HeatmapSlider

The HeatmapSlider widget is intended for authoring and exploring data-driven visualizations in any layer that can be rendered with a HeatmapRenderer. At a minimum you must set the stops property of the widget. The stops are used to render a color gradient on the track of the slider.

See the image below for a summary of the configurable options available on this slider.

HeatmapSlider with annotations

The fromRendererResult method can be used to conveniently create this slider from the result of the createRenderer method.

const params = {
  layer: layer,
  basemap: map.basemap,
  view: view
};

let rendererResult = null;

heatmapRendererCreator
  .createRenderer(params)
  .then(function(response) {
    rendererResult = response;
    layer.renderer = response.renderer;

    const slider = slider.fromRendererResult(rendererResult);
    colorSlider.container = "slider";
  })
   .catch(function(error) {
     console.log("there was an error: ", error);
   });

This slider should be used to update the colorStops in a HeatmapRenderer. It is the responsibility of the app developer to set up event listeners on this slider to update the renderer's color stops.

// when the user slides the handle(s), update the renderer
// with the updated color stops

slider.on(["thumb-change", "thumb-drag"], function() {
  const renderer = layer.renderer.clone();
  renderer.colorStops = slider.stops;
  layer.renderer = renderer;
});

See also

Constructors

new HeatmapSlider(properties)

Parameter

properties Object

optional

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

Example

const slider = new HeatmapSlider({
  stops: [
    { color: "rgba(63, 40, 102, 0)", ratio: 0 },
    { color: "#472b77", ratio: 0.083 },
    { color: "#4e2d87", ratio: 0.166 },
    { color: "#563098", ratio: 0.249 },
    { color: "#5d32a8", ratio: 0.332 },
    { color: "#6735be", ratio: 0.415 },
    { color: "#7139d4", ratio: 0.498 },
    { color: "#7b3ce9", ratio: 0.581 },
    { color: "#853fff", ratio: 0.664 },
    { color: "#a46fbf", ratio: 0.747 },
    { color: "#c29f80", ratio: 0.83 },
    { color: "#e0cf40", ratio: 0.913 },
    { color: "#ffff00", ratio: 1 }
  ]
});

Property Overview

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

Show inherited properties

Hide inherited properties

Type	Summary	Class
String\|HTMLElement	The ID or node representing the DOM element containing the widget. more details	Widget
String	The name of the class. more details	Accessor
String	The unique ID assigned to the widget when the widget is created. more details	Widget
String	The HeatmapSlider widget's default label. more details	HeatmapSlider
HeatmapColorStop []	The colorStops of the HeatmapRenderer to associate with the slider. more details	HeatmapSlider
HeatmapSliderViewModel	The view model for the Heatmap widget. more details	HeatmapSlider
Boolean	Indicates whether the widget is visible. more details	Widget

Property Details

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.

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 Stringreadonly

The HeatmapSlider widget's default label.

stops HeatmapColorStop []

The colorStops of the HeatmapRenderer to associate with the slider.

Examples

slider.stops = [
  { color: "rgba(63, 40, 102, 0)", ratio: 0 },
  { color: "#472b77", ratio: 0.083 },
  { color: "#4e2d87", ratio: 0.166 },
  { color: "#563098", ratio: 0.249 },
  { color: "#5d32a8", ratio: 0.332 },
  { color: "#6735be", ratio: 0.415 },
  { color: "#7139d4", ratio: 0.498 },
  { color: "#7b3ce9", ratio: 0.581 },
  { color: "#853fff", ratio: 0.664 },
  { color: "#a46fbf", ratio: 0.747 },
  { color: "#c29f80", ratio: 0.83 },
  { color: "#e0cf40", ratio: 0.913 },
  { color: "#ffff00", ratio: 1 }
];

slider.stops = layer.renderer.colorStops;

viewModel HeatmapSliderViewModel

The view model for the Heatmap widget. This class contains all the logic (properties and methods) that controls this widget's behavior. See the esri/widgets/smartMapping/HeatmapSlider/HeatmapliderViewModel class to access all properties and methods on the HeatmapSlider widget.

