Provides access to members that control properties of elliptic arc segments.
Description
An Elliptic Arc is an object that describes any portion of an ellipse. The Major axis of the Elliptic Arc is the largest axis spanning between points on opposite sides of the ellipse. The Minor axis is the perpendicular bisector of the Major axis. Together, the Major and Minor axes determine the full ellipse on which the Elliptic Arc is generated. These parameters may also be specified in terms of the semi-Major axis (half of the Major axis) and the MinorMajorRatio (the ratio of the Minor axis to the Major axis). The ellipse may also be rotated. Rotation is described by the Rotation Angle. However, the effect of the Rotation Angle depends on the value of EllipseStd. If EllipseStd is TRUE, all angles and axes are calculated with respect to the Major Axis as though the Major Axis was at 0 radians. Also, the location of the From Point and To Point are given relative to the Center Point as though it is the origin. If EllipseStd is FALSE, all angles are caluclated in standard Cartesian coordinates. The portion of the complete ellipse represented by the Elliptic Arc is determined by the From Angle and Central Angle, both measured in radians.
Members
| Name | Description | |
|---|---|---|
 |
CenterPoint | The center point of the arc. |
 |
CentralAngle | The included (or central) angle. |
 |
Complement | Changes this ellipse into its complement; 'from' and 'to' points are unchanged. |
|
Dimension | The topological dimension of this geometry. |
|
Envelope | Creates a copy of this geometry's envelope and returns it. |
|
FromAngle | The start angle (measured from a horizontal line through the center point) defining where the arc starts. |
|
FromPoint | The 'from' point of the curve. |
|
GeometryType | The type of this geometry. |
|
GeoNormalize | Shifts longitudes, if need be, into a continuous range of 360 degrees. |
|
GeoNormalizeFromLongitude | Normalizes longitudes into a continuous range containing the longitude. This method is obsolete. |
|
GetAxes | Gets the semi-major and semi-minor axes. |
|
GetSubcurve | Extracts a portion of this curve into a new curve. |
|
IsCircular | Indicates if this elliptical arc is acutally circular (major and minor axes same length). |
|
IsClosed | Indicates if 'from' and 'to' points (of each part) are identical. |
|
IsCounterClockwise | Indicates if this elliptic arc is oriented counter-clockwise from its 'from' point to its 'to' point. |
|
IsEmpty | Indicates whether this geometry contains any points. |
|
IsLine | Indicates if the arc is degenerated to a line. |
|
IsMinor | Indicates whether the arc is a minor arc or a major arc. |
|
IsPoint | Indicates if the arc is degenerated to a point. |
|
Length | The length of the curve. |
|
Project | Projects this geometry into a new spatial reference. |
|
PutAxes | Sets the semi-major and semi-minor axes. |
|
PutCoords | Sets the center point and endpoints, angle of rotation, and orientation. |
|
PutCoordsByAngle | Sets the center point, starting angle, signed central angle, angle of rotation, ratio of the minor axis to the major axis, and axes. |
|
QueryCenterPoint | Copies the center of this arc to the input point. |
|
QueryCoords | Copies the center and endpoints, angle of rotation, orientation and major/minor properties into the method parameters. |
|
QueryCoordsByAngle | Returns the center point, starting angle, signed central angle, angle of rotation, ratio of the minor axis to the major axis, and axes. |
|
QueryEnvelope | Copies this geometry's envelope properties into the specified envelope. |
|
QueryFromPoint | Copies this curve's 'from' point to the input point. |
|
QueryNormal | Constructs a line normal to a curve from a point at a specified distance along the curve. |
|
QueryPoint | Copies to outPoint the properties of a point on the curve at a specified distance from the beginning of the curve. |
|
QueryPointAndDistance | Finds the point on the curve closest to inPoint, then copies that point to outPoint; optionally calculates related items. |
|
QueryTangent | Constructs a line tangent to a curve from a point at a specified distance along the curve. |
|
QueryToPoint | Copies the curve's 'to' point into the input point. |
|
ReverseOrientation | Reverses the parameterization of the curve ('from' point becomes 'to' point, first segment becomes last segment, etc). |
|
SetEmpty | Removes all points from this geometry. |
|
SnapToSpatialReference | Moves points of this geometry so that they can be represented in the precision of the geometry's associated spatial reference system. |
 |
SpatialReference | The spatial reference associated with this geometry. |
|
ToAngle | The end angle (measured from a horizontal line through the center point) defining where the arc ends. |
|
ToPoint | The 'to' point of the curve. |
IEllipticArc.CenterPoint Property
The center point of the arc.
