ElementsController

---

The Elements controller allows you to get information about the elements on the map, and make changes to their visibility.

Extended by

• FeltController

Methods

getElement()

getElement(id: string): Promise<null | Element>

Get a single element from the map by its id.

Parameters

Parameter	Type	Description
id	string	The id of the element you want to get.

Returns

Promise<null | Element>

The requested element.

Example

const element = await felt.getElement("element-1");

---

getElementGeometry()

getElementGeometry(id: string): Promise<null | GeoJsonGeometry>

Get the geometry of an element in GeoJSON geometry format.

For most element types, the geometry returned is based on the coordinates property of the element, with some differences:

• For Circle elements, the geometry is a Polygon drawn from the center andradius properties.

• Path elements become MultiLineString geometries.

• Marker elements return a MultiLineString of the path traced by the user as they drew the marker. Note that this is not the polygon formed by filled-in "pen" stroke, which doesn't exactly follow the path traced by the user as it is smoothed and interpolated to create a continuous line.

• Text, Note and Image elements do not return geometry, so will return null.

Parameters

Parameter	Type	Description
id	string	The id of the element you want to get the geometry of.

Returns

Promise<null | GeoJsonGeometry>

Example

const geometry = await felt.getElementGeometry("element-1");
console.log(geometry?.type, geometry?.coordinates);

---

getElements()

getElements(constraint?: GetElementsConstraint): Promise<(null | Element)[]>

Gets elements from the map, according to the constraints supplied. If no constraints are supplied, all elements will be returned.

Parameters

Parameter	Type	Description
constraint?	GetElementsConstraint	The constraints to apply to the elements returned from the map.

Returns

Promise<(null | Element)[]>

All elements on the map.

Remarks

The elements in the map, ordered by the order specified in Felt. This is not necessarily the order that they are drawn in, as Felt draws points above lines and lines above polygons, for instance.

Example

const elements = await felt.getElements();

---

getElementGroup()

getElementGroup(id: string): Promise<null | ElementGroup>

Get an element group from the map by its id.

Parameters

Parameter	Type
id	string

Returns

Promise<null | ElementGroup>

The requested element group.

Example

const elementGroup = await felt.getElementGroup("element-group-1");

---

getElementGroups()

getElementGroups(constraint?: GetElementGroupsConstraint): Promise<(null | ElementGroup)[]>

Gets element groups from the map, according to the filters supplied. If no constraints are supplied, all element groups will be returned in rendering order.

Parameters

Parameter	Type	Description
constraint?	GetElementGroupsConstraint	The constraints to apply to the element groups returned from the map.

Returns

Promise<(null | ElementGroup)[]>

The requested element groups.

Example

const elementGroups = await felt.getElementGroups({ ids: ["element-group-1", "element-group-2"] });

---

setElementGroupVisibility()

setElementGroupVisibility(visibility: SetVisibilityRequest): Promise<void>

Hide or show element groups with the given ids.

Parameters

Parameter	Type
visibility	SetVisibilityRequest

Returns

Promise<void>

Example

felt.setElementGroupVisibility({ show: ["element-group-1", "element-group-2"], hide: ["element-group-3"] });

---

createElement()

createElement(element: ElementCreate): Promise<Element>

Create a new element on the map.

Parameters

Parameter	Type
element	ElementCreate

Returns

Promise<Element>

Example

const element = await felt.createElement({ type: "Place", coordinates: [10, 10] });

---

updateElement()

updateElement(element: ElementUpdate): Promise<Element>

Update an element on the map.

Parameters

Parameter	Type
element	ElementUpdate

Returns

Promise<Element>

Example

// Update a place element's coordinates
await felt.updateElement({
  id: "element-1",
  coordinates: [10, 20]
});

// Update a polygon's style
await felt.updateElement({
  id: "element-2",
  color: "#ABC123",
  fillOpacity: 0.5
});

---

deleteElement()

deleteElement(id: string): Promise<void>

Delete an element from the map.

