FeatureLayer

A layer that can visualize feature data. Feature layers can display Feature data from a range of online feature table sources, such as ServiceFeatureTable, WfsFeatureTable or OgcFeatureCollectionTable source, and offline sources such as GeodatabaseFeatureTable, ShapefileFeatureTable, or GeoPackageFeatureTable. You can construct a feature layer object using these feature table sources or you can obtain it directly from a map or scene's collection of GeoModel.operationalLayers.

Feature layers can also be used to store features associated with a utility network. To display features in a FeatureCollectionTable, use FeatureCollectionLayer instead.

Feature layers can be used to display, select, and query features in a layer. Individual features can be queried and filtered based on spatial queries or SQL queries. String comparisons for features queried in service feature tables are case insensitive.

If the underlying feature service or table supports editing, you can use it with a feature layer as a basis for editing geometry, attributes, and attachments.

The features in a feature layer are retrieved as needed by the app. Features can be downloaded from a sync-enabled feature service when the device is connected and cached locally for use when the device is offline. Edits can then be synchronized back to the service.

Functional characteristics

The following sources can be rendered using a feature layer:

  • Feature service - backed by a ServiceFeatureTable. The feature data from the service is cached locally in the table. New features are retrieved automatically when you navigate the map. The local table cache is discarded when the layer is disposed. If sync is enabled, features can be created, edited, and synchronized back to the server.

  • Geodatabase - backed by a GeodatabaseFeatureTable. The geodatabase can be a replica of a feature service, which allows synchronizing with the feature service, or taking the content of a feature service offline. Use GeodatabaseSyncTask to synchronize the geodatabase with the service. The geodatabase can also be a mobile geodatabase created by ArcGIS Pro. These geodatabases cannot be synced and use a default renderer.

  • Shapefile - backed by a ShapefileFeatureTable. Use a feature layer to show the contents of a shapefile (.shp).

  • Geopackage - backed by a GeoPackageFeatureTable. This uses a feature layer to render the tables in a GeoPackage (.gpkg). A GeoPackage is a data source that conforms to the https://www.ogc.org/standards/geopackage. Geopackage feature tables can be edited and saved, but do not support sync, because there is no backing feature service. This API supports GeoPackage versions 1.0, 1.1, and 1.2.

  • Web Feature Service (WFS) - backed by a WfsFeatureTable. You can populate the table using QueryParameters or raw XML-encoded GetFeature queries. A WFS feature table only supports the manual cache feature request mode. This API supports OGC WFS[https://www.ogc.org/standards/wfs] versions 2.0.0 and 2.0.2. WFS server implementations are inconsistent in how they expect coordinates to be formatted. Some return and expect coordinates in (x,y) order, while others expect (y,x). This API anticipates the order but you can configure it with the WfsFeatureTable.axisOrder and WfsFeatureTable.filterAxisOrder.

  • OGC API Features - Backed by an OgcFeatureCollectionTable. You can populate the table using QueryParameters. An OCG feature collection table only supports the manual cache feature request mode. This API supports OGC API - Features - Part 1[https://docs.opengeospatial.org/is/17-069r3/17-069r3.html] and https://docs.opengeospatial.org/is/18-058/18-058.html.

The features displayed in a FeatureLayer are automatically projected to match the map or scene's GeoModel.spatialReference, if necessary. Local tables cannot be projected automatically.

FeatureLayer does not expose every value defined in the web map or web scene specification. You can obtain a dictionary of unsupported values from FeatureLayer.unsupportedJson. The FeatureLayer also provides FeatureLayer.unknownJson to return JSON that is not recognized in the web map or web scene specification.

Performance characteristics

The feature layer offers excellent display performance when zooming and panning the map within the extent of locally cached features. This is because features are drawn natively and full feature information is cached locally in a geodatabase, shapefile, or GeoPackage. Querying features is also efficient, enabling app functions such as real-time updates of query results in a map.

Initially, a local cache must be created. The initial download to the device may require extensive network usage and subsequent local device storage. App memory usage increases with the number and complexity of the features cached. You can eliminate the network usage by provisioning the cache directly to the device in advance.

If the feature layer's FeatureTable is backed by a service it has three feature request modes (FeatureRequestMode) that control how and when features are requested from the service:

  • On interaction cache - Features are requested automatically for the visible map or scene extent. As the user pans and zooms, features are cached locally. If the user returns to an area where features have already been loaded, the table won't need to download those features again.

