BaseTileLayer | References | ArcGIS Maps SDK for JavaScript

import BaseTileLayer from "@arcgis/core/layers/BaseTileLayer.js";

Inheritance:: BaseTileLayer→Layer→Accessor

Subclasses:: BingMapsLayer

Since: ArcGIS Maps SDK for JavaScript 4.4

This class may be extended to create a custom TileLayer. It is a generic tile layer class designed to work with various tile sources, not just ArcGIS cached map services, which are specifically handled by the TileLayer class. Tile layers are composed of images, such as satellite imagery, that are composed of square tiles mosaicked together in columns and rows, giving the layer the appearance that it is one continuous image. They have several levels of detail (LOD) that permit users to zoom in to any region of the map and load additional tiles that depict features in higher resolution at larger map scales.

Tile layers often provide geographic context for other layers such as FeatureLayer and tend to perform better than other layers, such as MapImageLayer and ImageryLayer, that request and display a single image per view.

You can create a custom tile layer by calling Accessor.createSubclass() on the BaseTileLayer class. You may create a custom tile layer for one of the following reasons:

The source of the images isn't explicitly supported by the ArcGIS Maps SDK for JavaScript
Images need to be preprocessed prior to display in the view

Setting up a custom tile layer

Unlike TileLayer, the BaseTileLayer does not make assumptions about the type of data it retrieves, making it more flexible and capable of working with a wider variety of tile sources. By default, the BaseTileLayer is configured to use the Web Mercator spatial reference. If a custom tile source does not use the Web Mercator spatial reference, the BaseTileLayer must be explicitly configured with three key properties in its constructor to ensure proper alignment with the source. Those properties are tileInfo, spatialReference, and fullExtent.

// set the spatial reference to New Zealand Transverse Mercator
 const spatialReference = new SpatialReference({
   wkid: 2193
});

// create the origin point for the tileInfo
// The upper left corner of the tiling scheme,
const origin = new Point({
  x: -4020900,
  y: 19998100,
  spatialReference
});

// Create LODs based on the source tiles
const tileInfo = new TileInfo({
  spatialReference,
  origin: origin,
  format: "mixed",
  lods: [{
     "level": 0,
     "resolution": 156543.03392799935,
     "scale": 591657527.591552
    },
    {
       "level": 1,
       "resolution": 78271.51696399967,
       "scale": 295828763.795776
     },
     // other LODs
   ]
 });

const MyCustomTileLayer = BaseTileLayer.createSubclass({
  constructor() {
    this.tileInfo = tileInfo;
    this.spatialReference = spatialReference;
    this.fullExtent = new Extent ({
      xmin: -1497310.4689000002,
      ymin: 3678220.3271,
      xmax: 4749968.6755,
      ymax: 7192314.8459,
       spatialReference
    })
   },
   // properties of the custom tile layer
   properties: {
     urlTemplate: null,
   }
});

Request images as they are defined

To request images as they are predefined from a data source, overwrite the getTileUrl() method so it returns the URL for the requested tile for a given level, row and column.

// override getTileUrl()
// generate the tile url for a given level, row and column
getTileUrl: function (level, row, col) {
  return this.urlTemplate.replace("{z}", level).replace("{x}", col).replace("{y}", row);
}

Preprocess images prior to display

If data needs to be preprocessed prior to display, then override the fetchTile() method. For example, if you need to apply a compositing operation to the image returned from the server before the image is displayed then you would override this method.

// override fetchTile() method to process the data returned
// from the server.
fetchTile: function (level, row, col, options) {
  // call getTileUrl method to construct the Url for the image
  // for given level, row and column
  let url = this.getTileUrl(level, row, col);

  // request for the tile based on the url returned from getTileUrl() method.
  // the signal option ensures that obsolete requests are aborted.
  return esriRequest(url, {
    responseType: "image",
    signal: options && options.signal
  })
  .then(function (response) {
    // when esriRequest resolves successfully,
    // process the image that is returned
    let image = response.data;
    let width = this.tileInfo.size[0];
    let height = this.tileInfo.size[0];

    // create a canvas with a filled rectangle
    let canvas = document.createElement("canvas");
    let context = canvas.getContext("2d");
    canvas.width = width;
    canvas.height = height;

    // Apply the color provided by the layer to the fill rectangle
    if (this.tint) {
      context.fillStyle = this.tint.toCss();
      context.fillRect(0, 0, width, height);
      // apply multiply blend mode to canvas' fill color and the tile
      // returned from the server to darken the tile
      context.globalCompositeOperation = "multiply";
    }
    context.drawImage(image, 0, 0, width, height);
    return canvas;
  }.bind(this));
}

See the following samples for examples of how this works:

If the custom tile layer requires loadable resources, then you must load all loadable dependencies on the layer, within the load() method. Add the promise returned from the loadable resource with the addResolvingPromise() method. The layer will then wait for all of dependencies to finish loading before it is considered loaded.

// Override load method
load: function () {
 // multiply property is an array of ArcGIS cached map services
 this.multiply.forEach(function (layer) {
   // loop through each tile layers and call
   // load method on each layer
   let promise = layer.load();

   // add the promise of each load() method to addResolvingPromise()
   // the custom tile layer will be loaded when every promise is resolved
   this.addResolvingPromise(promise);
 }, this);
}

The layer is responsible for generating the tile URL and fetching tiles from the server for the level, row, and column provided by the LayerView. The LayerView displays the fetched tiles.

