EMPTY
MULTIPOLYGON EMPTY
2、geometry
geometry为Arcgis中的几何对象,包括Extent、Multipoint、Point 、Polygon 、Polyline。
3、相互转换
实现相互转换,封装成了两个js文件,内容如下:
WKTUtil.js
var WKTUtil = function(options){ this.initialize(options); } WKTUtil.prototype = { /** * 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*$/ }; for(var i in options){ this[i] = options[i]; } }, /** * APIMethod: read * Deserialize a WKT string and return a vector feature or an * array of vector features. Supports WKT for POINT, MULTIPOINT, * LINESTRING, MULTILINESTRING, POLYGON, MULTIPOLYGON, and * GEOMETRYCOLLECTION. * * Parameters: * wkt - {String} A WKT string * * Returns: * {<OpenLayers.Feature.Vector>|Array} A feature or array of features for * GEOMETRYCOLLECTION WKT. */ read: function(wkt) { var features, type, str; wkt = wkt.replace(/[\n\r]/g, " "); var matches = this.regExes.typeStr.exec(wkt); if(matches) { type = matches[1].toLowerCase(); str = matches[2]; if(this.parse[type]) { features = this.parse[type].apply(this, [str]); //console.log(features); } } return features; }, /** * Method: extractGeometry * Entry point to construct the WKT for a single Geometry object. * * Parameters: * geometry - {<OpenLayers.Geometry.Geometry>} * * Returns: * {String} A WKT string of representing the geometry */ extractGeometry: function(geometry) { var type = geometry.CLASS_NAME.split('.')[2].toLowerCase(); if (!this.extract[type]) { return null; } if (this.internalProjection && this.externalProjection) { geometry = geometry.clone(); geometry.transform(this.internalProjection, this.externalProjection); } var wktType = type == 'collection' ? 'GEOMETRYCOLLECTION' : type.toUpperCase(); var data = wktType + '(' + this.extract[type].apply(this, [geometry]) + ')'; return data; }, trim: function(str){ return str.replace(/^\s\s*/, '').replace(/\s\s*$/, ''); }, /** * 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 = this.trim(str).split(this.regExes.spaces); return coords;//new esri.geometry.Point(coords[0], coords[1]); }, /** * Return a multipoint feature given a multipoint WKT fragment. * @param {String} str A WKT fragment representing the multipoint * @returns {OpenLayers.Feature.Vector} A multipoint feature * @private */ 'multipoint': function(str) { var point; var points = this.trim(str).split(','); var components = []; for(var i=0, len=points.length; i<len; ++i) { point = points[i].replace(this.regExes.trimParens, '$1'); components.push(this.parse.point.apply(this, [point]).geometry); } return new OpenLayers.Feature.Vector( new OpenLayers.Geometry.MultiPoint(components) ); }, /** * Return a linestring feature given a linestring WKT fragment. * @param {String} str A WKT fragment representing the linestring * @returns {OpenLayers.Feature.Vector} A linestring feature * @private */ 'linestring': function(str) { var points = this.trim(str).split(','); var components = []; for(var i=0, len=points.length; i<len; ++i) { components.push(this.parse.point.apply(this, [points[i]])); } return components//new esri.geometry.Polyline(components); }, /** * Return a multilinestring feature given a multilinestring WKT fragment. * @param {String} str 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, len=lines.length; i<len; ++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} str A WKT fragment representing the polygon * @returns {OpenLayers.Feature.Vector} A polygon feature * @private */ 'polygon': function(str) { var ring, linestring, linearring; var rings = this.trim(str).split(this.regExes.parenComma); var components = []; for(var i=0, len=rings.length; i<len; ++i) { ring = rings[i].replace(this.regExes.trimParens, '$1'); linestring = this.parse.linestring.apply(this, [ring]); components.push(linestring); } return components; } } }mapTran.js
/** *wkt转化成arcgis的Point对象 * @param wkt * @returns {Polyline} * @constructor */ function WktToPoint(wkt,spatialreference){ var wktUtil = new WKTUtil(); var pt = wktUtil.read(wkt); var json = { x:pt[0], y:pt[1], spatialReference: spatialreference } var point = new esri.geometry.Point(json); return point; } /** *wkt转化成arcgis的Polyline对象 * @param wkt * @returns {Polyline} * @constructor */ function WktToPolyline(wkt, spatialreference){ var wktUtil = new WKTUtil(); var points = wktUtil.read(wkt); var json = { paths: [points], spatialReference: spatialreference } var polyline = new esri.geometry.Polyline(json); return polyline; } /** * wkt转化成arcgis的Polygon对象 * @param wkt * @returns {Polygon} * @constructor */ function WktToPolygon(wkt, spatialreference){ var wktUtil = new WKTUtil(); var points = wktUtil.read(wkt); var json = { rings: points, spatialReference: {"wkid":4326} } var polygon = new esri.geometry.Polygon(json); return polygon; } /** * @param geometry */ function PointToWKT(geometry){ console.log(geometry); return "POINT ("+geometry.x+" "+geometry.y+")"; } /** * @param geometry */ function PolygonToWKT(geometry){ var wkt = []; var rings = geometry.rings; for(var i in rings){ var ring = rings[i]; for(var j in ring){ var p = ring[j]; wkt.push(p.join(" ")); } } return "POLYGON (("+wkt.join(",")+"))"; } /** * @param geometry */ function LineToWKT(geometry){ var wkt = []; var paths = geometry.paths; for(var i in paths){ var path = paths[i]; for(var j in path){ var p = path[j]; wkt.push(p.join(" ")); } } return "LINESTRING ("+wkt.join(",")+")"; }使用的时候,直接调用对应的函数即可。
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Arcgis for js之WKT和GEOMETRY的相互转换
原文地址:http://blog.csdn.net/gisshixisheng/article/details/44057453