openlayers 地图使用geom空间数据范围内裁剪地图vue项目

一、引用geom数据解析  图层加载所需

// 空间数据解析
import WKT from "ol/format/WKT";//加载图层所需
import TileLayer from "ol/layer/Tile";//加载图层所需
import TileWMS from "ol/source/TileWMS";

geom数据格式 实例

SRID=9526;POLYGON((797058.3926001191 382519.37767676206,797121.8927271194 382498.210967762,797230.3721107448 382749.565637138,797452.6225552456 383122.6288832645,797635.1854203715 383395.15026164055,798170.9677419361 384023.5369350806,798713.3646600633 384744.527960396,799533.5746338166 385809.47800696274,800241.3364660069 386576.77120821585,800763.8895944465 387139.0119160306,801167.3799847607 387582.18988571985,802450.6117178908 388759.5880738496,803568.4785369578 389540.1104682277,804130.7192447726 389950.21545510436,805017.0751841511 390585.21672510693,806664.1097282203 391498.03105073556,807001.4541529091 391656.78136823623,806875.7768182211 391855.219265112,806168.0149860308 391378.9683126101,805585.9304885283 391048.2384844838,804474.6782660239 390373.54963510606,803733.8434510209 389738.54836510355,803370.040640082 389533.49587166525,802827.6437219548 389196.1514469764,802100.0381000768 388587.60856322397,797058.3926001191 382519.37767676206))

二、解析geom数据 （params.geom传进来的geom空间数据，如上格式）

let wktJson= new WKT()
let vectorSourceFeatures = wktJson.readFeature(params.geom.split(";")[1]);

打印解析出来的vectorSourceFeatures 数据格式

三、加载的需要裁剪范围的图层（这里是应用的arcgis图层 图片形式加载）

let croppingLayers= new TileLayer({id: "cropping",source: new TileWMS({url:"arcgis地址+MapServer/export?F:image",params: {VERSION: "1.1.0",F: "image",FORMAT: "png32",token: 账号token信息,// 有的arcgis加载需要账号登录的token信息 ，没有则去掉这一参数信息layers:  "" //图层条件加载 需要加载某一层则写图层"show:图层名称" 加载所有可以不要这个条件}}),zIndex: 3});

四、设置裁剪范围样式

const style = new Style({fill: new Fill({color: 'transparent',}),});

五、裁剪图层

croppingLayers.on("prerender", event => {let vectorContext = getVectorContext(event);event.context.globalCompositeOperation = 'source-over';let ctx = event.context;ctx.save();vectorContext.drawFeature(vectorSourceFeatures, style);// 可以对边界设置一个样式ctx.clip();})croppingLayers.on("postrender", (event) => {let ctx = event.context;ctx.restore();})croppingLayers.setExtent(vectorSourceFeatures.getGeometry().getExtent())

六、最后地图添加croppingLayers这一图层，就可以获取以geom范围内裁剪的某一图层

this.map.addLayer(croppingLayers);