Public ReadOnly Property CenterPoint As IPoint
public IPoint CenterPoint {get;}
Description
The CenterPoint is the point where the Major Axis and Minor Axis of the EllipticArc intersect. The CenterPoint is the point from which all angles and distances are calculated to create the EllipticArc.
Remarks
IEllipticArc.CentralAngle Property
The included (or central) angle.
Public Property CentralAngle As Double
public double CentralAngle {get; set;}
Description
The CentralAngle describes the span of the EllipticArc. The CentralAngle is the angular measure between the FromAngle and the ToAngle. The CentralAngle is measured in Radians and is always between -2*Pi and 2*Pi. If the CentralAngle > 0, then the EllipticArc is oriented in a CounterClockwise direction.
Remarks
IEllipticArc.Complement Method
Changes this ellipse into its complement; 'from' and 'to' points are unchanged.
Public Sub Complement ( _
)
public void Complement (
);
Description
The Complement of an EllipticArc is the EllipticArc between the ToPoint and the FromPoint of the original EllipticArc that creates a full ellipse when combined with the original EllipticArc. The Complement maintains the same FromPoint and ToPoint as the original EllipticArc, but has the different IsMinor and IsCounterClockwise values.
Remarks
IEllipticArc.FromAngle Property
The start angle (measured from a horizontal line through the center point) defining where the arc starts.
Public Function get_FromAngle ( _
ByVal ellipseStd As Boolean _
) As Double
Public Sub set_FromAngle ( _
ByVal ellipseStd As Boolean, _
ByVal FromAngle As Double _
)
public double get_FromAngle (
bool ellipseStd
);
public void set_FromAngle (
bool ellipseStd,
double FromAngle
);
Description
The From Angle is the angle of the Line defined by the Center Point and the From Point of the Elliptic Arc. Setting the From Angle changes the From Point of the Elliptic Arc without altering the embedded geometry. The From Angle is measured in radians (there are 2*pi radians in a full ellipse). If EllipseStd = TRUE, the From Angle is relative to the rotated semi-Major Axis rather than the X-Axis.
Remarks
IEllipticArc.GetAxes Method
Gets the semi-major and semi-minor axes.
Public Sub GetAxes ( _
ByRef semiMajor As Double, _
ByRef semiMinor As Double, _
ByRef minorMajorRatio As Double _
)
public void GetAxes (
ref double semiMajor,
ref double semiMinor,
ref double minorMajorRatio
);
Description
Returns the Major Axis, the Minor Axis, and the ratio of the Minor Axis to the Major Axis. The Major Axis is the larger of the two Axes, and the Minor Axis is the smaller Axis. The Major Axis always lies on the line between 0 and Pi Radians in EllipseStd, and the Minor Axis always lies on the line between Pi/2 and 3*Pi/2 Radian in EllipseStd.
Remarks
The Axes can be set using PutAxes.
IEllipticArc.IsCircular Property
Indicates if this elliptical arc is acutally circular (major and minor axes same length).
Public ReadOnly Property IsCircular As Boolean
public bool IsCircular {get;}
Description
IsCircular returns TRUE when the minorMajorRatio = 1.
IEllipticArc.IsCounterClockwise Property
Indicates if this elliptic arc is oriented counter-clockwise from its 'from' point to its 'to' point.
Public Property IsCounterClockwise As Boolean
public bool IsCounterClockwise {get; set;}
Description
IsCounterClockwise returns TRUE if the CentralAngle is greater than 0. If the IsCounterClockwise values differ, setting IsCounterClockwise changes the EllipticArc to its Complement.
Remarks
IEllipticArc.IsLine Property
Indicates if the arc is degenerated to a line.
Public ReadOnly Property IsLine As Boolean
public bool IsLine {get;}
Description
IsLine returns TRUE when the minorMajorRatio = 0. This is analgous to the semiMinor Axis having a length of 0.
Remarks
IEllipticArc.IsMinor Property
Indicates whether the arc is a minor arc or a major arc.
Public Property IsMinor As Boolean
public bool IsMinor {get; set;}
Description
IsMinor is TRUE when the CentralAngle < Pi (180 degrees). IsMinor also returns TRUE when the semiMajor axis = 0. If the IsMinor values differ, setting IsMinor changes the EllipticArc to its Complement.
Remarks
IEllipticArc.IsPoint Property
Indicates if the arc is degenerated to a point.
Public ReadOnly Property IsPoint As Boolean
public bool IsPoint {get;}
Description
IsPoint returns TRUE when the semiMajor axis = 0. IsPoint returns FALSE when the semiMajor axis > 0 (this includes when the CentralAngle = 0, as this is a well-defined EllipticArc.).
