OpacityVariable | API Reference | ArcGIS Maps SDK for JavaScript 4.31

The opacity visual variable defines the opacity of each feature's symbol based on a numeric field value or number returned from an expression. You must specify stops to construct the opacity ramp.

See also

Sample - Add transparency to features based on field values

Examples

const opacityVisualVariable = {
  type: "opacity",
  field: "PERCENTAGE",
  // maps data values to opacity values
  stops: [
    { value: 0, opacity: 0.1 },
    { value: 100, opacity: 1 }
  ]
};
renderer.visualVariables = [ opacityVisualVariable ];

// opacity visual variable with arcade
const opacityVisualVariable = {
  type: "opacity",
  // calculate a value to visualize with opacity
  valueExpression: "( $feature.TOT_VOTES / $feature.REG_VOTERS ) * 100",
  stops: [
    { value: 30, opacity: 0.15 },
    { value: 70, opacity: 0.15 }
  ]
};
renderer.visualVariables = [ opacityVisualVariable ];

Constructors

OpacityVariable Constructor new OpacityVariable(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 Watch for changes topic.

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Type	Summary	Class
String	The name of the class.	Accessor
String	The name of the numeric attribute field that contains the data values used to determine the color/opacity/size/rotation of each feature.	VisualVariable
Object	An object providing options for displaying the visual variable in the Legend.	VisualVariable
String	Name of the numeric attribute field by which to normalize the data.	OpacityVariable
OpacityStop []	An array of objects that defines the opacity to apply to features in a layer in a sequence of stops.	OpacityVariable
String	The visual variable type.	OpacityVariable
String	An Arcade expression following the specification defined by the Arcade Visualization Profile.	VisualVariable
String	The title identifying and describing the associated Arcade expression as defined in the valueExpression property.	VisualVariable

Property Details

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

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

field Inherited Property field String Inherited from VisualVariable

The name of the numeric attribute field that contains the data values used to determine the color/opacity/size/rotation of each feature.

legendOptions Inherited Property legendOptions Objectautocast Inherited from VisualVariable

An object providing options for displaying the visual variable in the Legend.

Properties: showLegend Boolean|null|undefined

Indicates whether to show the visual variable in the legend.

title String|null|undefined

The title describing the visualization of the visual variable in the Legend. This takes precedence over a field alias or valueExpressionTitle.

normalizationField Property normalizationField String

Name of the numeric attribute field by which to normalize the data. If this field is used, then the values in stops should be normalized as percentages or ratios.

stops Property stops OpacityStop[]autocast Autocasts from Object []

An array of objects that defines the opacity to apply to features in a layer in a sequence of stops. You must specify 2 - 8 stops. In most cases, no more than five are needed. Features with data values that fall between the given stops will be assigned opacity values linearly interpolated along the ramp in relation to the stop values. The stops must be listed in ascending order based on the value of the value property in each stop.

type Property type Stringreadonly

The visual variable type.

For OpacityVariable the type is always "opacity".

valueExpression Inherited Property valueExpression String Inherited from VisualVariable

An Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions in visual variables may reference field values using the $feature profile variable and must return a number.

The values returned from this expression are the data used to drive the visualization as defined in the stops. This takes precedence over field. Therefore, this property is typically used as an alternative to field in visual variables.

See also

Arcade - Visualization Profile

valueExpressionTitle Inherited Property valueExpressionTitle String Inherited from VisualVariable

The title identifying and describing the associated Arcade expression as defined in the valueExpression property. This is displayed as the title of the corresponding visual variable in the Legend in the absence of a provided title in the legendOptions property.

Method Overview

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Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
OpacityVariable	Creates a deep clone of the OpacityVariable.	OpacityVariable
*	Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.	OpacityVariable
Boolean	Returns true if a named group of handles exist.	Accessor
	Removes a group of handles owned by the object.	Accessor
Object	Converts an instance of this class to its ArcGIS portal JSON representation.	OpacityVariable

Method Details

addHandles Inherited Method addHandles(handleOrHandles, groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 4.25.

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();

Parameters

handleOrHandles WatchHandle|WatchHandle []

Handles marked for removal once the object is destroyed.

groupKey *

optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

clone Method clone(){OpacityVariable}

Creates a deep clone of the OpacityVariable.

Returns

Type	Description
OpacityVariable	A deep clone of the opacity visual variable that invoked this method.

Example

// Creates a deep clone of the visual variable
let renderer = renderer.visualVariables[0].clone();

fromJSON Method fromJSON(json){*}static

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameter

json Object

A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns

Type	Description
*	Returns a new instance of this class.

hasHandles Inherited Method hasHandles(groupKey){Boolean} Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 4.25.

Returns true if a named group of handles exist.

Parameter

groupKey *

optional

A group key.

Returns

Type	Description
Boolean	Returns `true` if a named group of handles exist.

Example

// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

removeHandles Inherited Method removeHandles(groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 4.25.

Removes a group of handles owned by the object.

Parameter

groupKey *

optional

A group key or an array or collection of group keys to remove.

Example

obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

toJSON Method toJSON(){Object}

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns

Type	Description
Object	The ArcGIS portal JSON representation of an instance of this class.