ESM: import BaseTileLayer from "@arcgis/core/layers/BaseTileLayer.js";
CDN: const BaseTileLayer = await $arcgis.import("@arcgis/core/layers/BaseTileLayer.js");
Class: @arcgis/core/layers/BaseTileLayer
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 createSubclass() on the BaseTileLayer class. You may create a custom tile layer for one of the following reasons:
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,
}
});
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);
}
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.
Show inherited properties Hide inherited properties
Property Details blendMode String
Since: ArcGIS Maps SDK for JavaScript 4.16 BaseTileLayer since 4.4, blendMode added at 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.
The following factors will affect the blend result:
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.
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.
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.
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.
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).
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 terrain basemap into a dark themed basemap in no time.
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.
Possible Values:"average" |"color-burn" |"color-dodge" |"color" |"darken" |"destination-atop" |"destination-in" |"destination-out" |"destination-over" |"difference" |"exclusion" |"hard-light" |"hue" |"invert" |"lighten" |"lighter" |"luminosity" |"minus" |"multiply" |"normal" |"overlay" |"plus" |"reflect" |"saturation" |"screen" |"soft-light" |"source-atop" |"source-in" |"source-out" |"vivid-light" |"xor"
Inherited
Property declaredClass Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.
The name of the class. The declared class name is formatted as esri.folder.className.
Since: ArcGIS Maps SDK for JavaScript 4.18 BaseTileLayer since 4.4, effect added at 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
featureEffect, effect, opacity and blendMode.Known Limitations
cluster enabled.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)"
}
];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.
Example
// Once the layer loads, set the view's extent to the layer's fullextent
layer.when(function(){
view.extent = layer.fullExtent;
});Inherited
Property id String
The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.
Inherited
Property listMode String
Indicates how the layer should display in the LayerList widget. The possible values are listed below.
Possible Values:"show" |"hide" |"hide-children"
The Error object returned if an error occurred while loading.
Inherited
Property loadStatus Stringreadonly
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.Possible Values:"not-loaded" |"loading" |"failed" |"loaded"
Default Value:"not-loaded"
Inherited
Property loadWarnings Object[]readonly
A list of warnings which occurred while loading.
Inherited
Property loaded Booleanreadonly
Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.
maxScale Number
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.
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 Number
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.
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;Inherited
Property opacity Number
The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.
Example
// Makes the layer 50% transparent
layer.opacity = 0.5;Since: ArcGIS Maps SDK for JavaScript 4.27 Layer since 4.0, parent added at 4.27.
The parent to which the layer belongs.
Inherited
Property persistenceEnabled Booleanreadonly
Since: ArcGIS Maps SDK for JavaScript 4.28 Layer since 4.0, persistenceEnabled added at 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.
refreshInterval Number
Since: ArcGIS Maps SDK for JavaScript 4.6 BaseTileLayer since 4.4, refreshInterval added at 4.6.
Refresh interval of the layer in minutes. Value of 0 indicates no refresh.
Example
// the layer will be refreshed every minute.
layer.refreshInterval = 1;The spatial reference of the layer.
The tiling scheme information for the layer.
The title of the layer used to identify it in places such as the LayerList widget.
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 Stringreadonly
For BaseTileLayer the type is base-tile.
Possible Values:"base-tile" |"bing-maps"
Inherited
Property uid Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.33 Layer since 4.0, uid added at 4.33.
An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.
Since: ArcGIS Maps SDK for JavaScript 4.30 Layer since 4.0, visibilityTimeExtent added at 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 start or 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.
Inherited
Property visible Boolean
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.
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;
}
}
);Show inherited methods Hide inherited methods
Method DetailsInherited
Method addHandles(handleOrHandles, groupKey)
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 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
Handles marked for removal once the object is destroyed.
groupKey *
optionalKey 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.
addResolvingPromise(promiseToLoad)
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.
Parameter
promiseToLoad Promise
A promise that must resolve for the layer to resolve and move from the loading status to being loaded.
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);
}
});Inherited
Method cancelLoad()
Cancels a load() operation if it is already in progress.
Inherited
Method createLayerView(view, options){Promise<LayerView>}
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.
Parameters
view *
The parent view.
optionalAn object specifying additional options. See the object specification table below for the required properties of this object.
Returns
Inherited
Method destroy()
Since: ArcGIS Maps SDK for JavaScript 4.17 Layer since 4.0, destroy added at 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.
