LPDD_NOTIFYCALLBACK callback function (ddkmapi.h)
The NotifyCallback callback function performs operations related to an event that occurred.
Syntax
LPDD_NOTIFYCALLBACK LpddNotifycallback;
ULONG LpddNotifycallback(
DWORD dwFlags,
PVOID pContext,
DWORD dwParam1,
DWORD dwParam2
)
{...}
Parameters
dwFlags
Indicates the event that caused the callback to be called. The values in dwParam1 and dwParam2 depend on the value of dwFlags. The following values are possible:
| Flag | dwParam1 | dwParam2 |
|---|---|---|
| DDNOTIFY_CLOSECAPTURE | hCapture | unused |
| DDNOTIFY_CLOSEDIRECTDRAW | hDirectDraw | unused |
| DDNOTIFY_CLOSESURFACE | hSurface | unused |
| DDNOTIFY_CLOSEVIDEOPORT | hVideoPort | unused |
| DDNOTIFY_DISPLAY_VSYNC | hDirectDraw | unused |
| DDNOTIFY_POSTDOSBOX | hDirectDraw | unused |
| DDNOTIFY_POSTRESCHANGE | hDirectDraw | unused |
| DDNOTIFY_PREDOSBOX | hDirectDraw | unused |
| DDNOTIFY_PRERESCHANGE | hDirectDraw | unused |
| DDNOTIFY_VP_LINE | hVideoPort | unused |
| DDNOTIFY_VP_VSYNC | hVideoPort | unused |
pContext
Contains a value that the caller passed in a call to the DxApi function along with a specific function identifier. For more information about function identifiers, see DxApi.
dwParam1
Handle to the object related to the event that caused the callback to be called.
dwParam2
Unused.
Return value
NotifyCallback returns zero.
Remarks
A video capture driver supplies a NotifyCallback callback function to the DirectDraw runtime when the video capture driver calls the runtime's DxApi function. For more information, see Notify Callback Functions in a Video Capture Driver.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | ddkmapi.h (include Ddkmapi.h) |