Graphics::DrawClosedCurve Method (Pen^, array<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)

void DrawClosedCurve(
	Pen^ pen,
	array<Point>^ points,
	float tension,
	FillMode fillmode


Type: System.Drawing::Pen^

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

Type: array<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.

Type: System.Drawing.Drawing2D::FillMode

Member of the FillMode enumeration that determines how the curve is filled. This parameter is required but ignored.

Exception Condition

pen is null.


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 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 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.

   void DrawClosedCurvePointTension( PaintEventArgs^ e )
      // Create pens.
      Pen^ redPen = gcnew Pen( Color::Red,3.0f );
      Pen^ greenPen = gcnew Pen( Color::Green,3.0f );

      // Create points that define curve.
      Point point1 = Point(50,50);
      Point point2 = Point(100,25);
      Point point3 = Point(200,5);
      Point point4 = Point(250,50);
      Point point5 = Point(300,100);
      Point point6 = Point(350,200);
      Point point7 = Point(250,250);
      array<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
Available since 1.1
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