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
)

Parameters

pen
Type: System.Drawing.Pen

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

points
Type: System.Drawing.PointF[]

Array of PointF structures that represent the points that define the curve.

tension
Type: System.Single

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

Exception Condition
ArgumentNullException

pen is null.

-or-

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 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 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
Available since 1.1
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