ArcObjects Library Reference (Geometry)  

IPolygon Interface

Provides access to members that identify a polygon and permit controlled access to its inner and outer rings. Note: the IPolygon interface has been superseded byIPolygon4. Please consider using the more recent version.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.


A polygon is a collection of one or many exterior and interior rings.  The rings do not need to be connected to or contained by other rings in the polygon.  However, all rings are considered to be part of a single polygon regardless of their location.  Rings can be embedded in the interior of other rings.  Embedded rings define interior boundaries or holes within the polygon.  Exterior rings are oriented in a clockwise direction while interior rings are oriented counterclockwise.


Method Close Closes all rings in this polygon. The resulting polygon may not be simple.
Method Densify Converts this polycurve into a piecewise linear approximation of itself.
Read-only property Dimension The topological dimension of this geometry.
Read-only property Envelope Creates a copy of this geometry's envelope and returns it.
Read-only property ExteriorRingCount The number of exterior rings.
Method FindExteriorRing Returns the exterior ring containing the specified interior ring.
Read/write property FromPoint The 'from' point of the curve.
Method Generalize Generalizes this polycurve using the Douglas-Poiker algorithm.
Read-only property GeometryType The type of this geometry.
Method GeoNormalize Shifts longitudes, if need be, into a continuous range of 360 degrees.
Method GeoNormalizeFromLongitude Normalizes longitudes into a continuous range containing the longitude. This method is obsolete.
Method GetSubcurve Extracts a portion of this curve into a new curve.
Read-only property InteriorRingCount The number of rings interior to the specified exterior ring.
Read-only property IsClosed Indicates if 'from' and 'to' points (of each part) are identical.
Read-only property IsEmpty Indicates whether this geometry contains any points.
Read-only property Length The length of the curve.
Method Project Projects this geometry into a new spatial reference.
Method QueryEnvelope Copies this geometry's envelope properties into the specified envelope.
Method QueryExteriorRings Populates an array with references to all exterior rings. This method does not marshall correctly out-of-proc. Use QueryExteriorRingsEx on the IPolygon2 interface instead.
Method QueryFromPoint Copies this curve's 'from' point to the input point.
Method QueryInteriorRings Populates an array with references to rings that are interior to the specified exterior ring. This method does not marshall correctly out-of-proc. Use QueryInteriorRingsEx on the IPolygon2 interface instead.
Method QueryNormal Constructs a line normal to a curve from a point at a specified distance along the curve.
Method QueryPoint Copies to outPoint the properties of a point on the curve at a specified distance from the beginning of the curve.
Method QueryPointAndDistance Finds the point on the curve closest to inPoint, then copies that point to outPoint; optionally calculates related items.
Method QueryTangent Constructs a line tangent to a curve from a point at a specified distance along the curve.
Method QueryToPoint Copies the curve's 'to' point into the input point.
Method ReverseOrientation Reverses the parameterization of the curve ('from' point becomes 'to' point, first segment becomes last segment, etc).
Method SetEmpty Removes all points from this geometry.
Method SimplifyPreserveFromTo Simplifies the polygon and maintains the index location of the from/to point of each ring.
Method Smooth Converts this curve into a smooth curve containing only Bezier curve segments.
Method SnapToSpatialReference Moves points of this geometry so that they can be represented in the precision of the geometry's associated spatial reference system.
Read/write property SpatialReference The spatial reference associated with this geometry.
Method SplitAtDistance Introduces a new vertex into this polyline at a specified distance from the beginning of the polyline.
Method SplitAtPoint Introduces a new vertex into this polyline at the location on it closest to the input point.
Read/write property ToPoint The 'to' point of the curve.
Method Weed Generalizes using a small tolerance based upon either the system units of the geometry's spatial reference, or the geometry's bounding box.

Inherited Interfaces

Interfaces Description
IPolycurve Provides access to members that define operations common to polylines and the boundaries of polygons.
ICurve Provides access to properties and methods of all 1 dimensional curves (polylines, segments, boundaries of polygons, etc.).
IGeometry Provides access to members that describe properties and behavior of all geometric objects.

CoClasses that implement IPolygon

CoClasses and Classes Description
GeoEllipse (esriDefenseSolutions) Its a spheroidal ellipse.
GeoPolygon (esriDefenseSolutions) Its a spheroidal polygon.
Polygon A collection of rings ordered by their containment relationship; optionally has measure, height and ID attributes.


To define a polygon containing many disjoint rings, the polygon must be defined as a GeometryCollection to which preconstructed ring geometries are added.  Adding segments to a polygon defined as a SegmentCollection, or points to a polygon defined as a PointCollection, assumes that the polygon is a single ring of connected segments.

IPolygon2 extends the functionality of IPolygon.


See Also

IGeometry Interface | IRing Interface | IPolycurve Interface | ISegmentCollection Interface | IGeometryCollection Interface | IPointCollection Interface

.NET Snippets

Cut Polygon

.NET Samples

3D multipatch examples (Code Files: CompositeExamples ExtrusionExamples) | Tabbed feature inspector (Code Files: TabbedInspector) | Geoevents in a MapControl (Code Files: GeoEvents) | Creating a toolbar of globe tools (Code Files: PolygonGeometry) | Buffer snap agent (Code Files: BufferSnap) | Custom subtyped command and tool (Code Files: PolyFeedbackTools) | Triangle graphic element (Code Files: TriangleElementClass) | Tabbed feature inspector (Code Files: ObjectInspector)

.NET Related Topics

Creating a topology in the geodatabase | Geodatabase | Geodetic curve support in the ArcObjects Geometry API | How to build a polygon using segments and points | How to create a multipoint | How to create a polygon | How to create a polyline | How to create a union of several polygons | How to work with IExtrude | Implementing persistence | Performing map selection | Selection trackers | Working with the edit sketch