Parameters

Parameter	Type
id	string

Returns

Promise<void>

Example

await felt.deleteElement("element-1");

Events

onElementCreate()

onElementCreate(args: { handler: (change: ElementChangeCallbackParams) => void; }): VoidFunction

Adds a listener for when an element is created.

Parameters

Parameter	Type	Description
args	{ handler: (change: ElementChangeCallbackParams) => void; }	-
args.handler	(change: ElementChangeCallbackParams) => void	The handler that is called when an element is created. This will fire when elements are created programatically, or when the user starts creating an element with a drawing tool. When the user creates an element with a drawing tool, it can begin in an invalid state, such as if you've just placed a single point in a polygon. You can use the isBeingCreated property to determine if the element is still being created by a drawing tool. If you want to know when the element is finished being created, you can use the `onElementCreateEnd` listener.

Returns

VoidFunction

A function to unsubscribe from the listener

Example

const unsubscribe = felt.onElementCreate({
  handler: (element) => console.log(element.id),
});

// later on...
unsubscribe();

---

onElementCreateEnd()

onElementCreateEnd(args: { handler: (params: { element: Element; }) => void; }): VoidFunction

Listens for when a new element is finished being created by a drawing tool.

This differs from the `onElementCreate` listener, which fires whenever an element is first created. This fires when the user finishes creating an element which could be after a series of interactions.

For example, when creating a polygon, the user places a series of points then finishes by pressing Enter or Escape. Or when creating a Place element, they add the marker, type a label, then finally deselect the element.

Parameters

Parameter	Type	Description
args	{ handler: (params: { element: Element; }) => void; }	-
args.handler	(params: { element: Element; }) => void	The handler to call whenever this event fires.

Returns

VoidFunction

A function to unsubscribe from the listener

Example

const unsubscribe = felt.onToolCreatedElement({
  handler: (params) => console.log(params),
});

// later on...
unsubscribe();

---

onElementChange()

onElementChange(args: { options: { id: string; }; handler: (change: ElementChangeCallbackParams) => void; }): VoidFunction

Adds a listener for when an element changes.

This will fire when an element is being edited, either on the map by the user or programatically.

Like the `onElementCreate` listener, this will fire when an element is still being created by a drawing tool.

You can check the `isBeingCreated` property to determine if the element is still being created by a drawing tool.

Parameters

Parameter	Type	Description
args	{ options: { id: string; }; handler: (change: ElementChangeCallbackParams) => void; }	-
args.options	{ id: string; }	-
args.options.id	string	The id of the element to listen for changes to.
args.handler	(change: ElementChangeCallbackParams) => void	The handler that is called when the element changes.

Returns

VoidFunction

A function to unsubscribe from the listener

Example

const unsubscribe = felt.onElementChange({
  options: { id: "element-1" },
  handler: ({element}) => console.log(element.id),
});

// later on...
unsubscribe();

---

onElementDelete()

onElementDelete(args: { options: { id: string; }; handler: () => void; }): VoidFunction

Adds a listener for when an element is deleted.

Parameters

Parameter	Type	Description
args	{ options: { id: string; }; handler: () => void; }	-
args.options	{ id: string; }	-
args.options.id	string	The id of the element to listen for deletions of.
args.handler	() => void	The handler that is called when the element is deleted.

Returns

VoidFunction

A function to unsubscribe from the listener

Example

const unsubscribe = felt.onElementDelete({
  options: { id: "element-1" },
  handler: () => console.log("element-1 deleted"),
});

// later on...
unsubscribe();

---

onElementGroupChange()

onElementGroupChange(args: { options: { id: string; }; handler: (change: ElementGroupChangeCallbackParams) => void; }): VoidFunction

Adds a listener for when an element group changes.

Parameters

Parameter	Type
args	{ options: { id: string; }; handler: (change: ElementGroupChangeCallbackParams) => void; }
args.options	{ id: string; }
args.options.id	string
args.handler	(change: ElementGroupChangeCallbackParams) => void

Returns

VoidFunction

A function to unsubscribe from the listener

Example

const unsubscribe = felt.onElementGroupChange({
  options: { id: "element-group-1" },
  handler: elementGroup => console.log(elementGroup.id),
});

// later on...
unsubscribe();