Measurement

The Measurement widget groups and manages multiple measurement tools and allows you to easily switch between them using the activeTool property. The tools correspond to the measurement widgets for area and distance in 2D (AreaMeasurement2D, DistanceMeasurement2D) and in 3D (AreaMeasurement3D, DirectLineMeasurement3D).

This widget follows a composite pattern that allows developers to configure the UI to best match their specific requirements. The measurement tools, placements, and icons can all be configured, which offers great flexibility to use with tabbed interfaces or other customized UI. See the Measurement widget sample for an example of this flexibility.

For 2D MapViews, distances are computed geodetically for geographic coordinate systems and web mercator. For non-web mercator projected coordinate systems, computations will be performed planimetrically for distances up to the threshold distance defined by the geodesicDistanceThreshold property of the widget's ViewModel. Distances equivalent to and beyond the threshold will be computed geodetically. By default the threshold is set to 100km.

For 3D SceneViews, the mode in which distances are computed is either euclidean or geodesic. In euclidean mode, the distances are measured as straight lines in the ECEF coordinate system. In geodesic mode, the distances are measured as geodesic lines on the WGS84 ellipsoid.

See also:

Example:

// Add the measurement widget to the upper right hand corner
// with the distance tool active
const map = new Map({
  basemap: "hybrid"
});

const view = new MapView({
  container: "viewDiv",
  map: map,
  center: [-71.69, 43.76],
  zoom: 15
});

const measurement = new Measurement({
  view: view,
  activeTool: "distance"
});
view.ui.add(measurement, "top-right");

// Switch between area and distance measurement
function switchTool() {
 const tool = measurement.activeTool === "distance" ? "area" : "distance";
 measurement.activeTool = tool;
}

Constructors

new Measurement(properties)

Parameter:

properties Object

optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.

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Type	Summary	Class
String	more details Specifies the current measurement tool to display.	more details	Measurement
AreaMeasurement2D\|AreaMeasurement3D\|DirectLineMeasurement3D\|DistanceMeasurement2D	more details The measurement widget that is currently being used.	more details	Measurement
SystemOrAreaUnit	more details Unit system (imperial, metric) or specific unit used for displaying the area values.	more details	Measurement
String\|HTMLElement	more details The ID or node representing the DOM element containing the widget.	more details	Widget
String	more details The name of the class.	more details	Accessor
String	more details The widget's default CSS icon class.	more details	Measurement
String	more details The unique ID assigned to the widget when the widget is created.	more details	Widget
String	more details The widget's default label.	more details	Measurement
SystemOrLengthUnit	more details Unit system (imperial, metric) or specific unit used for displaying the distance values.	more details	Measurement
MapView\|SceneView	more details A reference to the MapView or SceneView.	more details	Measurement
MeasurementViewModel	more details The view model for this widget.	more details	Measurement
Boolean	more details Indicates whether the widget is visible.	more details	Widget

Property Details

activeTool String

Specifies the current measurement tool to display. Setting its value to area activates the area measurement tool and it works for both MapView and SceneView. To measure distance in a MapView set the property to distance and in a SceneView set it to direct-line. If this property is not set, the widget will not be displayed.

Possible Values:"area"|"distance"|"direct-line"

Default Value:null

Example:

// To create the Measurement widget with SceneView's direct-line tool active.
const measurement = new Measurement({
  view: view,
  activeTool: "direct-line"
});

// To switch between direct line and area measurement tools
function switchTool() {
 const tool = measurement.activeTool === "direct-line" ? "area" : "direct-line";
 measurement.activeTool = tool;
}

activeWidget AreaMeasurement2D|AreaMeasurement3D|DirectLineMeasurement3D|DistanceMeasurement2Dreadonly

The measurement widget that is currently being used. Use this property to get access to the active widget.

Default Value:null

Example:

// Print the active widget to the console.
const measurement = new Measurement({
  view: view,
  activeTool: "distance"
});
view.ui.add(measurement, "top-right");
console.log("Active Widget: ", measurement.activeWidget);

areaUnit SystemOrAreaUnit

Unit system (imperial, metric) or specific unit used for displaying the area values.

Example:

// To create the Measurement widget that displays area in square US feet
const measurement = new Measurement({
  view: view,
  activeTool: "area",
  unit: "square-us-feet"
});

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

container String|HTMLElement inherited

The ID or node representing the DOM element containing the widget. This property can only be set once. The following examples are all valid use cases when working with widgets.

Examples:

// Create the HTML div element programmatically at runtime and set to the widget's container
const basemapGallery = new BasemapGallery({
  view: view,
  container: document.createElement("div")
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});

// Specify an already-defined HTML div element in the widget's container

const basemapGallery = new BasemapGallery({
  view: view,
  container: basemapGalleryDiv
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});

// HTML markup
<body>
  <div id="viewDiv"></div>
  <div id="basemapGalleryDiv"></div>
</body>

// Specify the widget while adding to the view's UI
const basemapGallery = new BasemapGallery({
  view: view
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});

declaredClass Stringreadonly inherited

The name of the class. The declared class name is formatted as esri.folder.className.

iconClass Stringreadonly

The widget's default CSS icon class.

id String inherited

The unique ID assigned to the widget when the widget is created. If not set by the developer, it will default to the container ID, or if that is not present then it will be automatically generated.

label String

The widget's default label. This property is useful whenever the widget is controlled by another one (e.g. Expand).

linearUnit SystemOrLengthUnit

Unit system (imperial, metric) or specific unit used for displaying the distance values.

