CreateRoundRectRgn info Overview Group

The CreateRoundRectRgn function creates a rectangular region with rounded corners.

HRGN CreateRoundRectRgn(

int nLeftRect,	// x-coordinate of the region’s upper-left corner
int nTopRect,	// y-coordinate of the region’s upper-left corner
int nRightRect,	// x-coordinate of the region’s lower-right corner
int nBottomRect,	// y-coordinate of the region’s lower-right corner
int nWidthEllipse,	// height of ellipse for rounded corners
int nHeightEllipse	// width of ellipse for rounded corners
);

Parameters

nLeftRect: Specifies the x-coordinate of the upper-left corner of the region.
nTopRect: Specifies the y-coordinate of the upper-left corner of the region.
nRightRect: Specifies the x-coordinate of the lower-right corner of the region.
nBottomRect: Specifies the y-coordinate of the lower-right corner of the region.
nWidthEllipse: Specifies the width of the ellipse used to create the rounded corners.
nHeightEllipse: Specifies the height of the ellipse used to create the rounded corners.

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

If the function fails, the return value is NULL. To get extended error information, call GetLastError.