  • Manual cache - Features are manually populated using a call to ServiceFeatureTable.populateFromService(QueryParameters, Boolean, MutableListImpl). Once populated, all queries are made against the local table only. ServiceFeatureTable.populateFromService(QueryParameters, Boolean, MutableListImpl) can be called again to retrieve more features from the service.

  • On interaction, no cache - Features are requested automatically for the visible map extent. As the user pans and zooms, features outside the visible extent are not cached and must be downloaded again each time.

Since

200.1.0

See also

Inheritors

Types

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object Companion

Properties

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A SQL expression which limits the features available for query and display on the feature layer. The definition expression string should follow standard SQL syntax as detailed in the SQL reference for query expressions used in ArcGIS[https://pro.arcgis.com/en/pro-app/latest/help/mapping/navigation/sql-reference-for-elements-used-in-query-expressions.htm] document.

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Defines how features are filtered from the display. Use this property to reduce the number of features displayed in the map or scene view. The filter aims to improve data visualization and optimize rendering performance. It only affects the display of features so all features are still available for query methods such as FeatureLayer.selectFeatures(QueryParameters, SelectionMode): Future.

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Defines properties for dynamically aggregating and summarizing groups of features as the map scale changes. FeatureReduction is only supported for point feature layers in dynamic rendering mode (FeatureRenderingMode.Dynamic) in 2D. The following conditions will generate a LayerViewState error and will result in the layer rendering the original features.

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The feature table whose features are drawn on the map by this layer.

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The collection of LabelDefinition objects that define how labels are displayed.

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True if features in the layer are labelled, otherwise false.

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The renderer specifies how the features are symbolized.

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The mode defines how the feature layer is rendered. FeatureRenderingMode.Static mode is better suited for displaying large datasets (in terms of the number of vertices) and for complex symbology because it does not update the layer's display while pan/zoom operations are in progress.

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True if the layer's symbols and labels honor the map's reference scale, otherwise false. If the map has a positive reference scale, and the layer honors it, then symbols and labels are drawn at their specified size when the viewing scale is the same as the reference scale. They will grow or shrink as the view zooms in or out, to keep the symbol a fixed size on the map. If the map has no reference scale, the reference scale is zero, or this feature layer's scaleSymbols property is false, then the symbols and labels will be drawn at their fixed screen size.

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Properties that are applied when the layer is rendered in a 3D scene using a SceneView object.

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The mode defines whether feature tiling is used to retrieve the features from the feature service. The default tiling mode is FeatureTilingMode.EnabledWhenSupported.

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Unknown data from the source JSON. Unknown JSON is a dictionary of values not defined in the ArcGIS specification used to create this object but found in the source JSON. If the object is written back to JSON, any unknown JSON data is not persisted. The ArcGIS specification may be for a web map, web scene, REST API, and so on.

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Unsupported data from the source JSON. Unsupported JSON is a dictionary of values defined in the ArcGIS specification used to create this object but not currently used in this API. If the object is written back to JSON, any unsupported JSON data is persisted. The ArcGIS specification may be from a web map, web scene, REST API, and so on.

Inherited properties

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The attribution text for the layer.

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open override val canChangeVisibility: Boolean

A flag indicating whether the layer content's visibility can be changed. A flag indicating whether the layer content visibility can be changed. Will return false if an error occurs.

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The description for the layer.

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Defines the properties that allow a layer to be floor-aware. When a layer is configured as floor-aware, it has a FloorAware.floorDefinition property that defines properties that allow a layer to be floor-aware. When it is null (default value) the specific layer does not support floor filtering.

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The full extent of this layer, which is the extent where all layer data is contained. You can use this to zoom to all of the data contained in this layer. For feature layers, the extent is retrieved from its FeatureTable.extent.

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open override val fullTimeExtent: StateFlow<TimeExtent?>

The full time extent of the layer. If the layer, such as an ArcGISMapImageLayer, has sublayers with different time extents, fullTimeExtent is a union of its sublayer's time extents.

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var id: String

The unique identifying string for the layer, as specified in a map or scene. The id is used by other parts of this API to refer to a specific Layer, such as in a set of FeatureFenceParameters or a FacilityLayerDefinition. If not supplied, all layers will be assigned a unique id when created.

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True if the layer supports identify, false otherwise. The value of this property may not be correct until the layer is in a fully loaded state.

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open override var isPopupEnabled: Boolean

A flag indicating whether the PopupDefinition defined on the PopupSource is enable / disable. Will return false if an error occurs.