IEllipticArc.PutAxes Method
Sets the semi-major and semi-minor axes.
Public Sub PutAxes ( _
ByVal semiMajor As Double, _
ByVal minorMajorRatio As Double _
)
public void PutAxes (
double semiMajor,
double minorMajorRatio
);
Description
Sets the Major Axis and the Minor Axis. The Major Axis is the larger of the two Axes, and the Minor Axis is the smaller Axis. The Major Axis always lies on the line between 0 and Pi Radians in EllipseStd, and the Minor Axis always lies on the line between Pi/2 and 3*Pi/2 Radian in EllipseStd.
Remarks
The Axes can be returned using GetAxes.
IEllipticArc.PutCoords Method
Sets the center point and endpoints, angle of rotation, and orientation.
Public Sub PutCoords ( _
ByVal ellipseStd As Boolean, _
ByVal Center As IPoint, _
ByVal from As IPoint, _
ByVal to As IPoint, _
ByVal rotationAngle As Double, _
ByVal minorMajorRatio As Double, _
ByVal orientation As esriArcOrientation _
)
public void PutCoords (
bool ellipseStd,
IPoint Center,
IPoint from,
IPoint to,
double rotationAngle,
double minorMajorRatio,
esriArcOrientation orientation
);
Description
PutCoords creates an Elliptic Arc given the EllipseStd value, Center Point, From Point, To Point, Rotation Angle, Minor Axis to Major Axis Ratio, and the Arc Orientation. If EllipseStd = TRUE, the From Point and To Point locations are relative offsets from the Center Point rather than the origin.
Remarks
Unless the coordinates of the From and To Points are exactly on the defined Elliptic Arc, PutCoords is likely to create an invalid Elliptic Arc. Therefore, it is highly recommended that another Elliptic Arc creation method is used unless all of the necessary input parameters are exactly known.
IEllipticArc.PutCoordsByAngle Method
Sets the center point, starting angle, signed central angle, angle of rotation, ratio of the minor axis to the major axis, and axes.
Public Sub PutCoordsByAngle ( _
ByVal ellipseStd As Boolean, _
ByVal Center As IPoint, _
ByVal FromAngle As Double, _
ByVal CentralAngle As Double, _
ByVal rotationAngle As Double, _
ByVal semiMajor As Double, _
ByVal minorMajorRatio As Double _
)
public void PutCoordsByAngle (
bool ellipseStd,
IPoint Center,
double FromAngle,
double CentralAngle,
double rotationAngle,
double semiMajor,
double minorMajorRatio
);
Description
Creates an Elliptic Arc given the EllipseStd value, Center Point, From Angle, Central Angle, Rotation Angle, semi-Major Axis length, and Minor Axis to Major Axis Ratio. If EllipseStd = TRUE, the From Angle is relative to the rotated semi-Major Axis rather than the X-Axis.
Remarks
This is the recommended way to create an arbitrary Elliptic Arc. However, due to numeric accuracy limitations of computers and trigonometric functions, the From and To Points may be very slightly offset from the expected coordinates. This is important to keep in mind when attempting to connect the endpoints to other segments.
IEllipticArc.QueryCenterPoint Method
Copies the center of this arc to the input point.
Public Sub QueryCenterPoint ( _
ByVal Center As IPoint _
)
public void QueryCenterPoint (
IPoint Center
);
Description
The CenterPoint is the point where the Major Axis and Minor Axis of the EllipticArc intersect. The CenterPoint is the point from which all angles and distances are calculated to create the EllipticArc. You must instantiate the Point before calling QueryCenterPoint. For example,
Dim pPoint as IPoint
Set pPoint = New Point
Remarks
The QueryCenterPoint method should be used in performance critical situations, where the center point of several arcs needs to be retrieved. The point is populated (not created) by the method. For example, this can be used to get the center point of several arcs in a loop. Creating the point only once outside the loop may improve performance for large number of arcs.