Inherited
Method emit(type, event){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.5 Layer since 4.0, emit added at 4.5.
Emits an event on the instance. This method should only be used when creating subclasses of this class.
Parameters
The name of the event.
optionalThe event payload.
Returns
Type Description Booleantrue if a listener was notified
Inherited
Method fetchAttributionData(){Promise<Object>}
Fetches custom attribution data for the layer when it becomes available.
Returns
Type Description Promise<Object> Resolves to an object containing custom attribution data for the layer.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.
Parameters
Level of detail of the tile to fetch. This value is provided by LayerView.
The row (y) position of the tile fetch. This value is provided by LayerView.
The column (x) position of the tile to fetch. This value is provided by LayerView.
optionalOptional settings for the tile request. The options have the following properties.
Specification
optionalAn AbortSignal to abort the request. When overriding fetchTile, signal should be handled, for example by passing it on to request or by aborting pending operations. An aborted call to fetchTile should reject its returned promise with an instance of Error.
Returns
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(level, row, column, out){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-valueParameters
The level of detail (LOD) of the tile.
The tile's row (y) position in the dataset.
The tiles column (x) position in the dataset.
optionalArray for storing the tile bounds or extent.
Returns
Type Description Number[] Returns an array representing the tile bounds or extent.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.
Returns
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);
},Inherited
Method hasEventListener(type){Boolean}
Indicates whether there is an event listener on the instance that matches the provided event name.
Returns
Type Description Boolean Returns true if the class supports the input event.Inherited
Method hasHandles(groupKey){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 4.25.
Returns true if a named group of handles exist.
Parameter
groupKey *
optionalA group key.
Returns
Type Description Boolean Returnstrue 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");
}Inherited
Method isFulfilled(){Boolean}
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).Inherited
Method isRejected(){Boolean}
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.Inherited
Method isResolved(){Boolean}
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.Inherited
Method load(options){Promise}
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
optionalAdditional options.
Specification
optionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.
Returns
Type Description Promise Resolves when the resources have loaded.Inherited
Method on(type, listener){Object}
Registers an event handler on the instance. Call this method to hook an event with a listener.
Returns
Type Description Object Returns an event handler with aremove() 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);
});Since: ArcGIS Maps SDK for JavaScript 4.6 BaseTileLayer since 4.4, refresh added at 4.6.
Fetches all the data for the layer.
Inherited
Method removeHandles(groupKey)
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 4.25.
Removes a group of handles owned by the object.
Parameter
groupKey *
optionalA 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");Inherited
Method when(callback, errback){Promise}
Since: ArcGIS Maps SDK for JavaScript 4.6 Layer since 4.0, when added at 4.6.
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
optionalThe function to call when the promise resolves.
optionalThe function to execute when the promise fails.
Returns
Type Description Promise Returns a new promise for the result ofcallback 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
});Show inherited events Hide inherited events
Event DetailsInherited
Event layerview-create
Fires after the layer's LayerView is created and rendered in a view.
The view in which the layerView was created.
The LayerView rendered in the view representing the layer in layer.
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;
});Inherited
Event layerview-create-error
Fires when an error emits during the creation of a LayerView after a layer has been added to the map.
The view that failed to create a layerview for the layer emitting this event.
An error object describing why the layer view failed to create.
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);
});Inherited
Event layerview-destroy
Fires after the layer's LayerView is destroyed and no longer renders in a view.
The view in which the layerView was destroyed.
The destroyed LayerView representing the layer.
Since: ArcGIS Maps SDK for JavaScript 4.21 BaseTileLayer since 4.4, refresh added at 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.
Example
// listen to layer's refresh event to fetch the attachments
// for the updated features.
layer.on("refresh", function(event){
if (event.dataChanged){
const query = layer.createQuery();
layer.queryObjectIds(query).then(function (objectIds) {
let attachmentQuery = {
objectIds: objectIds,
definitionExpression: layer.definitionExpression,
attachmentTypes: ["image/jpeg"]
};
layer.queryAttachments(attachmentQuery).then(function (attachments) {
attachmentQuery.objectIds.forEach(function (objectId) {
if (attachments[objectId]) {
// process the updated attachments
let attachment = attachments[objectId];
}
});
})
.catch(function (error) {
console.log("attachment query error", error);
});
});
}
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