See also

Properties

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

Property	Type	Class
`blendMode` inherited	`BlendMode`	BlendLayer
`declaredClass` readonly inherited	`string`	Accessor
`effect` inherited	`Effect \| null \| undefined`	BlendLayer
`fullExtent` inherited	`Extent \| null \| undefined`	Layer
`id` inherited	`string`	Layer
`listMode` inherited	`LayerListMode`	Layer
`loaded` readonly inherited	`boolean`	Layer
`loadError` readonly inherited	`EsriError \| null \| undefined`	LoadableMixin
`loadStatus` readonly inherited	`"not-loaded" \| "loading" \| "failed" \| "loaded"`	LoadableMixin
`loadWarnings` readonly inherited	`any[]`	LoadableMixin
`maxScale` inherited	`number`	ScaleRangeLayer
`minScale` inherited	`number`	ScaleRangeLayer
`opacity` inherited	`number`	Layer
`parent` inherited	`Map \| Basemap \| Ground \| GroupLayer \| CatalogDynamicGroupLayer \| CatalogLayer \| null \| undefined`	Layer
`persistenceEnabled` readonly inherited	`boolean`	Layer
`refreshInterval` inherited	`number`	RefreshableLayer
`spatialReference`	`SpatialReference`
`tileInfo`	`TileInfo`
`title` inherited	`string \| null \| undefined`	Layer
`type` readonly	`"base-tile" \| "bing-maps"`
`uid` readonly inherited	`string`	IdentifiableMixin
`visibilityTimeExtent` inherited	`TimeExtent \| null \| undefined`	Layer
`visible` inherited	`boolean`	Layer

blendMode

inherited Property

Type: BlendMode

Inherited from: BlendLayer

Since: ArcGIS Maps SDK for JavaScript 4.16

Blend modes are used to blend layers together to create an interesting effect in a layer, or even to produce what seems like a new layer. Unlike the method of using transparency which can result in a washed-out top layer, blend modes can create a variety of very vibrant and intriguing results by blending a layer with the layer(s) below it.

When blending layers, a top layer is a layer that has a blend mode applied. All layers underneath the top layer are background layers. The default blending mode is normal where the top layer is simply displayed over the background layer. While this default behavior is perfectly acceptable, the use of blend modes on layers open up a world of endless possibilities to generate creative maps.

The layers in a GroupLayer are blended together in isolation from the rest of the map.

In the following screenshots, the vintage shaded relief layer is displayed over a firefly world imagery layer. The color blend mode is applied to the vintage shaded relief and the result looks like a new layer.

Known Limitations

In 3D SceneViews, the blendMode is supported on BaseTileLayer, ImageryTileLayer, OpenStreetMapLayer, TileLayer, VectorTileLayer, WCSLayer, WebTileLayer, WMTSLayer and GroupLayer.
When working with GroupLayers in a 3D SceneView, the blendMode is only applied to the sublayers that support it.
The blendMode is not supported in the Legend.
See print for known printing limitations.

The following factors will affect the blend result:

Order of all layers
Layer opacity
Opacity of features in layers
Visibility of layers
By default, the very bottom layer in a map is drawn on a transparent background. You can change the MapView's background color.

Blend mode	Description
normal	The top layer is displayed over the background layer. The data of the top layer block the data of background layer where they overlap.
average	Takes the mathematical average of top and background layers. Result of `average` blend mode is often similar to the effect of setting the layer's opacity to 50%.

Lighten blend modes:

The following blend modes create lighter results than all layers. In lighten blend modes, pure black colors in the top layer become transparent allowing the background layer to show through. White in the top layer will stay unchanged. Any color that is lighter than pure black is going to lighten colors in the top layer to varying degrees all way to pure white.

Lighten blend modes can be useful when lightening dark colors of the top layer or removing black colors from the result. The plus, lighten and screen modes can be used to brighten layers that have faded or dark colors on a dark background.

Blend mode	Description
lighten	Compares top and background layers and retains the lighter color. Colors in the top layer become transparent if they are darker than the overlapping colors in the background layer allowing the background layer to show through completely. Can be thought of as the opposite of `darken` blend mode.
lighter	Colors in top and background layers are multiplied by their alphas (layer opacity and layer's data opacity. Then the resulting colors are added together. All overlapping midrange colors are lightened in the top layer. The opacity of layer and layer's data will affect the blend result.
plus	Colors in top and background layers are added together. All overlapping midrange colors are lightened in the top layer. This mode is also known as `add` or `linear-dodge`.
screen	Multiplies inverted colors in top and background layers then inverts the colors again. The resulting colors will be lighter than the original color with less contrast. Screen can produce many different levels of brightening depending on the luminosity values of the top layer. Can be thought of as the opposite of the `multiply` mode.
color-dodge	Divides colors in background layer by the inverted top layer. This lightens the background layer depending on the value of the top layer. The brighter the top layer, the more its color affects the background layer. Decreases the contrast between top and background layers resulting in saturated mid-tones and blown highlights.

Darken blend modes:

The following blend modes create darker results than all layers. In darken blend modes, pure white in the top layer will become transparent allowing the background layer to show through. Black in the top layer will stay unchanged. Any color that is darker than pure white is going to darken a top layer to varying degrees all the way to pure black.

The multiply blend mode is often used to highlight shadows, show contrast, or accentuate an aspect of a map. For example, you can use multiply blend mode on a topographic map displayed over hillshade when you want to have your elevation show through the topographic layer. See the intro to layer blending sample.

The multiply and darken modes can be used to have dark labels of the basemap to show through top layers. See the darken blending sample.