Example:

// To create the Measurement widget that displays distance in yards
const measurement = new Measurement({
  view: view,
  activeTool: "distance",
  linearUnit: "yards"
});

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

view MapView|SceneView

A reference to the MapView or SceneView. Set this to link the widget to a specific view.

Example:

// To create the Measurement widget for SceneView with the direct-line tool active.
const measurement = new Measurement({
  view: sceneView,
  activeTool: "direct-line"
});

viewModel MeasurementViewModelautocast

The view model for this widget. This is a class that contains all the logic (properties and methods) that controls this widget's behavior. See the MeasurementViewModel class to access all properties and methods on the widget.

Example:

// Intialize a measurement widget using the view model.
const measurement = new Measurement({
  viewModel: {
    view: view,
    activeTool: "distance",
    unit: "yards"
  }
});

visible Boolean inherited

Indicates whether the widget is visible.

If false, the widget will no longer be rendered in the web document. This may affect the layout of other elements or widgets in the document. For example, if this widget is the first of three widgets associated to the upper right hand corner of the view UI, then the other widgets will reposition when this widget is made invisible. For more information, refer to the CSS display value of "none".

Default Value:true

Example:

// Hides the widget in the view
widget.visible = false;

Method Overview

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Return Type	Summary	Class
String	more details A utility method used for building the value for a widget's `class` property.	more details	Widget
	more details Removes all measurement widgets and associated graphics.	more details	Measurement
	more details Destroys the widget instance.	more details	Widget
Boolean	more details Emits an event on the instance.	more details	Widget
Boolean	more details Indicates whether there is an event listener on the instance that matches the provided event name.	more details	Widget
Boolean	more details `isFulfilled()` may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).	more details	Widget
Boolean	more details `isRejected()` may be used to verify if creating an instance of the class is rejected.	more details	Widget
Boolean	more details `isResolved()` may be used to verify if creating an instance of the class is resolved.	more details	Widget
Object	more details Registers an event handler on the instance.	more details	Widget
	more details Widget teardown helper.	more details	Widget
	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
Object	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
	more details Renders widget to the DOM immediately.	more details	Widget
	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
	more details Starts a new measurement for the active measurement widget.	more details	Measurement
Promise	more details `when()` may be leveraged once an instance of the class is created.	more details	Widget

Method Details

classes(classNames){String}inherited

A utility method used for building the value for a widget's class property. This aids in simplifying CSS class setup.

Parameter:

classNames String|String []|Object

repeatable

The class names.

Returns:

Type	Description
String	The computed class name.

See also:

Guide - Widget development (rendering)

Example:

// .tsx syntax showing how to set CSS classes while rendering the widget

render() {
  const dynamicIconClasses = {
    [CSS.myIcon]: this.showIcon,
    [CSS.greyIcon]: !this.showIcon
  };

  return (
    <div class={classes(CSS.root, CSS.mixin, dynamicIconClasses)} />
  );
}

clear()

Removes all measurement widgets and associated graphics.

destroy()inherited

Destroys the widget instance.

emit(type, event){Boolean}inherited

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters:

type String

The name of the event.

event Object

optional

The event payload.

Returns:

Type	Description
Boolean	`true` if a listener was notified

hasEventListener(type){Boolean}inherited

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter:

type String

The name of the event.

Returns:

Type	Description
Boolean	Returns true if the class supports the input event.

isFulfilled(){Boolean}inherited Since: ArcGIS API for JavaScript 4.19

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns:

Type	Description
Boolean	Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected(){Boolean}inherited Since: ArcGIS API for JavaScript 4.19

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns:

Type	Description
Boolean	Indicates whether creating an instance of the class has been rejected.

isResolved(){Boolean}inherited Since: ArcGIS API for JavaScript 4.19

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns:

Type	Description
Boolean	Indicates whether creating an instance of the class has been resolved.

on(type, listener){Object}inherited

Registers an event handler on the instance. Call this method to hook an event with a listener. See the Events summary table for a list of supported events.

Parameters:

type String|String []

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

Returns:

Type Description

Object

Returns an event handler with a remove() method that should be called to stop listening for the event(s).

Property	Type	Description
remove	Function	When called, removes the listener from the event.

Example:

view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

own(handles)inherited

Widget teardown helper. Any handles added to it will be automatically removed when the widget is destroyed.

Parameter:

handles WatchHandle|WatchHandle []

Handles marked for removal once the widget is destroyed.

postInitialize()inherited

This method is primarily used by developers when implementing custom widgets. Executes after widget is ready for rendering.

render(){Object}inherited

This method is primarily used by developers when implementing custom widgets. It must be implemented by subclasses for rendering.

Returns:

Type	Description
Object	The rendered virtual node.

renderNow()inherited

Renders widget to the DOM immediately.

scheduleRender()inherited

This method is primarily used by developers when implementing custom widgets. Schedules widget rendering. This method is useful for changes affecting the UI.

startMeasurement()

Starts a new measurement for the active measurement widget.

Example:

const measurement = new Measurement({
  view: view,
  activeTool: "distance"
});

function measure () {
  measurement.startMeasurement();
}

measure();

when(callback, errback){Promise}inherited Since: ArcGIS API for JavaScript 4.19

when() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters:

callback Function

optional

The function to call when the promise resolves.

errback Function

optional

The function to execute when the promise fails.

Returns:

Type	Description
Promise	Returns a new promise for the result of `callback` that may be used to chain additional functions.

Example:

// Although this example uses the BasemapGallery widget, any class instance that is a promise may use when() in the same way
let bmGallery = new BasemapGallery();
bmGallery.when(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

ArcGIS API for JavaScriptAPI Reference

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