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CreatePolygonRgn function

The CreatePolygonRgn function creates a polygonal region.

Syntax


HRGN CreatePolygonRgn(
  _In_  const POINT *lppt,
  _In_  int cPoints,
  _In_  int fnPolyFillMode
);

Parameters

lppt [in]

A pointer to an array of POINT structures that define the vertices of the polygon in logical units. The polygon is presumed closed. Each vertex can be specified only once.

cPoints [in]

The number of points in the array.

fnPolyFillMode [in]

The fill mode used to determine which pixels are in the region. This parameter can be one of the following values.

ValueMeaning
ALTERNATE

Selects alternate mode (fills area between odd-numbered and even-numbered polygon sides on each scan line).

WINDING

Selects winding mode (fills any region with a nonzero winding value).

 

For more information about these modes, see the SetPolyFillMode function.

Return value

If the function succeeds, the return value is the handle to the region.

If the function fails, the return value is NULL.

Remarks

When you no longer need the HRGN object, call the DeleteObject function to delete it.

Region coordinates are represented as 27-bit signed integers.

Regions created by the Create<shape>Rgn methods (such as CreateRectRgn and CreatePolygonRgn) only include the interior of the shape; the shape's outline is excluded from the region. This means that any point on a line between two sequential vertices is not included in the region. If you were to call PtInRegion for such a point, it would return zero as the result.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Wingdi.h (include Windows.h)

Library

Gdi32.lib

DLL

Gdi32.dll

See also

Regions Overview
Region Functions
CreatePolyPolygonRgn
CreateRectRgn
CreateRectRgnIndirect
CreateRoundRectRgn
ExtCreateRegion
GetRegionData
DeleteObject
POINT
SelectObject
SetPolyFillMode

 

 

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