Graphics.DrawClosedCurve Method (Pen, PointF(), Single, FillMode)

 
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Draws a closed cardinal spline defined by an array of PointF structures using a specified tension.

Namespace:   System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

Public Sub DrawClosedCurve (
	pen As Pen,
	points As PointF(),
	tension As Single,
	fillmode As FillMode
)

Parameters

pen
Type: System.Drawing.Pen

Pen that determines the color, width, and height of the curve.

points
Type: System.Drawing.PointF()

Array of PointF structures that define the spline.

tension
Type: System.Single

Value greater than or equal to 0.0F that specifies the tension of the curve.

fillmode
Type: System.Drawing.Drawing2D.FillMode

Member of the FillMode enumeration that determines how the curve is filled. This parameter is required but is ignored.

Exception Condition
ArgumentNullException

pen is null.

-or-

points is null.

This method draws a closed cardinal spline that passes through each point in the array. If the last point does not match the first point, an additional curve segment is added from the last point to the first point to close it.

The array of points must contain at least four PointF structures.

The tension parameter determines the shape of the spline. If the value of the tension parameter is 0.0F, this method draws straight line segments to connect the points. Usually, the tension parameter is less than or equal to 1.0F. Values over 1.0F produce unusual results.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgse, which is a parameter of the Paint event handler. The code performs the following actions:

  • Creates red and green pens.

  • Creates seven points to define the curve.

  • Draws seven red straight lines between the seven points to form a polygon.

  • Creates tension and fill mode settings.

  • Draws a green closed curve through the seven points.

The method uses a tension of 1.0 and sets the fill mode to FillMode.Alternate.

Private Sub DrawClosedCurvePointFTension(ByVal e As PaintEventArgs)

    ' Create pens.
    Dim redPen As New Pen(Color.Red, 3)
    Dim greenPen As New Pen(Color.Green, 3)

    ' Create points that define curve.
    Dim point1 As New PointF(50.0F, 50.0F)
    Dim point2 As New PointF(100.0F, 25.0F)
    Dim point3 As New PointF(200.0F, 5.0F)
    Dim point4 As New PointF(250.0F, 50.0F)
    Dim point5 As New PointF(300.0F, 100.0F)
    Dim point6 As New PointF(350.0F, 200.0F)
    Dim point7 As New PointF(250.0F, 250.0F)
    Dim curvePoints As PointF() = {point1, point2, point3, point4, _
    point5, point6, point7}

    ' Draw lines between original points to screen.
    e.Graphics.DrawLines(redPen, curvePoints)

    ' Create tension and fill mode.
    Dim tension As Single = 1.0F
    Dim aFillMode As FillMode = FillMode.Alternate

    ' Draw closed curve to screen.
    e.Graphics.DrawClosedCurve(greenPen, curvePoints, tension, _
    aFillMode)
End Sub

.NET Framework
Available since 1.1
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