GraphicsPath::AddCurve(constPoint*,INT,INT,INT,REAL) method (gdipluspath.h)

The GraphicsPath::AddCurve method adds a cardinal spline to the current figure of this path.


Status AddCurve(
  [in] const Point *points,
  [in] INT         count,
  [in] INT         offset,
  [in] INT         numberOfSegments,
  [in] REAL        tension


[in] points

Type: const Point*

Pointer to an array of points that define the cardinal spline. The cardinal spline is a curve that passes through a subset (specified by the offset and numberOfSegments parameters) of the points in the array.

[in] count

Type: INT

Integer that specifies the number of elements in the points array.

[in] offset

Type: INT

Integer that specifies the index of the array element that is used as the first point of the cardinal spline.

[in] numberOfSegments

Type: INT

Integer that specifies the number of segments in the cardinal spline. Segments are the curves that connect consecutive points in the array.

[in] tension

Type: REAL

Nonnegative real number that controls the length of the curve and how the curve bends. A value of 0 specifies that the spline is a sequence of straight line segments. As the value increases, the curve becomes fuller.

Return value

Type: Status

If the method succeeds, it returns Ok, which is an element of the Status enumeration.

If the method fails, it returns one of the other elements of the Status enumeration.


You should keep a copy of the points array if those points will be needed later. The GraphicsPath object does not store the points passed to the AddClosedCurve method; instead, it converts the cardinal spline to a sequence of Bézier splines and stores the points that define those Bézier splines. You cannot retrieve the original array of points from the GraphicsPath object.


The following example creates a GraphicsPath object path, adds a cardinal spline to path, and then draws path. The spline is built from the points indexed 2 through 6 in an array of eight points.

VOID AddCurveExample2(HDC hdc)
   GraphicsPath   path;
   Graphics graphics(hdc);
   Point pts[] = {Point(50, 50),
                  Point(70, 80),
                  Point(100, 100),
                  Point(130, 40),
                  Point(150, 90),
                  Point(180, 30),
                  Point(210, 120),
                  Point(240, 80)};
      8,     // There are eight points in the array. 
      2,     // Start at the point with index 2.
      4,     // Four segments. End at the point with index 6.
   Pen pen(Color(255, 0, 0, 255));
   graphics.DrawPath(&pen, &path);
   // Draw all eight points in the array.
   SolidBrush brush(Color(255, 255, 0, 0));
   for(INT j = 0; j <= 7; ++j)
      graphics.FillEllipse(&brush, pts[j].X - 3, pts[j].Y - 3, 6, 6);


Minimum supported client Windows XP, Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header gdipluspath.h (include Gdiplus.h)
Library Gdiplus.lib
DLL Gdiplus.dll

See also

AddBezier Methods

AddBeziers Methods

AddClosedCurve Methods

AddCurve Methods

Cardinal Splines

Clipping with a Region

Constructing and Drawing Paths

Creating a Path Gradient

Drawing Cardinal Splines