The color-burn mode works well with colorful top and background layers since it increases saturation in mid-tones. It increases the contrast by tinting pixels in overlapping areas in top and bottom layers more towards the top layer color. Use this blend mode, when you want an effect with more contrast than multiply or darken.

The following screenshots show how the multiply blend mode used for creating a physical map of the world that shows both boundaries and elevation. multiply-blend

Blend mode	Description
darken	Emphasizes the darkest parts of overlapping layers. Colors in the top layer become transparent if they are lighter than the overlapping colors in the background layer, allowing the background layer to show through completely.
multiply	Emphasizes the darkest parts of overlapping layers by multiplying colors of the top layer and the background layer. Midrange colors from top and background layers are mixed together more evenly.
color-burn	Intensifies the dark areas in all layers. It increases the contrast between top and background layers, by tinting colors in overlapping area towards the top color. To do this it inverts colors of the background layer, divides the result by colors of the top layer, then inverts the results.

Contrast blend modes:

The following blend modes create contrast by both lightening the lighter areas and darkening the darker areas in the top layer by using lightening or darkening blend modes to create the blend. The contrast blend modes will lighten the colors lighter than 50% gray ([128,128,128]), and darken the colors darker than 50% gray. 50% gray will be transparent in the top layer. Each mode can create a variety of results depending on the colors of top and background layers being blended together. The overlay blend mode makes its calculations based on the brightness of the colors in the background layer while all of the other contrast blend modes make their calculations based on the brightness of the top layer. Some of these modes are designed to simulate the effect of shining a light through the top layer, effectively projecting upon the layers beneath it.

Contrast blend modes can be used to increase the contrast and saturation to have more vibrant colors and give a punch to your layers. For example, you can duplicate a layer and set overlay blend mode on the top layer to increase the contrast and tones of your layer. You can also add a polygon layer with a white fill symbol over a dark imagery layer and apply soft-light blend mode to increase the brightness in the imagery layer.

The following screenshots show an effect of the overlay blend mode on a GraphicsLayer. The left image shows when the buffer graphics layer has the normal blend mode. As you can see, the gray color for the buffer polygon is blocking the intersecting census tracts. The right image shows when the overlay blend mode is applied to the buffer graphics layer. The overlay blend mode darkens or lightens the gray buffer polygon depending on the colors of the background layer while the census tracts layer is shining through. See this in action.

Normal blend mode	Overlay blend mode

Blend mode	Description
overlay	Uses a combination of `multiply` and `screen` modes to darken and lighten colors in the top layer with the background layer always shining through. The result is darker color values in the background layer intensify the top layer, while lighter colors in the background layer wash out overlapping areas in the top layer.
soft-light	Applies a half strength `screen` mode to lighter areas and half strength `multiply` mode to darken areas of the top layer. You can think of the `soft-light` as a softer version of the `overlay` mode.
hard-light	Multiplies or screens the colors, depending on colors of the top layer. The effect is similar to shining a harsh spotlight on the top layer.
vivid-light	Uses a combination of `color-burn` or `color-dodge` by increasing or decreasing the contrast, depending on colors in the top layer.

Component blend modes:

The following blend modes use primary color components, which are hue, saturation and luminosity to blend top and background layers. You can add a feature layer with a simple renderer over any layer and set hue, saturation, color or luminosity blend mode on this layer. With this technique, you create a brand new looking map.

The following screenshots show where the topo layer is blended with world hillshade layer with luminosity blend mode. The result is a drastically different looking map which preserves the brightness of the topo layer while adapting the hue and saturation of the hillshade layer.

Blend mode	Description
hue	Creates an effect with the hue of the top layer and the luminosity and saturation of the background layer.
saturation	Creates an effect with the saturation of the top layer and the hue and luminosity of the background layer. 50% gray with no saturation in the background layer will not produce any change.
luminosity	Creates effect with the luminosity of the top layer and the hue and saturation of the background layer. Can be thought of as the opposite of `color` blend mode.
color	Creates an effect with the hue and saturation of the top layer and the luminosity of the background layer. Can be thought of as the opposite of `luminosity` blend mode.

Composite blend modes:

The following blend modes can be used to mask the contents of top, background or both layers.

Destination modes are used to mask the data of the top layer with the data of the background layer.
Source modes are used to mask the data of the background layer with the data of the top layer.

The destination-in blend mode can be used to show areas of focus such as earthquakes, animal migration, or point-source pollution by revealing the underlying map, providing a bird's eye view of the phenomenon. Check out multiple blending and groupLayer blending samples to see composite blend modes in action.

The following screenshots show feature and imagery layers on the left side on their own in the order they are drawn in the view. The imagery layer that contains land cover classification rasters. The feature layer contains 2007 county crops data. The right image shows the result of layer blending where destination-in blendMode is set on the imagery layer. As you can see, the effect is very different from the original layers. The blended result shows areas of cultivated crops only (where both imagery and feature layers overlap).

Blend mode	Description
destination-over	Destination/background layer covers the top layer. The top layer is drawn underneath the destination layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-atop	Destination/background layer is drawn only where it overlaps the top layer. The top layer is drawn underneath the background layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-in	Destination/background layer is drawn only where it overlaps with the top layer. Everything else is made transparent.
destination-out	Destination/background layer is drawn where it doesn't overlap the top layer. Everything else is made transparent.
source-atop	Source/top layer is drawn only where it overlaps the background layer. You will see the background layer peek through where the source layer is transparent or has no data.
source-in	Source/top layer is drawn only where it overlaps with the background layer. Everything else is made transparent.
source-out	Source/top layer is drawn where it doesn't overlap the background layer. Everything else is made transparent.
xor	Top and background layers are made transparent where they overlap. Both layers are drawn normal everywhere else.

