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Graphics.DrawCurve Method (Pen, PointF[], Int32, Int32)

Draws a cardinal spline through a specified array of PointF structures. The drawing begins offset from the beginning of the array.

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

public void DrawCurve(
	Pen pen,
	PointF[] points,
	int offset,
	int numberOfSegments
)

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.

offset
Type: System.Int32

Offset from the first element in the array of the points parameter to the starting point in the curve.

numberOfSegments
Type: System.Int32

Number of segments after the starting point to include in the curve.

ExceptionCondition
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 value of the offset parameter specifies the number of elements to skip in the array. The first element after the skipped elements represents the starting point of the curve.

The value of the numberOfSegments parameter specifies the number of segments, after the starting point, to draw in the curve. The value of the numberOfSegments parameter must be at least 1. The value of the offset parameter plus the value of the numberOfSegments parameter must be less than the number of elements in the array of the points parameter.

This method uses a default tension of 0.5.

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 a curve.

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

  • Defines the starting point offset and number of segments.

  • Draws an open green curve (starting at the third point) through the last five points.

The method uses a default tension of 0.5.

private void DrawCurvePointFSegments(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 offset and number of segments. 
    int offset = 2;
    int numSegments = 4;

    // Draw curve to screen.
    e.Graphics.DrawCurve(greenPen, curvePoints, offset, numSegments);
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

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

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