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open override var isTimeFilteringEnabled: Boolean

True if the layer filters data based on its GeoView.timeExtent, false otherwise. This is only applicable if the layer's TimeAware.supportsTimeFiltering value is true. If the GeoView.timeExtent value is null, no time filtering is applied and all content is rendered.

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open override var isVisible: Boolean

The layer content's visibility. The layer content visibility. Will return false if an error occurs.

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val item: Item?

The item the layer has been created from.

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open override val loadStatus: StateFlow<LoadStatus>

The load status.

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The maximum scale for the layer. The maximum scale at which this layer is visible. If the map or scene is zoomed in beyond this scale, the layer will not be visible. A value of 0 means there is no maximum scale threshold and the layer will be visible at the smallest scale available for the map or scene. If the value is nil, there is no maximum scale. All of the connected map and scene views will be updated.

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The minimum scale for the layer. The minimum scale at which this layer is visible. If the map or scene is zoomed out beyond this scale, the layer will not be visible. A value of 0 means there is no minimum scale threshold and the layer will be visible at the largest scale available for the map or scene. If the value is nil, there is no minimum scale. All of the connected map and scene views will be updated.

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open override var name: String

The name of this layer.

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The opacity for the layer. The opacity of this layer as a value between 0 (fully transparent) and 1 (fully opaque). The default opacity value is 1.

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open override var popupDefinition: PopupDefinition?

The pop-up definition. The PopupDefinition associated with the popup source. A null if an error occurs or if the popup source is not associated with a pop-up definition.

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open override var refreshInterval: Long?

The objects refresh interval. The refresh interval, in milliseconds. A refresh interval of null means never refresh.

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open override var showInLegend: Boolean

A flag indicating whether the layer content participates in the legend. A flag indicating whether the layer content is shown in the legend.

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The spatial reference of the layer.

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open override val subLayerContents: StateFlow<List<LayerContent>>

The sub layer contents of a layer content.

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open override val supportsTimeFiltering: Boolean

True if the layer supports filtering data based on its time values, false otherwise.

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open override val timeInterval: TimeValue?

The suggested time slider step size for this time aware layer. You can use this information to set the step size for a time slider control. The value is null if no time interval is suggested. The author of the layer's data typically configures this property if the data has been collected on a regular basis. For example, the daily position of a hurricane.

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open override var timeOffset: TimeValue?

The amount of time by which the temporal values of this layer's data points are offset when displaying it in a GeoView. The time offset is subtracted from the time extent set on the layer's GeoView. This is useful if you want to overlay data in multiple layers that lies within different temporal extents. For example, if you want to compare data in one layer for a certain year with data in the same layer from the subsequent year, you can create two layers that reference the same data's service endpoint but set the TimeValue in one of the layers to be one year.

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val visibilityChanged: SharedFlow<Boolean>

Callback invoked when the visibility of the layer changes.

Functions

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Clears all selected features.

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open override fun clone(): FeatureLayer

Clones the FeatureLayer.

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Returns a collection of the currently selected features.

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Reset the visibility of all features back to their original state.

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Reset the renderer back to the original renderer provided by the FeatureTable.

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fun selectFeature(feature: Feature)

Selects the given feature and adds it to the current collection of selected features. Selected features are rendered according to the GeoView.selectionProperties.

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Selects the given features and adds them to the current collection of selected features. Use the FeatureLayer.getSelectedFeatures(): Future to retrieve all of the selected features.

Selects the features that match the criteria in the QueryParameters object and adds them to the current collection of selected features.

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fun setFeaturesVisible(features: Iterable<Feature>, visible: Boolean)

Sets the visibility of the given features.

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fun setFeatureVisible(feature: Feature, visible: Boolean)

Sets the visibility of the given feature.

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fun unselectFeature(feature: Feature)

Unselects the given feature and removes it from the current collection of selected features.

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Unselects the given features and removes them from the current collection of selected features.

Inherited functions

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open override fun cancelLoad()

Cancels loading metadata for the Loadable object.

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open operator override fun equals(other: Any?): Boolean
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open suspend override fun fetchLegendInfos(): Result<List<LegendInfo>>

Fetches the list of legend info.

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open override fun hashCode(): Int
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open override fun isVisibleAtScale(scale: Double): Boolean

Returns the layer content's effective visibility at the specified scale. Returns the effective layer content visibility. This effective visibility takes care of the effective visibility of the parents at the specified scale. Will return false if an error occurs.

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open suspend override fun load(): Result<Unit>

Loads the metadata for the object.

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open suspend override fun retryLoad(): Result<Unit>

Loads or retries loading metadata for the object.