//This example demonstrates how to use the QueryCenterPoint method
private void QueryCenterPoint()
{
IPoint center = new PointClass();
center.PutCoords(10, 10);
IEllipticArc ellipticArc = new EllipticArcClass();
ellipticArc.PutCoordsByAngle(false, center, 0, Math.PI / 2, 0, 20, 0.4);
//Cocreate the center point
IPoint theCenterPoint = new PointClass();
ellipticArc.QueryCenterPoint(theCenterPoint);
System.Windows.Forms.MessageBox.Show("Center point coordinates \n" + theCenterPoint.X + ", " + theCenterPoint.Y);
}
'This example demonstrates how to use the QueryCenterPoint method
Sub QueryCenterPoint_example()
Dim pEArc As IEllipticArc, dpi As Double
Dim pCenter As IPoint, pTheCenterPoint As IPoint
dpi = Math.Atan(1) * 4
pCenter = New Point
pEArc = New EllipticArc
pCenter.PutCoords(10, 10)
pEArc.PutCoordsByAngle(False, pCenter, 0, dpi / 2, 0, 20, 0.4)
'Cocreate the center point
pTheCenterPoint = New Point
pEArc.queryCenterPoint(pTheCenterPoint)
Debug.Print("Center point coordinates")
Debug.Print(pTheCenterPoint.X & " , " & pTheCenterPoint.Y)
End Sub
IEllipticArc.QueryCoords Method
Copies the center and endpoints, angle of rotation, orientation and major/minor properties into the method parameters.
Public Sub QueryCoords ( _
ByVal ellipseStd As Boolean, _
ByVal Center As IPoint, _
ByVal from As IPoint, _
ByVal to As IPoint, _
ByRef rotationAngle As Double, _
ByRef minorMajorRatio As Double, _
ByRef isCCW As Boolean, _
ByRef minor As Boolean _
)
public void QueryCoords (
bool ellipseStd,
IPoint Center,
IPoint from,
IPoint to,
ref double rotationAngle,
ref double minorMajorRatio,
ref bool isCCW,
ref bool minor
);
Description
Given the EllipseStd value, returns the Center Point, From Point, To Point, Rotation Angle, Minor Axis to Major Axis Ratio, IsCounterClockwise value, and IsMinor value of the Elliptic Arc. If EllipseStd = TRUE, the From Point and To Point locations are relative offsets from the Center Point rather than the origin.
Remarks
These are the necessary inputs for PutCoords, except in special cases (half ellipse, full ellipse, Central Angle = 0, and Minor to Major Ratio = 0) where the ArcOrientation must know which of these cases exists to ensure that the desired Elliptic Arc is unambiguous. Any of the output parameters can be set to nil if that info is not desired.
-isCCW stands for "is counter clockwise"
IEllipticArc.QueryCoordsByAngle Method
Returns the center point, starting angle, signed central angle, angle of rotation, ratio of the minor axis to the major axis, and axes.
Public Sub QueryCoordsByAngle ( _
ByVal ellipseStd As Boolean, _
ByVal Center As IPoint, _
ByRef FromAngle As Double, _
ByRef CentralAngle As Double, _
ByRef rotationAngle As Double, _
ByRef semiMajor As Double, _
ByRef minorMajorRatio As Double _
)
public void QueryCoordsByAngle (
bool ellipseStd,
IPoint Center,
ref double FromAngle,
ref double CentralAngle,
ref double rotationAngle,
ref double semiMajor,
ref double minorMajorRatio
);
Description
Given the EllipseStd value, returns the Center Point, From Angle, Central Angle, Rotation Angle, semi-Major axis length, and Minor Axis to Major Axis Ratio for the Elliptic Arc. These are the same parameters used by PutCoordsByAngle to create the Elliptic Arc. If EllipseStd = TRUE, the From Angle is relative to the rotated semi-Major Axis rather than the X-Axis.
Remarks
IEllipticArc.ToAngle Property
The end angle (measured from a horizontal line through the center point) defining where the arc ends.
Public Function get_ToAngle ( _
ByVal ellipseStd As Boolean _
) As Double
Public Sub set_ToAngle ( _
ByVal ellipseStd As Boolean, _
ByVal ToAngle As Double _
)
public double get_ToAngle (
bool ellipseStd
);
public void set_ToAngle (
bool ellipseStd,
double ToAngle
);
Description
The To Angle is the angle of the Line defined by the Center Point and the To Point of the Elliptic Arc. Setting the To Angle changes the To Point of the Elliptic Arc without altering the embedded geometry. The To Angle is measured in radians (there are 2*pi radians in a full ellipse). If EllipseStd = TRUE, the To Angle is relative to the rotated semi-Major Axis rather than the X-Axis.
Remarks
Inherited Interfaces
| Interfaces | Description |
|---|---|
| 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. |
Classes that implement IEllipticArc
| Classes | Description |
|---|---|
| EllipticArc | A portion of the boundary of a 2D ellipse that connects two points; optionally has measure, height and ID attributes at each endpoint. |
Remarks
A CircularArc is a special case of an EllipticArc where the MinorMajorRatio is 1 (however, a CircularArc is NOT an EllipticArc).