PFNUSBCAMD_WaitOnDeviceEvent callback function (usbcamdi.h)
The USBCAMD_WaitOnDeviceEvent service is used to perform a read from the interrupt pipe if the camera has an interrupt pipe for external event notifications.
Syntax
PFNUSBCAMD_WaitOnDeviceEvent PfnusbcamdWaitondeviceevent;
NTSTATUS PfnusbcamdWaitondeviceevent(
[in] PVOID DeviceContext,
[in] ULONG PipeIndex,
[in] PVOID Buffer,
[in] ULONG BufferLength,
[in] PCOMMAND_COMPLETE_FUNCTION EventComplete,
[in] PVOID EventContext,
[in] BOOLEAN LoopBack
)
{...}
Parameters
[in] DeviceContext
A pointer to device-specific context.
[in] PipeIndex
Specifies the index of the interrupt pipe.
[in] Buffer
A pointer to the read buffer.
[in] BufferLength
Length of the read buffer, in bytes.
[in] EventComplete
Pointer to a camera minidriver defined CommandCompleteFunction, which is called when the interrupt read is completed This value can be NULL.
[in] EventContext
Pointer to a block of memory, that is passed as an argument to the camera minidriver defined CommandCompleteFunction.
[in] LoopBack
Specifies if USBCAMD is to resubmit another read request to the interrupt pipe every time an interrupt read is completed. Set to TRUE
Return value
USBCAMD_WaitOnDeviceEvent returns STATUS_SUCCESS if the call was successful. Other possible error codes include:
| Return code | Description |
|---|---|
| STATUS_FILE_CLOSED | The device has been removed. |
| STATUS_INVALID_PARAMETER | USBCAMD may return STATUS_INVALID_PARAMETER for a number of reasons, including: The value passed in the PipeIndex argument is invalid, the type of the pipe specified by the PipeIndex argument represents an invalid type of pipe, a bulk read/write request already exists, or the Buffer argument is NULL. The length specified in the BufferLength argument is smaller than the maximum packet size. |
| STATUS_PENDING | The event work item is deferred. |
| STATUS_INSUFFICIENT_RESOURCES | There are insufficient resources to allocate a work item to read from the pipe. |
Remarks
The typical usage scenario for this function is a camera with a snapshot button and an interrupt pipe associated with the button. When a user presses the snapshot button, the read request on the interrupt pipe is satisfied and the camera minidriver is called back. If the camera minidriver sets USBCAMD_CamControlFlag_EnableDeviceEvents in the CamControlFlag argument during the USBCAMD_InitializeNewInterface call, the STI monitor also is notified of the snapshot event.
USBCAMD_WaitOnDeviceEvent is not available in USBCAMD version 1.0.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | usbcamdi.h (include Usbcamdi.h) |