CreateRectRgn function (wingdi.h)

Article
02/22/2024

The CreateRectRgn function creates a rectangular region.

Syntax

HRGN CreateRectRgn(
  [in] int x1,
  [in] int y1,
  [in] int x2,
  [in] int y2
);

Parameters

[in] x1

Specifies the x-coordinate of the upper-left corner of the region in logical units.

[in] y1

Specifies the y-coordinate of the upper-left corner of the region in logical units.

[in] x2

Specifies the x-coordinate of the lower-right corner of the region in logical units.

[in] y2

Specifies the y-coordinate of the lower-right corner of the region in logical units.

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.

Examples

For an example, see Drawing Markers.

Requirements

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