LayerStructure class

The LayerStructure class reflects the structure of the operational layers in the current map. It is used to traverse and operate each layer and sublayer abstracted as a LayerNode in the LayerStructure.

AMD Module Require

require(["jimu/LayerStructure"], function(LayerStructure) { /* code goes here */ });

Constructor

There is a single instance of LayerStructure in the Web AppBuilder environment. var layerStructureInstance = LayerStructure.getInstance(); Example: Prints the tree structure of the operational layers in the current map in the console window. `var layerStructure = LayerStructure.getInstance(); function printLayerTree() { layerStructure.traversal(function(layerNode) { var indent = ""; for(var i = 0; i < layerNode.getNodeLevel(); i++) {indent += " ";} console.log(indent, layerNode.title); }); } printLayerTree(); layerStructure.on(LayerStructure.EVENT_STRUCTURE_CHANGE, function(eventObject) { // reprint the layer tree if the layer structure has been changed; printLayerTree(); });`

There is a single instance of LayerStructure in the Web AppBuilder environment.

var layerStructureInstance = LayerStructure.getInstance();

Example:

Prints the tree structure of the operational layers in the current map in the console window.

var layerStructure = LayerStructure.getInstance();
        function printLayerTree() {
          layerStructure.traversal(function(layerNode) {
            var indent = "";
            for(var i = 0; i < layerNode.getNodeLevel(); i++) {indent += "  ";}
            console.log(indent, layerNode.title);
          });
        }

        printLayerTree();

        layerStructure.on(LayerStructure.EVENT_STRUCTURE_CHANGE, function(eventObject) {
          // reprint the layer tree if the layer structure has been changed;
          printLayerTree();
        });

Constants


STRUCTURE_CHANGE_ADD	Type of structure change event when layerNodes are added.
STRUCTURE_CHANGE_REMOVE	Type of structure change event when layerNodes are removed.
STRUCTURE_CHANGE_SUBNODE_ADD	Type of structure change event when subLayerNodes are added.
STRUCTURE_CHANGE_SUBNODE_REMOVE	Type of structure change event when subLayerNodes are removed.
STRUCTURE_CHANGE_NODE_UPDATE	Type of structure change event when layerNodes are updated.
STRUCTURE_CHANGE_REORDER	Type of structure change event when layerNodes are reordered.
EVENT_STRUCTURE_CHANGE	Event name for a structure change.
EVENT_TOGGLE_CHANGE	Event name for a toggle change.
EVENT_VISIBILITY_CHANGE	Event name for a visibility change.
EVENT_FILTER_CHANGE	Event name for a filter change.
EVENT_RENDERER_CHANGE	Event name for a renderer change.
EVENT_OPACITY_CHANGE	Event name for an opacity change.

Methods

addTable(table) Adds a table to layerStructure. Parameters: `table = { id: Optional parameters, title: title of new table, url: alternative with featureCollectionData, featureCollectionData: alternative with url, options: Optional parameters. See options list of FeatureLayer Constructor from ArcGIS JavaScript API reference. }` Return value: LayerNode

addTable(table)

Adds a table to layerStructure.

Parameters:

  table = {
      id: Optional parameters,
      title: title of new table,
      url: alternative with featureCollectionData,
      featureCollectionData: alternative with url,
      options: Optional parameters. See options list of FeatureLayer Constructor from
               ArcGIS JavaScript API reference.
  }

Return value: LayerNode


getBasemapLayerObjects() Gets the layerObjects from the basemap. Parameters: null Return value: LayerObject[]


getLayerNodes() Gets the operational layerNodes in the current map. Parameters: null Return value: LayerNode[]


getNodeById(nodeId) Gets the layerNode or tableNode by ID. Parameters: nodeId—layerNode or tableNode Id. Return value: LayerNode


getTableNodes() Gets the operational tableNodes in the current map. Parameters: null Return value: LayerNode[]


getWebmapLayerNodes() Gets the operational layerNodes that are defined in the web map. Parameters: null Return value: LayerNode[]


getWebmapTableNodes() Gets the operational tableNodes that are defined in the web map. Parameters: null Return value: LayerNode[]


removeTable(nodeId) Removes a tableNode from layerStructure by the node ID. Parameters: nodeId—The tableNode ID. Return value: null


traversal: function(callback) Traverses all nodes of the layerStructure with Depth-First-Search. Parameters: callback: function(layerNode) {}; Callback parameters: layerNode Callback return value: Boolean—Returns true when the traversal is interrupted; returns false when the traversal continues. Return value: Boolean—Returns true when the traversal is interrupted; returns false when the traversal is complete.


traversalWithNodes: function(callback, nodes) Traverses all nodes of nodes parameter with Depth-First-Search. Parameters: callback: function(layerNode) {}; Callback parameters: layerNode Callback return value: Boolean— Returns true when the traversal is interrupted; returns false when the traversal continues. nodes—The layerNodes array Return value: Boolean—Returns true when the traversal is interrupted; returns false when the traversal is complete.

Events


structure-change Fires when the structure is changed. Event object: `{ type: String layerNodes: LayerNode[] rootLayerNodes: LayerNode[] }` See also: EVENT_STRUCTURE_CHANGE in the Constants table.


toggle-change Fires when the layerNodes toggle is changed. Event object: `{ layerNodes: LayerNode[] }` See also: EVENT_TOGGLE_CHANGE in the Constants table


visibility-change Fires when the visibility of layerNodes is changed. Event object: `{ layerNodes: LayerNode[] }` See also: EVENT_TOGGLE_CHANGE in the Constants table.


filter-change Fires when the layerNodes filter is changed. Event object: `{ layerNodes: LayerNode[] }` See also: EVENT_FILTER_CHANGE in the Constants table.


renderer-change Fires when the layerNodes renderer is changed. Event object: `{ layerNodes: LayerNode[] }` See also: EVENT_RENDERER_CHANGE in the Constants table.


opacity-change Fires when the layerNodes opacity is changed. Event object: `{ layerNodes: LayerNode[] }` See also: EVENT_OPACITY_CHANGE in the Constants table.