# Class: Circle

This documentation is for OpenLayers v10.9.0. The latest is v.

## ol/geom/Circle~Circle

    import Circle from 'ol/geom/Circle.js';

Circle geometry.

#### new Circle(center, radius, layout)

geom/Circle.js, line 15

  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | Center. For internal use, flat coordinates in combination with `layout` and no `radius` are also accepted.
  `radius` | number | undefined | Radius in units of the projection.
  `layout` | GeometryLayout | undefined | Layout.

  ##### Fires:

  - `change` (BaseEvent) - Generic change event. Triggered when the revision counter is increased.
  - `error` (BaseEvent) - Generic error event. Triggered when an error occurs.
  - `propertychange` (ObjectEvent) - Triggered when a property is changed.

### Extends

- SimpleGeometry

### Methods

#### applyTransform(transformFn) inherited

geom/SimpleGeometry.js, line 208

  Apply a transform function to the coordinates of the geometry. The geometry is modified in place. If you do not want the geometry modified in place, first `clone()` it and then use this function on the clone.

  Name | Type | Description
  --- | --- | ---
  `transformFn` | TransformFunction | Transform function. Called with a flat array of geometry coordinates.

#### changed() inherited

Observable.js, line 68

  Increases the revision counter and dispatches a 'change' event.

#### clone(){Circle}

geom/Circle.js, line 39

  Make a complete copy of the geometry.

  ##### Returns:

  Clone.

#### dispatchEvent(event){boolean | undefined} inherited

events/Target.js, line 85

  Dispatches an event and calls all listeners listening for events of this type. The event parameter can either be a string or an Object with a `type` property.

  Name | Type | Description
  --- | --- | ---
  `event` | BaseEvent | string | Event object.

  ##### Returns:

  `false` if anyone called preventDefault on the event object or if any of the listeners returned false.

#### get(key){*} inherited

Object.js, line 136

  Gets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.

  ##### Returns:

  Value.

#### getCenter(){Coordinate}

geom/Circle.js, line 99

  Return the center of the circle as `coordinate`.

  ##### Returns:

  Center.

#### getClosestPoint(point, closestPoint){Coordinate} inherited

geom/Geometry.js, line 154

  Return the closest point of the geometry to the passed point as `coordinate`.

  Name | Type | Description
  --- | --- | ---
  `point` | Coordinate | Point.
  `closestPoint` | Coordinate | undefined | Closest point.

  ##### Returns:

  Closest point.

#### getExtent(extent){Extent} inherited

geom/Geometry.js, line 187

  Get the extent of the geometry.

  Name | Type | Description
  --- | --- | ---
  `extent` | Extent | undefined | Extent.

  ##### Returns:

  extent Extent.

#### getFirstCoordinate(){Coordinate} inherited

geom/SimpleGeometry.js, line 69

  Return the first coordinate of the geometry.

  ##### Returns:

  First coordinate.

#### getKeys(){Array.<string>} inherited

Object.js, line 149

  Get a list of object property names.

  ##### Returns:

  List of property names.

#### getLastCoordinate(){Coordinate} inherited

geom/SimpleGeometry.js, line 85

  Return the last coordinate of the geometry.

  ##### Returns:

  Last point.

#### getLayout(){GeometryLayout} inherited

geom/SimpleGeometry.js, line 96

  Return the `layout` of the geometry.

  ##### Returns:

  Layout.

#### getProperties(){NoInfer.<Properties>} inherited

Object.js, line 158

  Get an object of all property names and values.

  ##### Returns:

  Object.

#### getRadius(){number}

geom/Circle.js, line 126

  Return the radius of the circle.

  ##### Returns:

  Radius.

#### getRevision(){number} inherited

Observable.js, line 79

  Get the version number for this object. Each time the object is modified, its version number will be incremented.

  ##### Returns:

  Revision.

#### getType(){Type}

geom/Circle.js, line 146

  Get the type of this geometry.

  ##### Returns:

  Geometry type.

#### intersectsCoordinate(coordinate){boolean} inherited

geom/Geometry.js, line 167

  Returns true if this geometry includes the specified coordinate. If the coordinate is on the boundary of the geometry, returns false.

