PolyDraw function (wingdi.h)

The PolyDraw function draws a set of line segments and Bézier curves.


BOOL PolyDraw(
  [in] HDC         hdc,
  [in] const POINT *apt,
  [in] const BYTE  *aj,
  [in] int         cpt


[in] hdc

A handle to a device context.

[in] apt

A pointer to an array of POINT structures that contains the endpoints for each line segment and the endpoints and control points for each Bézier curve, in logical units.

[in] aj

A pointer to an array that specifies how each point in the lppt array is used. This parameter can be one of the following values.

Type Meaning
Specifies that this point starts a disjoint figure. This point becomes the new current position.
Specifies that a line is to be drawn from the current position to this point, which then becomes the new current position.
Specifies that this point is a control point or ending point for a Bézier curve.

PT_BEZIERTO types always occur in sets of three. The current position defines the starting point for the Bézier curve. The first two PT_BEZIERTO points are the control points, and the third PT_BEZIERTO point is the ending point. The ending point becomes the new current position. If there are not three consecutive PT_BEZIERTO points, an error results.


A PT_LINETO or PT_BEZIERTO type can be combined with the following value by using the bitwise operator OR to indicate that the corresponding point is the last point in a figure and the figure is closed.

Value Meaning
Specifies that the figure is automatically closed after the PT_LINETO or PT_BEZIERTO type for this point is done. A line is drawn from this point to the most recent PT_MOVETO or MoveToEx point.

This value is combined with the PT_LINETO type for a line, or with the PT_BEZIERTO type of the ending point for a Bézier curve, by using the bitwise operator OR.

The current position is set to the ending point of the closing line.

[in] cpt

The total number of points in the lppt array, the same as the number of bytes in the lpbTypes array.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.


The PolyDraw function can be used in place of consecutive calls to MoveToEx, LineTo, and PolyBezierTo functions to draw disjoint figures. The lines and curves are drawn using the current pen and figures are not filled. If there is an active path started by calling BeginPath, PolyDraw adds to the path.

The points contained in the lppt array and in the lpbTypes array indicate whether each point is part of a MoveTo, LineTo, or PolyBezierTo operation. It is also possible to close figures.

This function updates the current position.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header wingdi.h (include Windows.h)
Library Gdi32.lib
DLL Gdi32.dll

See also



Line and Curve Functions


Lines and Curves Overview