AlgorithmicColorRamp | API Reference | ArcGIS Maps SDK for JavaScript 4.31

Creates a color ramp for use in a raster renderer. The algorithmic color ramp is defined by specifying two colors and the algorithm used to traverse the intervening color spaces.

There are three algorithms that can be used to define the color values between the from and to colors: 'cie-lab', 'hsv', and 'lab-lch'. There is very little difference between these algorithms when the from and the to colors are of the same or very similar hues. However, when the hues for the from and to colors are different (Hue is different by 40 or more on a 0-360 scale), the algorithms produce different results. The 'hsv' algorithm traverses the hue difference in a purely linear fashion, resulting in a bright ramp where all intermediate colors are represented. For instance, a ramp from red to green would include orange, yellow, and yellow-green. The 'cie-lab' and 'lab-lch' produce a more blended result. Thus, a ramp from dark green to orange would not contain a bright yellow, but instead a more brown and green-gold or green-brown intermediate color. The advantage of the 'cie-lab' algorithm is that the colors of the ramp are visually equidistant, which can produce a better ramp.

Constructors

AlgorithmicColorRamp Constructor new AlgorithmicColorRamp(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 algorithm used to generate the colors between the `fromColor` and `toColor`.	AlgorithmicColorRamp
String	The name of the class.	Accessor
Color	The first color in the color ramp.	AlgorithmicColorRamp
Color	The last color in the color ramp.	AlgorithmicColorRamp
String	A string value representing the color ramp type.	AlgorithmicColorRamp

Property Details

algorithm Property algorithm String

The algorithm used to generate the colors between the fromColor and toColor. Each algorithm uses different methods for generating the intervening colors.

Possible Value	Description
cie-lab	Blends the from and to colors without traversing the intervening hue space.
lab-lch	The hue, saturation, value (hsv) algorithm is a linear traverse of colors between pairs: Color 1 H to Color 2 H, Color 1 S to Color 2 S, and Color 1 V to Color 2 V.
hsv	The lab-lch algorithm is very similar to the cie-lab but does not seek the shortest path between colors.

Possible Values:"cie-lab" |"lab-lch" |"hsv"

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

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

fromColor Property fromColor Color

The first color in the color ramp.

toColor Property toColor Color

The last color in the color ramp.

type Property type Stringreadonly

A string value representing the color ramp type.

For AlgorithmicColorRamp the type is always "algorithmic".

Default Value:"algorithmic"

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
AlgorithmicColorRamp	Creates a deep clone of this object.	AlgorithmicColorRamp
*	Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.	ColorRamp
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.	ColorRamp

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(){AlgorithmicColorRamp}

Creates a deep clone of this object.

Returns

Type	Description
AlgorithmicColorRamp	A deep clone of the AlgorithmicColorRamp instance that invoked this method.

fromJSON Inherited 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 Inherited Method toJSON(){Object} Inherited from ColorRamp

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.