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Graphics.DrawClosedCurve Method (Pen, Point[], Single, FillMode)

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

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

public void DrawClosedCurve(
	Pen pen,
	Point[] points,
	float tension,
	FillMode fillmode
)

Parameters

pen
Type: System.Drawing.Pen

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

points
Type: System.Drawing.Point[]

Array of Point 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 ignored.

ExceptionCondition
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 Point 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 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 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 void DrawClosedCurvePointTension(PaintEventArgs e)
{

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

    // Create points that define curve.
    Point point1 = new Point(50, 50);
    Point point2 = new Point(100, 25);
    Point point3 = new Point(200, 5);
    Point point4 = new Point(250, 50);
    Point point5 = new Point(300, 100);
    Point point6 = new Point(350, 200);
    Point point7 = new Point(250, 250);
    Point[] curvePoints = {point1, point2, point3, point4, point5, point6, point7};

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

    // Create tension and fill mode. 
    float tension = 1.0F;
    FillMode aFillMode = FillMode.Alternate;

    // Draw closed curve to screen.
    e.Graphics.DrawClosedCurve(greenPen, curvePoints, tension, aFillMode);
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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