SetOverlayOffsetFunc

BOOLEAN
SetOverlayOffsetFunc(
PDEVICE_INFO pDevInfo,
PRECT prc
);

The SetOverlayOffsetFunc function sets the overlay offset rectangle. This rectangle defines which portion of the frame buffer appears in the overlay window. The function is provided by the kernel-mode driver, and the SetOverlayOffsetFunc name is a placeholder for a driver-specified function name.

Parameters

pDevInfo: Pointer to the DEVICE_INFO structure returned by VC_Init.
prc: Pointer to a RECT structure containing screen coordinates that describe the offset rectangle. (The RECT structure is described in the Win32 SDK.)

Return Value

Returns TRUE if the operation succeeds. Otherwise returns FALSE. If FALSE, VCKernel.lib sets the Win32 error code value to STATUS_DEVICE_CONFIGURATION_ERROR.

Comments

The VCKernel.lib library calls a kernel-mode driver’s SetOverlayOffsetFunc function when the driver receives an IOCTL_VIDC_OVERLAY_OFFSET control code. User-mode drivers using VCUser.lib send this control code by calling VC_SetOverlayOffset.

For more information about implementing the offset rectangle, see VC_SetOverlayOffset.

Support for a SetOverlayOffsetFunc function is required, if the device supports overlay and panning of the source image. If a driver does support the function, it must place its address in the VC_CALLBACK structure supplied by VCKernel.lib. If a driver that does not support a SetOverlayOffsetFunc function receives an IOCTL_VIDC_OVERLAY_OFFSET control code, VCKernel.lib sets the Win32 error code value to STATUS_INVALID_DEVICE_REQUEST.