GraphicBuffer(IEnumerable<Geometry>,Double,LineJoinType,LineCapType,Double,Double,Int32) Method

Creates a buffer polygon at the specified distance around the input geometry using graphical joins and caps.

Syntax

C#
Visual Basic (Declaration)

IReadOnlyList<Geometry> GraphicBuffer( 
   IEnumerable<Geometry> geometries,
   double distance,
   LineJoinType joins,
   LineCapType caps,
   double miterLimit,
   double maxDeviation,
   int maxVerticesInFullCircle
)

Overloads Function GraphicBuffer( _
   ByVal geometries As IEnumerable(Of Geometry), _
   ByVal distance As Double, _
   ByVal joins As LineJoinType, _
   ByVal caps As LineCapType, _
   ByVal miterLimit As Double, _
   ByVal maxDeviation As Double, _
   ByVal maxVerticesInFullCircle As Integer _
) As IReadOnlyList(Of Geometry)

Parameters

geometries: The geometries to buffer
distance: The buffer distance in the unit of the geometry's spatial reference
joins: The line joins
caps: The line caps
miterLimit: The threshold determining when miter joins are replaced with the bevel joins. Use a value of 4 for a good default.
maxDeviation: The max deviation of the result buffer from the true buffer in the units of the spatial reference. When maxDeviation is NaN or 0, it is replaced with 1e-5 * abs(distance). When maxDeviation is larger than MIN = 0.5 * abs(distance), it is replaced with MIN. See the remarks section for more information.
maxVerticesInFullCircle: The maximum number of vertices in round polygon produced from a buffered point. A value of 96 is used in methods that do not accept maxVerticesInFullCircle. If the value is less than MIN = 12, it is set to MIN. See the remarks section for more information.

Return Value

List of geometries representing the graphic buffers

Exceptions

Exception	Description
System.ArgumentNullException	Geometries is null or empty
System.NotImplementedException	The method is not implemented for GeometryBag or Multipatch.
System.ArgumentException	The buffer distance must be a valid floating point number.

Remarks

The spatial reference of the output geometries is the first not null or Unknown spatial reference found in the list of geometries. All other geometries are projected to this spatial reference, if necessary. If no such spatial reference is found, then the Unknown spatial reference is used if it is found in the list. Otherwise, the spatial reference is null.

The maxDeviation and maxVerticesInFullCircle control the quality of round joins in the buffer. That is, the precision of the buffer is maxDeviation unless the number of required vertices is too large. The maxVerticesInFullCircle controls how many vertices can be in each round join in the buffer. It is approximately equal to the number of vertices in the polygon around a buffered point. It has a priority over maxDeviation. The max deviation is the distance from the result polygon to a true buffer. The real deviation is calculated as the max(maxDeviation, abs(distance) (1 - cos(PI / maxVerticesInFullCircle))).

Note that maxDeviation can be exceeded because geometry is generalized with 0.25 times the real deviation, also input segments closer than 0.25 real deviation are snapped to a point.

Note, this operator is equivalent to GeometryEngine.Buffer when the joins and caps are round.

See stroke-miterlimit, stroke-linejoin, stroke-linecap parameters in the SVG specification for more info on the graphical parameters.

Example

// round join and round caps
MapPoint point1 = MapPointBuilder.CreateMapPoint(0, 0);
MapPoint point2 = MapPointBuilder.CreateMapPoint(1, 1, SpatialReferences.WGS84);
MapPoint point3 = MapPointBuilder.CreateMapPoint(1000000, 1200000, SpatialReferences.WebMercator);
List<MapPoint> points = new List<MapPoint>() { point1, point2, point3 };

IReadOnlyList<Geometry> geometries = GeometryEngine.Instance.GraphicBuffer(points, 5, LineJoinType.Round, LineCapType.Round, 0, 0, 3000);

Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

Reference

IGeometryEngine Interface
IGeometryEngine Members
Overload List