Graphics.DrawCurve Method (Pen, Point(), Single)


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Draws a cardinal spline through a specified array of Point structures using a specified tension.

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

Public Sub DrawCurve (
	pen As Pen,
	points As Point(),
	tension As Single


Type: System.Drawing.Pen

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

Type: System.Drawing.Point()

Array of Point structures that define the spline.

Type: System.Single

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

Exception Condition

pen is null.


points is null.

This method draws a cardinal spline that passes through each point in the array.

The array of points must contain at least three Point structures for a curve to be drawn.

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 six red straight lines between the seven points to form an incomplete polygon.

  • Creates a tension setting.

  • Draws an open green closed curve through the seven points.

The method uses a tension of 1.0.

Private Sub DrawCurvePointTension(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 Point(50, 50)
    Dim point2 As New Point(100, 25)
    Dim point3 As New Point(200, 5)
    Dim point4 As New Point(250, 50)
    Dim point5 As New Point(300, 100)
    Dim point6 As New Point(350, 200)
    Dim point7 As New Point(250, 250)
    Dim curvePoints As Point() = {point1, point2, point3, point4, _
    point5, point6, point7}

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

    ' Create tension.
    Dim tension As Single = 1.0F

    ' Draw curve to screen.
    e.Graphics.DrawCurve(greenPen, curvePoints, tension)
End Sub

.NET Framework
Available since 1.1
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