Invert blend modes:

The following blend modes either invert or cancel out colors depending on colors of the background layer. These blend modes look for variations between top and background layers. For example, you can use difference or exclusion blend modes on two imagery layers of forest covers to visualize how forest covers changed from one year to another.

The invert blend mode can be used to turn any light basemap into a dark basemap to accommodate those who work in low-light conditions. The following screenshots show how setting the invert blend mode set on a feature layer with a simple renderer turns the world Hillshade into a dark themed basemap in no time.

Blend mode	Description
difference	Subtracts the darker of the overlapping colors from the lighter color. When two pixels with the same value are subtracted, the result is black. Blending with black produces no change. Blending with white inverts the colors. This blending mode is useful for aligning layers with similar content.
exclusion	Similar to the `difference` blend mode, except that the resulting image is lighter overall. Overlapping areas with lighter color values are lightened, while darker overlapping color values become transparent.
minus	Subtracts colors of the top layer from colors of the background layer making the blend result darker. In the case of negative values, black is displayed.
invert	Inverts the background colors wherever the top and background layers overlap. The invert blend mode inverts the layer similar to a photographic negative.
reflect	This blend mode creates effects as if you added shiny objects or areas of light in the layer. Black pixels in the background layer are ignored as if they were transparent.

See also

Layer blending samples

Default value: "normal"

declaredClass

readonlyinherited Property

Type: string

Inherited from: Accessor

Since: ArcGIS Maps SDK for JavaScript 4.7

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

effect

inherited Property

Type: Effect | null | undefined

Inherited from: BlendLayer

Since: ArcGIS Maps SDK for JavaScript 4.18

Effect provides various filter functions that can be performed on the layer to achieve different visual effects similar to how image filters work. This powerful capability allows you to apply css filter-like functions to layers to create custom visual effects to enhance the cartographic quality of your maps. This is done by applying the desired effect to the layer's effect property as a string or an array of objects to set scale dependent effects.

Notes

Set featureEffect property on a layer if different effects need to be applied features that meet or fail a specified filter. If all of the following four properties are applied, then they will be applied in this order: featureEffect, effect, opacity and blendMode.

Known Limitations

The effect is not supported in 3D SceneViews.
The effect cannot be applied to a layer with a heatmap renderer.
The effect is not supported in layers with FeatureLayer.featureReduction of type cluster enabled.
See print for known printing limitations.

See also

Examples

// the following effect will be applied to the layer at all scales
// brightness will be applied first, then hue-rotate followed by contrast
// changing order of the effects will change the final result
layer.effect = "brightness(5) hue-rotate(270deg) contrast(200%)";

// set a scale dependent bloom effect on the layer
layer.effect = [
  {
    scale: 36978595,
    value: "drop-shadow(3px, 3px, 4px)"
  },
  {
    scale: 18489297,
    value: "drop-shadow(2px, 2px, 3px)"
  },
  {
    scale: 4622324,
    value: "drop-shadow(1px, 1px, 2px)"
  }
];

fullExtent

autocast inherited Property

Type: Extent | null | undefined

Inherited from: Layer

The full extent of the layer. By default, this is worldwide. This property may be used to set the extent of the view to match a layer's extent so that its features appear to fill the view. See the sample snippet below.

The fullExtent property is always null for GroupLayer.

Example

// Once the layer loads, set the view's extent to the layer's full extent
layer.when(function(){
  view.extent = layer.fullExtent;
});

id

inherited Property

Type: string

Inherited from: Layer

The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.

listMode

inherited Property

Type: LayerListMode

Inherited from: Layer

Indicates how the layer should display in the Layer List component. The possible values are listed below.

Value	Description
show	The layer is visible in the table of contents.
hide	The layer is hidden in the table of contents.
hide-children	If the layer is a GroupLayer, BuildingSceneLayer, KMLLayer, MapImageLayer, SubtypeGroupLayer, TileLayer, or WMSLayer, hide the children layers from the table of contents.

Default value: "show"

loaded

readonlyinherited Property

Type: boolean

Inherited from: Layer

Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.

Default value: false

loadError

readonlyinherited Property

Type: EsriError | null | undefined

Inherited from: LoadableMixin

The Error object returned if an error occurred while loading.

loadStatus

readonlyinherited Property

Type: "not-loaded" | "loading" | "failed" | "loaded"

Inherited from: LoadableMixin

Represents the status of a load() operation.

Value	Description
not-loaded	The object's resources have not loaded.
loading	The object's resources are currently loading.
loaded	The object's resources have loaded without errors.
failed	The object's resources failed to load. See loadError for more details.

Default value: "not-loaded"

loadWarnings

readonlyinherited Property

Type: any[]

Inherited from: LoadableMixin

A list of warnings which occurred while loading.

maxScale

inherited Property

Type: number

Inherited from: ScaleRangeLayer

The maximum scale (most zoomed in) at which the layer is visible in the view. If the map is zoomed in beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a maximum scale. The maxScale value should always be smaller than the minScale value, and greater than or equal to the service specification.

Default value: 0

Examples

// The layer will not be visible when the view is zoomed in beyond a scale of 1:1,000
layer.maxScale = 1000;

// The layer's visibility is not restricted to a maximum scale.
layer.maxScale = 0;

minScale

inherited Property

Type: number

Inherited from: ScaleRangeLayer

The minimum scale (most zoomed out) at which the layer is visible in the view. If the map is zoomed out beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a minimum scale. The minScale value should always be larger than the maxScale value, and lesser than or equal to the service specification.

