ArcGIS-JS 投影变换

Projects the geometry

EPSG:4326 投影到 EPSG:3857

webMercatorUtils.geographicToWebMercator()

https://developers.arcgis.com/javascript/latest/api-reference/esri-geometry-support-webMercatorUtils.html#geographicToWebMercator

import * as webMercatorUtils from '@arcgis/core/geometry/support/webMercatorUtils.js'

const geometry3857 = webMercatorUtils.geographicToWebMercator(geometry4326)

EPSG:4490 投影到 EPSG:3857

无法使用 webMercatorUtils.project() 方法

该方法在客户端执行投影计算。

const res = webMercatorUtils.canProject(
	new SpatialReference({ wkid: 4490 }),
	new SpatialReference({ wkid: 3857 }) // SpatialReference.WebMercator
)
console.log('res:', res); // res: false

使用 geometryService.project() 进行投影

https://developers.arcgis.com/javascript/latest/api-reference/esri-rest-geometryService.html#project
https://developers.arcgis.com/javascript/latest/api-reference/esri-rest-support-ProjectParameters.html
https://developers.arcgis.com/javascript/latest/sample-code/widgets-coordinateconversion-custom/

该方法在服务端执行投影计算。

import ProjectParameters from '@arcgis/core/rest/support/ProjectParameters.js'
import * as geometryService from '@arcgis/core/rest/geometryService.js'

const projectParams = new ProjectParameters({
	geometries: [geometry4490],
	outSpatialReference: new SpatialReference({ wkid: 3857 })
})

const URL4GeometryService = 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/Utilities/Geometry/GeometryServer'
geometryService.project(URL4GeometryService, projectParams).then(res => {
	// res is an array of projected geometries.
})

设置 ArcGIS 服务查询数据返回时的空间参考 outSpatialReference

如果使用 ArcGIS 服务，可以在 Query 属性中设置 outSpatialReference 为服务端返回数据时应使用的空间参考。
https://developers.arcgis.com/javascript/latest/api-reference/esri-rest-support-Query.html#outSpatialReference

const featureLayer = new FeatureLayer({
	url: 'http://xxx.xxx.xxx.xxx/server/rest/services/Hosted/RegionBorder/FeatureServer/0'
})
const query = { // autocasts as Query
	where: "1=1",
	returnGeometry: true,
	returnCentroid: true,
	outFields: ['*'],
	outSpatialReference: SpatialReference.WebMercator // 投影转换在服务端返回数据时执行。
}
featureLayer.queryFeatures(query).then(function(results) {
	// ...
})