  Name | Type | Description
  --- | --- | ---
  `coordinate` | Coordinate | Coordinate.

  ##### Returns:

  Contains coordinate.

#### intersectsExtent(extent){boolean}

geom/Circle.js, line 157

  Test if the geometry and the passed extent intersect.

  Name | Type | Description
  --- | --- | ---
  `extent` | Extent | Extent.

  ##### Returns:

  `true` if the geometry and the extent intersect.

#### on(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 152

  Listen for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### once(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 164

  Listen once for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### rotate(angle, anchor)

geom/Circle.js, line 245

  Rotate the geometry around a given coordinate. This modifies the geometry coordinates in place.

  Name | Type | Description
  --- | --- | ---
  `angle` | number | Rotation angle in counter-clockwise radians.
  `anchor` | Coordinate | The rotation center.

#### scale(sx, sy, anchor) inherited

geom/SimpleGeometry.js, line 255

  Scale the geometry (with an optional origin). This modifies the geometry coordinates in place.

  Name | Type | Description
  --- | --- | ---
  `sx` | number | The scaling factor in the x-direction.
  `sy` | number | undefined | The scaling factor in the y-direction (defaults to sx).
  `anchor` | Coordinate | undefined | The scale origin (defaults to the center of the geometry extent).

#### set(key, value, silent) inherited

Object.js, line 218

  Sets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `value` | * | Value.
  `silent` | boolean | undefined | Update without triggering an event.

#### setCenter(center)

geom/Circle.js, line 179

  Set the center of the circle as `coordinate`.

  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | Center.

#### setCenterAndRadius(center, radius, layout)

geom/Circle.js, line 199

  Set the center (as `coordinate`) and the radius (as number) of the circle.

  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | Center.
  `radius` | number | Radius.
  `layout` | GeometryLayout | undefined | Layout.

#### setProperties(values, silent) inherited

Object.js, line 238

  Sets a collection of key-value pairs. Note that this changes any existing properties and adds new ones (it does not remove any existing properties).

  Name | Type | Description
  --- | --- | ---
  `values` | Partial.<NoInfer.<Properties>> | Values.
  `silent` | boolean | undefined | Update without triggering an event.

#### setRadius(radius)

geom/Circle.js, line 232

  Set the radius of the circle. The radius is in the units of the projection.

  Name | Type | Description
  --- | --- | ---
  `radius` | number | Radius.

#### simplify(tolerance){Geometry} inherited

geom/Geometry.js, line 233

  Create a simplified version of this geometry. For linestrings, this uses the Douglas Peucker algorithm. For polygons, a quantization-based simplification is used to preserve topology.

  Name | Type | Description
  --- | --- | ---
  `tolerance` | number | The tolerance distance for simplification.

  ##### Returns:

  A new, simplified version of the original geometry.

#### transform(source, destination){Circle}

geom/Circle.js, line 277

  Transform each coordinate of the circle from one coordinate reference system to another. The geometry is modified in place. If you do not want the geometry modified in place, first clone() it and then use this function on the clone.

  Internally a circle is currently represented by two points: the center of the circle `[cx, cy]`, and the point to the right of the circle `[cx + r, cy]`. This `transform` function just transforms these two points. So the resulting geometry is also a circle, and that circle does not correspond to the shape that would be obtained by transforming every point of the original circle.

  Name | Type | Description
  --- | --- | ---
  `source` | ProjectionLike | The current projection. Can be a string identifier or a `Projection` object.
  `destination` | ProjectionLike | The desired projection. Can be a string identifier or a `Projection` object.

  ##### Returns:

  This geometry. Note that original geometry is modified in place.

#### translate(deltaX, deltaY) inherited

geom/SimpleGeometry.js, line 287

  Translate the geometry. This modifies the geometry coordinates in place. If instead you want a new geometry, first `clone()` this geometry.

  Name | Type | Description
  --- | --- | ---
  `deltaX` | number | Delta X.
  `deltaY` | number | Delta Y.

#### un(type, listener) inherited

Observable.js, line 173

  Unlisten for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

#### unset(key, silent) inherited

Object.js, line 262

  Unsets a property.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `silent` | boolean | undefined | Unset without triggering an event.