Default value: 0

Examples

// The layer will not be visible when the view is zoomed out beyond a scale of 1:3,000,000
layer.minScale = 3000000;

// The layer's visibility is not restricted to a minimum scale.
layer.minScale = 0;

opacity

inherited Property

Type: number

Inherited from: Layer

The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.

Known Limitations

In a 3D SceneView, modifying opacity is not supported for DimensionLayer, GaussianSplatLayer, IntegratedMesh3DTilesLayer, IntegratedMeshLayer, LineOfSightLayer, PointCloudLayer, ViewshedLayer, and VoxelLayer.

Default value: 1

Example

// Makes the layer 50% transparent
layer.opacity = 0.5;

parent

inherited Property

Type: Map | Basemap | Ground | GroupLayer | CatalogDynamicGroupLayer | CatalogLayer | null | undefined

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.27

The parent to which the layer belongs.

persistenceEnabled

readonlyinherited Property

Type: boolean

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.28

When true, the layer can be persisted. This property only has an effect for layers that are part of the WebMap or WebScene spec.

Default value: false

refreshInterval

inherited Property

Type: number

Inherited from: RefreshableLayer

Since: ArcGIS Maps SDK for JavaScript 4.6

Refresh interval of the layer in minutes. Value of 0 indicates no refresh.

See also

Default value: 0

Example

// the layer will be refreshed every minute.
layer.refreshInterval = 1;

spatialReference

autocast Property

Type: SpatialReference

The spatial reference of the layer.

Default value: {@link geometry/SpatialReference#WebMercator}

tileInfo

autocast Property

Type: TileInfo

The tiling scheme information for the layer.

title

inherited Property

Type: string | null | undefined

Inherited from: Layer

The title of the layer used to identify it in places such as the Layer List component.

If the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

type

readonly Property

Type: "base-tile" | "bing-maps"

For BaseTileLayer the type is base-tile.

Default value: "base-tile"

uid

readonlyinherited Property

Type: string

Inherited from: IdentifiableMixin

Since: ArcGIS Maps SDK for JavaScript 4.33

An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.

visibilityTimeExtent

autocast inherited Property

Type: TimeExtent | null | undefined

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.30

Specifies a fixed time extent during which a layer should be visible. This property can be used to configure a layer that does not have time values stored in an attribute field to work with time. Once configured, the TimeSlider widget will display the layer within the set time extent. In the case that only one of the TimeExtent.start or TimeExtent.end date values are available, the layer remains visible indefinitely in the direction where there is no time value.

Aerial imagery can capture seasonal variations in vegetation, water bodies, and land use patterns. For example, in agricultural regions, aerial imageries taken during different growing seasons provide insights into crop health and productivity. Defining a fixed time extent on imageries from specific time periods provides temporal context and facilitates focused analysis based on specific time periods or events.

See also

Sample - GraphicsLayer with visibilityTimeExtent

visible

inherited Property

Type: boolean

Inherited from: Layer

Indicates if the layer is visible in the View. When false, the layer may still be added to a Map instance that is referenced in a view, but its features will not be visible in the view.

Default value: true

Example

// The layer is no longer visible in the view
layer.visible = false;

// Watch for changes in the layer's visibility
// and set the visibility of another layer when it changes
reactiveUtils.watch(
  () => layer.visible,
  (visible) => {
    if (visible) {
      anotherLayer.visible = true;
    } else {
      anotherLayer.visible = false;
    }
  }
);

Methods

Method	Signature	Class
`fromArcGISServerUrl` inherited static	`fromArcGISServerUrl(params: string \| FromArcGISServerUrlParameters): Promise<Layer>`	Layer
`fromPortalItem` inherited static	`fromPortalItem(params: LayerFromPortalItemParameters): Promise<Layer>`	Layer
`addResolvingPromise`	`addResolvingPromise<U, V extends EsriPromiseMixin>(promiseToLoad: PromiseLike<U> \| V \| PromiseLike<V> \| null \| undefined): void`
`cancelLoad` inherited	`cancelLoad(): this`	LoadableMixin
`createLayerView` inherited	`createLayerView<T extends LayerView = LayerView>(view: View<T>, options?: AbortOptions): Promise<T>`	Layer
`destroy` inherited	`destroy(): void`	Layer
`emit` inherited	`emit<Type extends EventNames<this>>(type: Type, event?: this["@eventTypes"][Type]): boolean`	EventedMixin
`fetchAttributionData` inherited	`fetchAttributionData(): Promise<any>`	Layer
`fetchTile`	`fetchTile(level: number, row: number, col: number, options?: AbortOptions): Promise<HTMLImageElement \| HTMLCanvasElement>`
`getTileBounds`	`getTileBounds(level: number, row: number, column: number, out?: [ number, number, number, number ]): [ number, number, number, number ]`
`getTileUrl`	`getTileUrl(level: number, row: number, col: number): string \| null \| undefined`
`hasEventListener` inherited	`hasEventListener<Type extends EventNames<this>>(type: Type): boolean`	EventedMixin
`isFulfilled` inherited	`isFulfilled(): boolean`	EsriPromiseMixin
`isRejected` inherited	`isRejected(): boolean`	EsriPromiseMixin
`isResolved` inherited	`isResolved(): boolean`	EsriPromiseMixin
`load` inherited	`load(options?: AbortOptions \| null \| undefined): Promise<this>`	LoadableMixin
`on` inherited	`on<Type extends EventNames<this>>(type: Type, listener: EventedCallback<this["@eventTypes"][Type]>): ResourceHandle`	EventedMixin
`refresh` inherited	`refresh(): void`	RefreshableLayer
`when` inherited	`when<TResult1 = this, TResult2 = never>(onFulfilled?: OnFulfilledCallback<this, TResult1> \| null \| undefined, onRejected?: OnRejectedCallback<TResult2> \| null \| undefined): Promise<TResult1 \| TResult2>`	EsriPromiseMixin

fromArcGISServerUrl

inheritedstatic Method

Signature: fromArcGISServerUrl (params: string | FromArcGISServerUrlParameters): Promise<Layer>

