wglDescribeLayerPlane

The wglDescribeLayerPlane function obtains information about the layer planes of a given pixel format.

BOOL wglDescribeLayerPlane(
  HDC  hdc,          // device context whose layer planes are of 
                     // interest
  int  iPixelFormat, // pixel format of the desired layer plane
  int  iLayerPlane,  // specifies an overlay or underlay plane
  UINT  nBytes,      // specifies the size, in bytes, of a 
                     // LAYERPLANEDESCRIPTOR structure
  LPLAYERPLANEDESCRIPTOR plpd 
                     // points to a LAYERPLANEDESCRIPTOR structure
);

Parameters

hdc

Specifies the device context of a window whose layer planes are to be described.

iPixelFormat

Specifies which layer planes of a pixel format are being described.

iLayerPlane

Specifies the overlay or underlay plane. Positive values of iLayerPlane identify overlay planes, where 1 is the first overlay plane over the main plane, 2 is the second overlay plane over the first overlay plane, and so on. Negative values identify underlay planes, where –1 is the first underlay plane under the main plane, –2 is the second underlay plane under the first underlay plane, and so on. The number of overlay and underlay planes is given in the bReserved member of the PIXELFORMATDESCRIPTOR structure.

nBytes

Specifies the size, in bytes, of the structure pointed to by plpd. The wglDescribeLayerPlane function stores layer plane data in a LAYERPLANEDESCRIPTOR structure, and stores no more than nBytes of data. Set the value of nBytes to the size of LAYERPLANEDESCRIPTOR.

plpd

Points to a LAYERPLANEDESCRIPTOR structure. The wglDescribeLayerPlane function sets the value of the structure's data members. The function stores the number of bytes of data copied to the structure in the nSize member.

Return Values

If the function succeeds, the return value is TRUE. In addition, the wglDescribeLayerPlane function sets the members of the LAYERPLANEDESCRIPTOR structure pointed to by plpd according to the specified layer plane (iLayerPlane) of the specified pixel format (iPixelFormat).

If the function fails, the return value is FALSE.

Remarks

The numbering of planes (iLayerPlane) determines their order. Higher-numbered planes overlay lower-numbered planes.

Requirements

  Windows NT/2000: Requires Windows NT 3.5 or later.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in wingdi.h.
  Import Library: Use opengl32.lib.

See Also

OpenGL on Windows NT, Windows 2000, and Windows 95/98, WGL Functions, DescribePixelFormat, LAYERPLANEDESCRIPTOR, PIXELFORMATDESCRIPTOR, wglCreateLayerContext