AreaMeasurement2DViewModel

属性概述

属性详细信息

geodesicDistanceThreshold Number

当投影坐标系时 (除了 web 墨卡托)，小于此阈值的周长将用平面法计算。否则，面积将以大地测量方式计算。

默认值：100000

示例

// To set the threshold at 10 km
let measurementWidget = new AreaMeasurement2D({
  viewModel: {
    view: view,
    geodesicDistanceThreshold: 10000
  }
});

measurement Objectreadonly

测量面的面积和周长分别以平方米和米为单位。

属性

area Number 面积 (m²)。

perimeter Number 周长 (m)。

geometry Polygon 测量区域。

示例

// After creating and adding the AreaMeasurement2D widget
let measurementWidget = new AreaMeasurement2D({
  view: view
});
view.ui.add(measurementWidget, "top-right");

// Raw measurements (in meters) can be accessed from this property
measurementWidget.watch("viewModel.measurement", function(measurement) {
  console.log(
     "Area: ", measurement.area,
     "Perimeter: ", measurement.perimeter
  );
});

measurementLabel Objectreadonly

此属性返回特定于语言环境的面积和周长表示。面积和周长四舍五入到小数点后两位。面积来源于 measurement 属性 (以平方米为单位) 并转换为用户定义的单位或系统。

属性

area Number 面积 (m²)。

perimeter Number 周长 (m)。

示例

// After creating and adding the AreaMeasurement2D widget
let measurementWidget = new AreaMeasurement2D({
  view: view
});
view.ui.add(measurementWidget, "top-right");

// Measurement labels can be accessed from this property
measurementWidget.watch("viewModel.measurementLabel", function(label) {
  console.log(
     "Area: ", label.area,
     "Perimeter: ", label.perimeter
  );
});

state Stringreadonly

ViewModel 的状态。

值	描述
disabled	尚未准备就绪
ready	准备测量
measuring	测量已开始
measured	测量已完成

可能值："disabled"|"ready"|"measuring"|"measured"

默认值：disabled

示例

// To display the state of the AreaMeasurement2D widget
let measurementWidget = new AreaMeasurement2D({
  view: view
});
measurementWidget.watch("viewModel.state", function(state){
  console.log("Current state: ", state);
});

unit SystemOrAreaUnit

单位系统（英制、公制）或显示面积值的特定单位。可能值在 unitOptions 中列出。

示例

// To create the AreaMeasurement2D widget that displays area in square US feet
let measurementWidget = new AreaMeasurement2D({
  viewModel: {
    view: view,
    unit: "square-us-feet"
  }
});

// To display the current measurement unit
console.log('Current unit: ', measurementWidget.viewModel.unit);

unitOptions SystemOrAreaUnit[]

用于显示面积值的可用单位列表和单位系统 (英制、公制)。默认情况下，包括以下单位：metric、imperial、square-inches、square-feet、square-us-feet、square-yards、square-miles、square-meters、square-kilometers、acres、ares、hectares。可能的 unit 值只能是此列表的子集。

示例

// To display the available units to the console
let measurementWidget = new AreaMeasurement2D({
  view: view
});
console.log('All units: ', measurementWidget.viewModel.unitOptions.join(", "));

view MapView

微件将从中操作的视图。

示例

// To create the AreaMeasurement2D widget with the view property
let measurementWidget = new AreaMeasurement2D({
  viewModel: {
    view: view
  }
});

方法概述

方法详细说明

clear()

起始版本：GeoScene Maps SDK for JavaScript 4.16

清除当前测量。

start()

起始版本：GeoScene Maps SDK for JavaScript 4.16

开始新的测量。

示例

const areaMeasurement2DViewModel = new AreaMeasurement2DViewModel({
  view: view,
  unit: "square-yards"
});

await areaMeasurement2DViewModel.start();