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

Show inherited methods

Hide inherited methods

Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object. more details	Accessor
String	A utility method used for building the value for a widget's `class` property. more details	Widget
	Destroys the widget instance. more details	Widget
Boolean	Emits an event on the instance. more details	Widget
HeatmapSlider	A convenience function used to create a HeatmapSlider widget instance from the result of the heatmapRendererCreator.createRenderer() method. more details	HeatmapSlider
Boolean	Indicates whether there is an event listener on the instance that matches the provided event name. more details	Widget
Boolean	Returns true if a named group of handles exist. more details	Accessor
Boolean	`isFulfilled()` may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). more details	Widget
Boolean	`isRejected()` may be used to verify if creating an instance of the class is rejected. more details	Widget
Boolean	`isResolved()` may be used to verify if creating an instance of the class is resolved. more details	Widget
Object	Registers an event handler on the instance. more details	Widget
	Adds one or more handles which are to be tied to the lifecycle of the widget. more details	Widget
	This method is primarily used by developers when implementing custom widgets. more details	Widget
	Removes a group of handles owned by the object. more details	Accessor
Object	This method is primarily used by developers when implementing custom widgets. more details	Widget
	Renders widget to the DOM immediately. more details	Widget
	This method is primarily used by developers when implementing custom widgets. more details	Widget
Promise	`when()` may be leveraged once an instance of the class is created. more details	Widget

Method Details

addHandles(handleOrHandles, groupKey)inherited Since: ArcGIS Maps SDK for JavaScript 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.

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 - Custom widget basics (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)} />
  );
}

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

fromHeatmapRendererResult(rendererResult){HeatmapSlider}static

A convenience function used to create a HeatmapSlider widget instance from the result of the heatmapRendererCreator.createRenderer() method.

Parameter

rendererResult HeatmapRendererResult

The result object from the heatmapRendererCreator.createRenderer() method.

Returns

Type	Description
HeatmapSlider	Returns a HeatmapSlider instance. This will not render until you assign it a valid container.

Example

let params = {
  layer: layer,
  basemap: map.basemap,
  field: "POP",
  view: view
};
heatmapRendererCreator
  .createRenderer(params)
  .then(function(response) {
    // set generated renderer on the layer and add it to the map
    rendererResult = response;
    layer.renderer = response.renderer;

    let slider = HeatmapSlider.fromHeatmapRendererResult(response);
    slider.container = "slider";
  });

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.

hasHandles(groupKey){Boolean}inherited Since: ArcGIS Maps SDK for JavaScript 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");
}

isFulfilled(){Boolean}inherited Since: ArcGIS Maps SDK 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 Maps SDK 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 Maps SDK 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.

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(handleOrHandles)inherited Since: ArcGIS Maps SDK for JavaScript 4.24

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

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

this.own(handle); // Handle gets removed when the widget is destroyed.

Parameter

handleOrHandles 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.

removeHandles(groupKey)inherited Since: ArcGIS Maps SDK for JavaScript 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");

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.

when(callback, errback){Promise}inherited Since: ArcGIS Maps SDK 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`.

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
});

Event Overview

Name	Type	Summary	Class
	{index: Number,oldValue: Number,type: "thumb-change",value: Number}	Fires when a user changes the value of a thumb via arrow keys and keyboard editing of the label on the widget. more details	HeatmapSlider
	{index: Number,state: "start"\|"drag",type: "thumb-drag",value: Number}	Fires when a user drags a thumb on the widget. more details	HeatmapSlider

Event Details

thumb-change

Fires when a user changes the value of a thumb via arrow keys and keyboard editing of the label on the widget.

Properties

index Number

The 0-based index of the thumb emitting the event.

oldValue Number

The former value of the thumb before the change was made.

type String

The type of the event.

The value is always "thumb-change".

value Number

The value of the thumb when the event is emitted.

Example

slider.on("thumb-change", function() {
  const renderer = layer.renderer.clone();
  renderer.colorStops = slider.stops;
  layer.renderer = renderer;
});

thumb-drag

Fires when a user drags a thumb on the widget.

Properties

index Number

The 0-based index of the thumb emitting the event.

state String

The state of the drag.

Possible Values:"start"|"drag"

type String

The type of the event.

The value is always "thumb-drag".

value Number

The value of the thumb when the event is emitted.

Example

slider.on("thumb-drag", function() {
  const renderer = layer.renderer.clone();
  renderer.colorStops = slider.stops;
  layer.renderer = renderer;
});

ArcGIS Maps SDK for JavaScriptAPI Reference

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