AreaMeasurement2DViewModel

属性概览

属性详情

geodesicDistanceThreshold Number

当坐标系被投影时（除了 web 墨卡托），小于这个阈值的周长将被平面计算。否则，面积将按大地测量计算。

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

此属性返回区域和周长的区域设置特定表示。面积和周长四舍五入到小数点后两位。面积来自 measurement 属性（以平方米为单位）并转换为用户定义的单位/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	说明
disabled	还没有准备好
ready	准备测量
measuring	测量已开始
measured	测量已结束

可能的值:"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

单位制（英制、公制）或用于显示面积值的特定单位。可能的值在 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和单位系统（英制、公制）列表。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
  }
});

方法概览

方法详情

clear()

起始版本：GeoScene API for JavaScript 4.16

清除当前测量。

start()

起始版本：GeoScene API for JavaScript 4.16

开始新的测量。

示例：

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

await areaMeasurement2DViewModel.start();