Inherited from: Layer

Creates a new layer instance from an ArcGIS Server URL. Depending on the URL, the returned layer type may be a BuildingSceneLayer, CatalogLayer, ElevationLayer, FeatureLayer, GroupLayer, ImageryLayer, ImageryTileLayer, IntegratedMeshLayer, KnowledgeGraphLayer, MapImageLayer, OrientedImageryLayer, PointCloudLayer, SceneLayer, StreamLayer, SubtypeGroupLayer, TileLayer, or VideoLayer.

This is useful when you work with various ArcGIS Server URLs, but you don't necessarily know which layer type(s) they create. This method creates the appropriate layer type for you. In case of a feature service or a scene service, when the URL points to the service and the service has multiple layers, the returned promise will resolve to a GroupLayer.

Beginning with version 4.17, it is possible to load tables from hosted feature services. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific URL types.

URL	Returns
Feature service with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature service with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature service with more than one layer(s)/table(s)	GroupLayer with layers and tables.
Layers with type other than "Feature Layer" are discarded, e.g. Utility Network Layers	N/A

See also

FeatureLayer.isTable

Parameters

Parameter	Type	Description	Required
params	`string \| FromArcGISServerUrlParameters`	Input parameters for creating the layer.

Returns: Promise<Layer>
Returns a promise that resolves to the new Layer instance.

Examples

// This snippet shows how to add a feature layer from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl,
  properties: {
    // set any layer properties here
    popupTemplate: new PopupTemplate()
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});

// This snippet shows how to add a table from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl
}).then(function(layer){
  // Load the table before it can be used
  layer.load().then(function() {
    // Check that it is the right type
    if (layer.isTable) {
      // Add table to map's tables collection
      map.tables.add(layer);
    }
  });
});

fromPortalItem

inheritedstatic Method

Signature: fromPortalItem (params: LayerFromPortalItemParameters): Promise<Layer>

Inherited from: Layer

Creates a new layer instance of the appropriate layer class from an ArcGIS Online or ArcGIS Enterprise portal item. If the item points to a feature service with multiple layers, then a GroupLayer is created. If the item points to a service with a single layer, then it resolves to a layer of the same type of class as the service.

Note

At version 4.29, MediaLayer can be loaded from portal items.
At version 4.28, GroupLayer and OrientedImageryLayer can be loaded from portal items.
At version 4.25, CSVLayer and GeoJSONLayer can be loaded from CSV and GeoJSON portal items respectively.
At version 4.17, it is possible to load tables from feature service items hosted in ArcGIS Online and ArcGIS Enterprise. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific item types.

Item(s)	Returns
Feature service with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature service with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature service with more than one layer(s)/table(s)	GroupLayer with layers and tables.
Feature collection with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature collection with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature collection with more than one layer(s)/table(s)	GroupLayer with layers and tables.

Known Limitations

This method does not currently work with OGCFeatureServer portal items.

See also

Parameters

Parameter	Type	Description	Required
params	`LayerFromPortalItemParameters`	The parameters for loading the portal item.

Returns: Promise<Layer>
Returns a promise which resolves to the new layer instance.

Examples

// Create a layer from a specified portal item and add to the map
Layer.fromPortalItem({
  portalItem: {  // autocasts new PortalItem()
    id: "8444e275037549c1acab02d2626daaee"
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});

// Create a table from a specified portal item and add it to the map's tables collection
Layer.fromPortalItem({
  portalItem: { // autocasts new PortalItem()
    id: "123f4410054b43d7a0bacc1533ceb8dc" // This is a hosted table stored in a feature service
  }
}).then(function(layer) {
  // Necessary to load the table in order for it to be read correctly
  layer.load().then(function() {
    // Confirm this reads as a table
    if (layer.isTable) {
      // Add the new table to the map's table collection
      map.tables.add(layer);
    }
  });
});

addResolvingPromise

Method

Signature: addResolvingPromise <U, V extends EsriPromiseMixin>(promiseToLoad: PromiseLike<U> | V | PromiseLike<V> | null | undefined): void

Type parameters: <U, V extends EsriPromiseMixin>

Adds a Promise to the layer's loadable chain. This is typically used in the load() method to ensure that all loadable resources required for the layer to function are loaded prior to this layer resolving and becoming loaded.

See also

Sample - Custom BlendLayer

Parameters

Parameter	Type	Description	Required
promiseToLoad	`PromiseLike \| V \| PromiseLike \| null \| undefined`	A promise that must resolve for the layer to resolve and move from the `loading` status to being loaded.

Returns: void

Example

// The requiredLayer must load() prior to the MyCustomTileLayer
// resolving and moving to the "loaded" status.
let MyCustomTileLayer = BaseTileLayer.createSubclass({
  load: function() {
    let promise = this.requiredLayer.load();
    this.addResolvingPromise(promise);
  }
});

cancelLoad

inherited Method

Signature: cancelLoad (): this

Inherited from: LoadableMixin

Cancels a load() operation if it is already in progress.

