HeatmapSlider

require(["esri/widgets/smartMapping/HeatmapSlider"], function(HeatmapSlider) { /* code goes here */ });
Class: esri/widgets/smartMapping/HeatmapSlider
Inheritance: HeatmapSlider Widget Accessor
Since: ArcGIS API 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
more detailsWidget
String

The name of the class.

more details
more detailsAccessor
String

The unique ID assigned to the widget when the widget is created.

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more detailsWidget
String

The HeatmapSlider widget's default label.

more details
more detailsHeatmapSlider
HeatmapColorStop[]

The colorStops of the HeatmapRenderer to associate with the slider.

more details
more detailsHeatmapSlider
HeatmapSliderViewModel

The view model for the Heatmap widget.

more details
more detailsHeatmapSlider

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.

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class
String

A utility method used for building the value for a widget's class property.

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more detailsWidget

Destroys the widget instance.

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more detailsWidget
Boolean

Emits an event on the instance.

more details
more detailsWidget
HeatmapSlider

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

more details
more detailsHeatmapSlider
Boolean

Indicates whether there is an event listener on the instance that matches the provided event name.

more details
more detailsWidget
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

more details
more detailsWidget
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

more details
more detailsWidget
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

more details
more detailsWidget
Object

Registers an event handler on the instance.

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more detailsWidget

Widget teardown helper.

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more detailsWidget

This method is primarily used by developers when implementing custom widgets.

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more detailsWidget
Object

This method is primarily used by developers when implementing custom widgets.

more details
more detailsWidget

Renders widget to the DOM immediately.

more details
more detailsWidget

This method is primarily used by developers when implementing custom widgets.

more details
more detailsWidget
Promise

when() may be leveraged once an instance of the class is created.

more details
more detailsWidget

Method Details

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:
var 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;

    var 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.
isFulfilled(){Boolean}inherited
Since: ArcGIS API 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 API 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 API 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:

A event type, or an array of event types, to listen for.

listener Function

The function to call when the event is fired.

Returns:
Type Description
Object Returns an event handler with a remove() method that can 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(handles)inherited

Widget teardown helper. Any handles added to it will be automatically removed when the widget is destroyed.

Parameter:

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.

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 API 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 that may be used to chain additional functions.
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
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
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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