Method Overview

Method Details

createRenderer(params){Promise<HeatmapRendererResult>}

Generates a HeatmapRenderer that may be applied directly to the layer used to call this method. The renderer represents points as a continuous surface using optimal colors for the indicated basemap.

This method should be called when at least some points are visible in the input view's extent. If no points are visible in the view, then the response will not return a useful visualization.

In most cases you will provide a layer, basemap, and optional field to generate this renderer. This is a scenario in which the statistics and the distribution of the data aren't well known and the user doesn't know what colors to use in the visualization.

The other options are provided for convenience for more involved custom visualization authoring applications. For example, if you already generated statistics in another operation, you can pass the statistics object to the statistics parameter to avoid making an extra call to the server.

Parameters:

Specification:

params Object Input parameters for generating a heatmap visualization based on data returned from a given field. See the table below for details of each parameter. Specification: layer FeatureLayer|CSVLayer|GeoJSONLayer The point layer for which the visualization is generated. view MapView The view instance in which the visualization will be rendered. field String optional The name of the field whose data will be queried for statistics and used for the basis of the data-driven visualization. The value of the field is used as a multiplier in the heatmap, making areas with high field values hotter than areas where the features have low field values. basemap String|Basemap Deprecated since version 4.13. Use view instead. optional Default Value: gray The named string or basemap object of the Esri basemap that will be paired with the output visualization. Determines optimal colors for the output renderer. heatmapScheme HeatmapScheme optional In authoring apps, the user may select a pre-defined heatmap scheme. Pass the scheme object to this property to avoid getting one based on the basemap. statistics HeatmapStatisticsResult optional A statistics object generated from the heatmapStatistics function. If statistics for the field have already been generated, then pass the object here to avoid making a second statistics query to the server. fadeToTransparent Boolean optional Default Value: true Indicates whether to fade the lower color stops to a transparent color to create a fuzzy boundary on the edge of the heatmap. A value of false makes a discrete boundary on the lower color stop. blurRadius Number optional Default Value: 10 The blurRadius in pixels that determines the area of influence of each point. A higher blur radius indicates points have more influence on surrounding points. minRatio Number optional Default Value: 0.01 The minimum ratio used in the HeatmapRenderer.colorStops of the output renderer. maxRatio Number optional Default Value: 1 The maximum ratio used in the HeatmapRenderer.colorStops of the output renderer.

Returns:

Type	Description
Promise<HeatmapRendererResult>	Resolves to an instance of HeatmapRendererResult.

Example:

var earthquakeLayer = new FeatureLayer({
  // url to a point dataset
});

// visualization based on field

var heatmapParams = {
  layer: earthquakeLayer,
  view: view,
  field: "magnitude"
};

// when the promise resolves, apply the renderer to the layer
heatmapRendererCreator.createRenderer(heatmapParams)
  .then(function(response){
    earthquakeLayer.renderer = response.renderer;
  });

Type Definitions

HeatmapRendererResult

The result object of the createRenderer() method. See the table below for details of each property.

Properties:

renderer HeatmapRenderer The renderer object configured to best match the given basemap and the spread of the data. Set this on a layer's renderer property to update its visualization.

scheme HeatmapScheme The color scheme used by the renderer.

defaultValuesUsed Boolean Indicates whether default values are used in the absence of sufficient data and/or statistics from the layer. Default values are typically used when all features have the same field value or no value at all.

statistics HeatmapStatisticsResult Basic statistics returned from a query to the service for data from the given field name.

basemapId String The ID of the basemap used to determine the optimal color stops of the heatmap.

basemapTheme String Indicates whether the average color of the input view's basemap is light or dark.