Returns: this

createLayerView

inherited Method

Signature: createLayerView <T extends LayerView = LayerView>(view: View<T>, options?: AbortOptions): Promise<T>

Type parameters: <T extends LayerView = LayerView>

Inherited from: Layer

Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it. This method is used internally and there is no use case for invoking it directly.

See also

Sample - Custom WebGL layer view

Parameters

Parameter	Type	Description	Required
view	`View`	The parent view.
options	`AbortOptions`	An object specifying additional options. See the object specification table below for the required properties of this object.

Returns: Promise
Resolves with a LayerView instance.

destroy

inherited Method

Signature: destroy (): void

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.17

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer). The layer can no longer be used once it has been destroyed.

The destroyed layer will be removed from its parent object like Map, WebMap, WebScene, Basemap, Ground, or GroupLayer.

See also

Returns: void

emit

inherited Method

Signature: emit <Type extends EventNames<this>>(type: Type, event?: this["@eventTypes"][Type]): boolean

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

Since: ArcGIS Maps SDK for JavaScript 4.5

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters

Parameter	Type	Description	Required
type	`Type`	The name of the event.
event	`this["@eventTypes"][Type]`	The event payload.

Returns: boolean
true if a listener was notified

fetchAttributionData

inherited Method

Signature: fetchAttributionData (): Promise<any>

Inherited from: Layer

Fetches custom attribution data for the layer when it becomes available.

Returns: Promise<any>
Resolves to an object containing custom attribution data for the layer.

fetchTile

Method

Signature: fetchTile (level: number, row: number, col: number, options?: AbortOptions): Promise<HTMLImageElement | HTMLCanvasElement>

This method fetches a tile for the given level, row and column present in the view. Override this method if the data or image returned from the server needs to be processed before it can be displayed.

See also

Parameters

Parameter	Type	Description
level	`number`	Level of detail of the tile to fetch. This value is provided by LayerView.
row	`number`	The row (y) position of the tile fetch. This value is provided by LayerView.
col	`number`	The column (x) position of the tile to fetch. This value is provided by LayerView.
options	`AbortOptions`	Optional settings for the tile request. The options have the following properties.

Returns: Promise<HTMLImageElement | HTMLCanvasElement>
Returns a promise that resolves to an HTMLImageElement or HTMLCanvasElement.

Example

// Process the image returned from the server before
// it is displayed.
fetchTile: function (level, row, col, options) {
  // call getTileUrl method to construct the URL for
  // the image for the given level, row and col
  let url = this.getTileUrl(level, row, col);

  // request for the tile based on the generated url.
  // the signal option ensures that obsolete requests are aborted.
  return esriRequest(url, {
    responseType: "image",
    signal: options && options.signal
  })
  .then(function (response) {
    // get the image from the response
    let image = response.data;
    let width = this.tileInfo.size[0];
    let height = this.tileInfo.size[0];

    let canvas = document.createElement("canvas");
    canvas.width = width;
    canvas.height = height;
    let context = canvas.getContext("2d");

    // tint is a custom property of this layer
    // Apply the tint color provided by the application
    // to the canvas
    if (this.tint) {
      context.fillStyle = this.tint.toCss();
      context.fillRect(0, 0, width, height);

      // The pixels of the top layer are multiplied by the corresponding
      // pixel of the bottom layer. A darker picture is the result.
      context.globalCompositeOperation = "multiply";
    }
    context.drawImage(image, 0, 0, width, height);
    return canvas;
  }.bind(this));
}

getTileBounds

Method

Signature: getTileBounds (level: number, row: number, column: number, out?: [ number, number, number, number ]): [ number, number, number, number ]

Returns the bounds of the tile as an array of four numbers that be readily converted to an Extent object. The value for each item in the array is described in the following table:

Index	Value
0	Minimum x-value
1	Minimum y-value
2	Maximum x-value
3	Maximum y-value

Parameters

Parameter	Type	Description
level	`number`	The level of detail (LOD) of the tile.
row	`number`	The tile's row (y) position in the dataset.
column	`number`	The tiles column (x) position in the dataset.
out	`[ number, number, number, number ]`	Array for storing the tile bounds or extent.

Returns: [ number, number, number, number ]
Returns an array representing the tile bounds or extent.

getTileUrl

Method

Signature: getTileUrl (level: number, row: number, col: number): string | null | undefined

This method returns a URL to an image for a given level, row and column. Override this method to construct the URL for the image based on user interaction.

Parameters

Parameter	Type	Description
level	`number`	Level of detail. This value is provided by the LayerView.
row	`number`	Tile row. This value is provided by the LayerView.
col	`number`	Tile column. This value is provided by the LayerView.

Returns: string | null | undefined
Returns the URL to the tile image.

Example

// generate the tile url for a given level, row and column
getTileUrl: function (level, row, col) {
  // urlTemplate is a property of the custom layer.
  // value is provided by the application
  return this.urlTemplate.replace("{z}", level).replace("{x}", col).replace("{y}", row);
},

hasEventListener

inherited Method

Signature: hasEventListener <Type extends EventNames<this>>(type: Type): boolean

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

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

Parameters

Parameter	Type	Description	Required
type	`Type`	The name of the event.

