DrawCurve Method (Pen, PointF[], Single)

Graphics.DrawCurve Method (Pen, PointF[], Single)

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

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

public void DrawCurve(
	Pen pen,
	PointF[] points,
	float tension


Type: System.Drawing.Pen
Pen that determines the color, width, and height of the curve.
Type: System.Drawing.PointF[]
Array of PointF structures that represent the points that define the curve.
Type: System.Single
Value greater than or equal to 0.0F that specifies the tension of the curve.


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 PointF 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 PaintEventArgs e, 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 void DrawCurvePointFTension(PaintEventArgs e)

    // Create pens.
    Pen redPen = new Pen(Color.Red, 3);
    Pen greenPen = new Pen(Color.Green, 3);

    // Create points that define curve.
    PointF point1 = new PointF(50.0F, 50.0F);
    PointF point2 = new PointF(100.0F, 25.0F);
    PointF point3 = new PointF(200.0F, 5.0F);
    PointF point4 = new PointF(250.0F, 50.0F);
    PointF point5 = new PointF(300.0F, 100.0F);
    PointF point6 = new PointF(350.0F, 200.0F);
    PointF point7 = new PointF(250.0F, 250.0F);
    PointF[] curvePoints = {point1, point2, point3, point4, point5, point6, point7};

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

    // Create tension.
    float tension = 1.0F;

    // Draw curve to screen.
    e.Graphics.DrawCurve(greenPen, curvePoints, tension);

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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