DWORD
GetOverlayModeFunc(
PDEVICE_INFO pDevInfo
);
The GetOverlayModeFunc function returns the device’s overlay capabilities. The function is provided by the kernel-mode driver, and the GetOverlayModeFunc name is a placeholder for a driver-specified function name.
Parameters
pDevInfo
Pointer to the DEVICE_INFO structure returned by VC_Init.
Return Value
Returns a DWORD value containing flags. The following flags are defined.
| Flag | Definition |
| VCO_KEYCOLOUR | Indicates the device supports a key color. |
| VCO_KEYCOLOUR_FIXED | Indicates the key color cannot be modified. |
| VCO_KEYCOLOUR_RGB | If set, indicates the key color must be specified as an RGB color. If clear, indicates the key color must be specified as a palette index number. |
| VCO_SIMPLE_RECT | Indicates the device supports a single rectangular overlay region. |
| VCO_COMPLEX_REGION | Indicates the device supports a complex (multi-rectangle) overlay region. |
| VCO_CAN_DRAW_Y411 | Indicates the device can display bitmaps that contain YUV 4:1:1-formatted data. |
| VCO_CAN_DRAW_S422 | Indicates the device can display bitmaps that contain YUV 4:2:2-formatted data. |
Comments
The VCKernel.lib library calls a kernel-mode driver’s GetOverlayModeFunc function when the driver receives an IOCTL_VIDC_OVERLAY_MODE control code. User-mode drivers using VCUser.lib send this control code by calling VC_GetOverlayMode.
The driver sets the appropriate flags in the return value, based on the hardware’s capabilities.
Support for a GetOverlayModeFunc function is required. The driver must place the function’s address in the VC_CALLBACK structure supplied by VCKernel.lib.