Returns: boolean
Returns true if the class supports the input event.

isFulfilled

inherited Method

Signature: isFulfilled (): boolean

Inherited from: EsriPromiseMixin

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: boolean
Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected

inherited Method

Signature: isRejected (): boolean

Inherited from: EsriPromiseMixin

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns: boolean
Indicates whether creating an instance of the class has been rejected.

isResolved

inherited Method

Signature: isResolved (): boolean

Inherited from: EsriPromiseMixin

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns: boolean
Indicates whether creating an instance of the class has been resolved.

load

inherited Method

Signature: load (options?: AbortOptions | null | undefined): Promise<this>

Inherited from: LoadableMixin

Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.

This method must be called by the developer when accessing a resource that will not be loaded in a View.

The load() method only triggers the loading of the resource the first time it is called. The subsequent calls return the same promise.

It's possible to provide a signal to stop being interested into a Loadable instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad() can abort it.

Parameters

Parameter	Type	Description	Required
options	`AbortOptions \| null \| undefined`	Additional options.

Returns: Promise<this>
Resolves when the resources have loaded.

on

inherited Method

Signature: on <Type extends EventNames<this>>(type: Type, listener: EventedCallback<this["@eventTypes"][Type]>): ResourceHandle

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

Parameter	Type	Description	Required
type	`Type`	An event or an array of events to listen for.
listener	`EventedCallback<this["@eventTypes"][Type]>`	The function to call when the event fires.

Returns

ResourceHandle

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);
});

refresh

inherited Method

Signature: refresh (): void

Inherited from: RefreshableLayer

Since: ArcGIS Maps SDK for JavaScript 4.6

Fetches all the data for the layer.

See also

Returns: void

when

inherited Method

Signature: when <TResult1 = this, TResult2 = never>(onFulfilled?: OnFulfilledCallback<this, TResult1> | null | undefined, onRejected?: OnRejectedCallback<TResult2> | null | undefined): Promise<TResult1 | TResult2>

Type parameters: <TResult1 = this, TResult2 = never>

Inherited from: EsriPromiseMixin

Since: ArcGIS Maps SDK for JavaScript 4.6

when() may be leveraged once an instance of the class is created. This method takes two input parameters: an onFulfilled function and an onRejected function. The onFulfilled executes when the instance of the class loads. The onRejected executes if the instance of the class fails to load.

Parameters

Parameter	Type	Description	Required
onFulfilled	`OnFulfilledCallback<this, TResult1> \| null \| undefined`	The function to call when the promise resolves.
onRejected	`OnRejectedCallback \| null \| undefined`	The function to execute when the promise fails.

Returns: Promise<TResult1 | TResult2>
Returns a new promise for the result of onFulfilled that may be used to chain additional functions.

Example

// Although this example uses MapView, any class instance that is a promise may use when() in the same way
let view = new MapView();
view.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
});

Events

Name	Type
`layerview-create` inherited	CustomEvent<LayerLayerviewCreateEvent>
`layerview-create-error` inherited	CustomEvent<LayerLayerviewCreateErrorEvent>
`layerview-destroy` inherited	CustomEvent<LayerLayerviewDestroyEvent>
`refresh` inherited	CustomEvent<RefreshEvent>

layerview-create

inherited Event

layerview-create: CustomEvent<LayerLayerviewCreateEvent>

Inherited from: Layer

Fires after the layer's LayerView is created and rendered in a view.

See also

View.whenLayerView()

Example

// This function will fire each time a layer view is created for this
// particular view.
layer.on("layerview-create", function(event){
  // The LayerView for the layer that emitted this event
  event.layerView;
});

layerview-create-error

inherited Event

layerview-create-error: CustomEvent<LayerLayerviewCreateErrorEvent>

Inherited from: Layer

Fires when an error emits during the creation of a LayerView after a layer has been added to the map.

See also

View.whenLayerView()

Example

// This function fires when an error occurs during the creation of the layer's layerview
layer.on("layerview-create-error", function(event) {
  console.error("LayerView failed to create for layer with the id: ", layer.id, " in this view: ", event.view);
});

layerview-destroy

inherited Event

layerview-destroy: CustomEvent<LayerLayerviewDestroyEvent>

Inherited from: Layer

Fires after the layer's LayerView is destroyed and no longer renders in a view.

refresh

inherited Event

refresh: CustomEvent<RefreshEvent>

Inherited from: RefreshableLayer

Since: ArcGIS Maps SDK for JavaScript 4.21

Fires if the layer has the refreshInterval set or when refresh() method is called. The event payload indicates if the layer's data has changed.

See also

Examples

// listen to layer's refresh event to fetch the attachments
// for the updated features.
layer.on("refresh", async (event) =>{
  if (!event.dataChanged){
    return;
  }

  try {
    const query = layer.createQuery();
    const objectIds = await layer.queryObjectIds(query);
    let attachmentQuery = {
      objectIds: objectIds,
      definitionExpression: layer.definitionExpression,
      attachmentTypes: ["image/jpeg"]
    };

    const attachments = await layer.queryAttachments(attachmentQuery);

    attachmentQuery.objectIds.forEach(function (objectId) {
      if (attachments[objectId]) {
        // process the updated attachments
        let attachment = attachments[objectId];
        console.log("Attachments for objectId ", objectId, attachment);
      }
    });
  } catch (error) {
    console.log("attachment query error", error);
  }
});

// listen to layer's refresh event to fetch object ids of completed features
layer.on("refresh", function(event){
  if (event.dataChanged){
    const query = layer.createQuery();
    query.where = "Status = 'Completed'";
    layer.queryObjectIds(query).then((objectIds) => {
     // process returned features
    });
  }
});