HeatmapSlider

AMD: require(["esri/widgets/smartMapping/HeatmapSlider"], (HeatmapSlider) => { /* code goes here */ });
ESM: import HeatmapSlider from "@arcgis/core/widgets/smartMapping/HeatmapSlider.js";
Class: esri/widgets/smartMapping/HeatmapSlider
Inheritance: HeatmapSlider Widget Accessor
Since: ArcGIS Maps SDK for JavaScript 4.12

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;
});
For information about gaining full control of widget styles, see the Styling topic.
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
Name 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

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.

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.

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;

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
Name 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
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

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;
});

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