import * as offsetOperator from "@arcgis/core/geometry/operators/offsetOperator.js";
const offsetOperator = await $arcgis.import("@arcgis/core/geometry/operators/offsetOperator.js");
@arcgis/core/geometry/operators/offsetOperator
Offset 2D geometries. The offset operation creates a geometry that is a constant distance from an input polyline or polygon. It is similar to buffering, but produces a one-sided result. Point and multipoint geometries are not supported.
The offset distance can be positive or negative, and it will have the following effects based on the input geometry types. This is also dependent on the input polygon being Esri simple.
| Geometry type | positive offset | negative offset |
|---|---|---|
| Polyline | To the right | To the left |
| Extent | Expands | Contracts |
| Polygon exterior ring (Esri simple) | Expands exterior | Contracts exterior |
| Polygon interior ring (Esri simple) | Contracts interior | Expands interior |
If the input polygon is not simple, then the offset geometry will be produced to the right or left as though the ring were a polyline and dependent on the ring's orientation. For a simple polygon, the orientation of outer rings is clockwise and for inner rings it is counter clockwise. So the right side of a simple polygon is always its inside.
The miter limit is multiplied by the offset distance and the result determines how far a mitered offset intersection can be from the input curve before it is beveled.
Join types
The join type controls how corners in the offset geometry are represented. Inner corners are always mitered. The following join types are supported:
- Round - a circular arc that is tangent to the ends of both offset line segments.
- Miter - the offset line segments are extended to their intersection point forming a sharp angle, unless that extension exceeds the
miterLimit, in which case the result is a bevel.
- Bevel - the offset line segments are not extended; their endpoints are joined by a straight line.
- Square - same as
miterfor minor arcs greater than 90 degrees. For all other minor arcs, the offset line segments are extended by an extradistancebefore their endpoints are joined.
Property Overview
| Name | Type | Summary | Object |
|---|---|---|---|
Indicates if the operator supports input geometries that contain curves. | offsetOperator |
Property Details
-
supportsCurves
PropertysupportsCurves Booleanreadonly -
Indicates if the operator supports input geometries that contain curves. The value will always be
true. This will produce densified output geometries.
Method Overview
| Name | Return Type | Summary | Object |
|---|---|---|---|
Creates an offset version of the input geometry. | offsetOperator | ||
Creates offset versions of the input geometries. | offsetOperator |
Method Details
-
execute
Methodexecute(geometry, distance, options){GeometryUnion |null |undefined} -
Creates an offset version of the input geometry. This is not applicable to point geometries.
ParametersSpecificationgeometry GeometryUnionThe input geometry. Can be an extent, polyline, or polygon. Point and multipoint geometries are not supported.
distance NumberThe distance to offset the input geometry. Unless the
unitoption is set, the default is the geometry's spatial reference unit.options ObjectoptionalAdditional options.
SpecificationflattenError NumberoptionalDefault Value: 0The maximum distance of the resulting segments compared to the true circular arc (used only when
joinsis set to"round"). The algorithm never produces more than around 180 vertices for each round join.joins StringoptionalDefault Value: "round"Defines the join type of the offset geometry. Inner corners are always mitered.
- Round - a circular arc that is tangent to the ends of both offset line segments.
- Miter - the offset line segments are extended to their intersection point forming a sharp angle, unless that extension exceeds the
miterLimit, in which case the result is a bevel. - Bevel - the offset line segments are not extended; their endpoints are joined by a straight line.
- Square - same as
miterfor minor arcs greater than 90 degrees. For all other minor arcs, the offset line segments are extended by an extradistancebefore their endpoints are joined.
Possible Values:"round"|"miter"|"bevel"|"square"
miterLimit NumberoptionalDefault Value: 10Applicable only to mitered joins. Controls the appearance of angled lines to avoid excessively long and pointy corners. The miterLimit is multiplied by the offset distance and the result is the maximum mitered offset: joins which would result in a larger mitered offset will be beveled instead.
unit LengthUnitoptionalThe length unit of the offset distance. The default is the input geometry's spatial reference unit. An error will be thrown if this is set for Geographic Coordinate Systems.
ReturnsType Description GeometryUnion | null | undefined Returns the offset geometry or null. Very acute angles can return null when an offset geometry segment cannot be created with the given parameters. Example// Create an offset polygon. const offsetPolygon = offsetOperator.execute(polygon, 100);
-
executeMany
MethodexecuteMany(geometries, distance, options){Array<(GeometryUnion|null|undefined)>} -
Creates offset versions of the input geometries.
ParametersSpecificationgeometries GeometryUnion[]The set of input geometries. Can be extents, polylines, or polygons. Point and multipoint geometries are not supported. All the geometries must have the same spatial reference.
distance NumberThe distance to offset the input geometries. Unless the
unitoption is set, the default is the geometries spatial reference unit.options ObjectoptionalAdditional options.
SpecificationflattenError NumberoptionalDefault Value: 0The maximum distance of the resulting segments compared to the true circular arc (used only when joins is round). The algorithm never produces more than around 180 vertices for each round join.
joins StringoptionalDefault Value: "round"Defines the join type of the offset geometry. Inner corners are always mitered.
- Round - a circular arc that is tangent to the ends of both offset line segments.
- Miter - the offset line segments are extended to their intersection point forming a sharp angle, unless that extension exceeds the
miterLimit, in which case the result is a bevel. - Bevel - the offset line segments are not extended; their endpoints are joined by a straight line.
- Square - same as
miterfor minor arcs greater than 90 degrees. For all other minor arcs, the offset line segments are extended by an extradistancebefore their endpoints are joined.
Possible Values:"round"|"miter"|"bevel"|"square"
miterLimit NumberoptionalDefault Value: 10Applicable only to mitered joins. Controls the appearance of angled lines to avoid excessively long and pointy corners. The miterLimit is multiplied by the offset distance and the result is the maximum mitered offset: joins which would result in a larger mitered offset will be beveled instead.
unit LengthUnitoptionalThe length unit of the offset distance. The default is the input geometries spatial reference unit. An error will be thrown if this is set for Geographic Coordinate Systems.
ReturnsType Description Array<(GeometryUnion|null|undefined)> Returns the offset geometry results or null. Very acute angles can return null when an offset geometry segment cannot be created with the given parameters.