1、導入依賴

import FeatureLayer from '@arcgis/core/layers/FeatureLayer'
import { geodesicArea, planarArea, simplify } from '@arcgis/core/geometry/geometryEngine';
import { project, load as projectionLoad } from '@arcgis/core/geometry/projection'

2、初始化project

onMounted(() => {// 第一步：加載投影引擎projectionLoad()
})

3、計算橢球面積、平面面積

const calculateFeatureLayer = async (featureLayer: FeatureLayer) => {const query = featureLayer.createQuery()query.where = '1 = 1'const result = await featureLayer.queryFeatures(query)// 總面積統計let totalGeoArea = 0;let totalPlanarArea = 0;for (const feature of result.features) {if (feature.geometry.type === 'polygon') {let geometry = feature.geometry// 坐標系轉換if (geometry.spatialReference.wkid !== 4326) {geometry = await project(geometry, { wkid: 4326 }) as any}// 簡化多邊形const simplifiedPolygon = simplify(geometry)// 橢球面積const geoArea = geodesicArea(simplifiedPolygon, "square-kilometers")totalGeoArea += geoArea// 平面面積const projectedGeometry = await project(simplifiedPolygon, { wkid: 3857 }) as anyconst planarAreaResult = planarArea(projectedGeometry, "square-kilometers")totalPlanarArea += planarAreaResult}}console.log("橢球面積(平方千米):", totalGeoArea)console.log("毛面積(平方千米):", totalPlanarArea)}