geomtry string 转换_Arcgis for js之WKT和GEOMETRY的相互转换

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:

* {} 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:

* {|Array} A feature or array of features for

* GEOMETRYCOLLECTION WKT.

*/

read: function(wkt) {

var features, type, str;

wkt = wkt.replace(/[nr]/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 - {}

*

* 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(/^ss*/, '').replace(/ss*$/, '');

},

/**

* 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

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

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

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

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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