FlowRenderer | API Reference | ArcGIS Maps SDK for JavaScript

The FlowRenderer allows you to visualize your raster data with animated streamlines. This renderer can be used to visualize flow direction and magnitude information for meteorology and oceanography raster data.

To use this renderer, the source type of your raster dataset must be Vector-UV or Vector-MagDir. The direction of the raster defines the direction of movement, and the magnitude defines the visible length of the streamline.

Known Limitations

The FlowRenderer is only supported with ImageryTileLayer and ImageryLayer.

See also

Example

const renderer = new FlowRenderer({
  density: 1,
  color: [50, 120, 240], // blue
  flowSpeed: 10,
  trailWidth: "2px"
});

Constructors

FlowRenderer Constructor new FlowRenderer(properties)

Parameter

properties Object

optional

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

Example

let renderer = {
  type: "flow",
  color: [50, 120, 240, 1]
}

Property Overview

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

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Type	Summary	Class
AuthoringInfo	Contains metadata about renderers generated from the flowRendererCreator.createRenderer() method, including information for setting UI elements such as sliders and themes.	FlowRenderer
Color	The color of the animated streamlines.	FlowRenderer
String	The name of the class.	Accessor
Number	The density of the streamlines.	FlowRenderer
String	Defines the flow direction of the data.	FlowRenderer
Number	The speed of the animated streamlines, relative to the simulation time.	FlowRenderer
Object\|null\|undefined	An object providing options for displaying the renderer in the Legend.	FlowRenderer
Number	The maximum path length streamlines will travel in points.	FlowRenderer
String	The front cap of the streamline.	FlowRenderer
Number	The approximate visible length of the streamline in points.	FlowRenderer
Number	The width of the streamline trail in points.	FlowRenderer
String	The type of Renderer.	FlowRenderer
VisualVariable []\|null\|undefined	An array of VisualVariable objects.	FlowRenderer

Property Details

authoringInfo Property authoringInfo AuthoringInfoautocast

Contains metadata about renderers generated from the flowRendererCreator.createRenderer() method, including information for setting UI elements such as sliders and themes. This allows the authoring clients to save specific overridable settings so user selections can be remembered the next time they are accessed via the UI.

color Property color Colorautocast

The color of the animated streamlines.

Default Value:[255, 255, 255, 1]

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

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

density Property density Number

The density of the streamlines. This value determines how many streamlines appear in the visualization:

A value less than or equal to 0 means no streamlines will be rendered.
Values between 0 and 1 reduce the number of streamlines.
Values greater than 1 increase the number of streamlines proportionally.

Notes

While density can exceed 1, the effective maximum number of streamlines is constrained by factors such as screen size and trailLength property. At high densities, new streamlines may be discarded to avoid cluttered visualizations and excessive computation time.

`density = 0.1`	`density = 1`	`density = 1.5`

Default Value:0.8

flowRepresentation Property flowRepresentation String

Defines the flow direction of the data. This can be modified to display meteorological (the direction it is flowing from) or climatological data (the direction it is flowing to).

Value	Description	Example
flow-from	Flow from angle.
flow-to	Flow to angle.

Possible Values:"flow-from" |"flow-to"

Default Value:"flow-from"

flowSpeed Property flowSpeed Number

The speed of the animated streamlines, relative to the simulation time. This serves as a multiple of the magnitude from the raster layer. For instance, if the magnitude is 2ms, and the flowSpeed is 10, then the actual speed of the streamline will be 20 pts/s. A speed of 0 will result in no animation.

Default Value:10

legendOptions Property legendOptions Object |null |undefinedautocast

An object providing options for displaying the renderer in the Legend.

Properties: title String|null|undefined

Describes the variable driving the visualization. This is displayed as the title of the corresponding renderer in the Legend.

order String|null|undefined

Since 4.34 Indicates the order in which the legend values are displayed.

Possible Values:"ascending-values"|"descending-values"

Example

renderer.legendOptions = {
  title: "Wind speed",
  order: "descending-values",
};

maxPathLength Property maxPathLength Numberautocast Autocasts from Number|String

The maximum path length streamlines will travel in points. Only a portion of the streamline will be visible at a time depending on the magnitude or UV coming from the raster layer and the defined trailLength. During the course of the animation, the visible streamline will travel to reach the path length defined here, then will restart. This value may be autocast with a string expressing size in points or pixels (e.g. 100px).

Default Value:200

Examples

// width in points
flowRenderer.maxPathLength = 100;

// width in pixels
flowRenderer.maxPathLength = "200px";

// width in points
flowRenderer.maxPathLength = "100pt";

trailCap Property trailCap String Since: ArcGIS Maps SDK for JavaScript 4.24 FlowRenderer since 4.23, trailCap added at 4.24.

The front cap of the streamline. A round cap will only be applied if trailWidth is greater than 4px or 3pt.

Known Limitations

The round trail cap is not supported in 3D SceneView.

Possible Values:"butt" |"round"

Default Value:"butt"

trailLength Property trailLength Number

The approximate visible length of the streamline in points. The streamlines will appear shorter when the trailLength is a smaller number, since they will start to fade before they reach the full maxPathLength.

`trailLength = 20`	`trailLength = 100`	`trailLength = 250`

Default Value:100

trailWidth Property trailWidth Numberautocast Autocasts from Number|String

The width of the streamline trail in points. This value may be autocast with a string expressing size in points or pixels (e.g. 3px).

Default Value:1.5

Examples

// width in points
flowRenderer.trailWidth = 4;

// width in pixels
flowRenderer.trailWidth = "2px";

// width in points
flowRenderer.trailWidth = "4pt";

type Property type Stringreadonly

The type of Renderer.

For FlowRenderer the type is always "flow".

visualVariables Property visualVariables VisualVariable[] |null |undefinedautocast Autocasts from Object []

An array of VisualVariable objects. Each object must indicate the type of visual variable to apply (e.g. ColorVisualVariable), the numeric field from which to drive the visualization, and the visual values to map to the data. The following list identifies each visual variable type that is supported with the FlowRenderer and provides a link to the specification table of each: ColorVisualVariable, OpacityVisualVariable, and SizeVisualVariable. SizeVisualVariable will update the trailWidth property.

When setting fields for the visual variables set on the FlowRenderer, use the Magnitude field. Magnitude will return pixel values from the first band. If the data represents u (zonal) and v (meridional) speed components, values are automatically converted to Magnitude and Direction.

See also

Styles and data visualization

Example

const renderer = new FlowRenderer({
   visualVariables: [{
      type: "color",
      field: "Magnitude",
      stops: [
        { value: 3, color: "#0080ff" },
        { value: 15, color: "#00ff00" }
      ]
    }, {
      type: "opacity",
      field: "Magnitude",
      stops: [
        { value: 1, opacity: 0.5 },
        { value: 8, opacity: 1 }
      ]
   }]
});

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
FlowRenderer	Creates a deep clone of the renderer.	FlowRenderer
*\|null\|undefined	Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.	FlowRenderer
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.	FlowRenderer

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(){FlowRenderer}

Creates a deep clone of the renderer.

Returns

Type	Description
FlowRenderer

Example

// Creates a deep clone of the first layer's renderer
let renderer = view.map.layers.at(0).renderer.clone();

fromJSON Method fromJSON(json){* |null |undefined}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
* \| null \| undefined	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.