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#include <pch.h>
/*
** Driver TODO: Add code to EvtDeviceOwnershipChange to reset the device state to a default.
**
** PosCx calls this callback to signal that the ownership of the device has transitioned from one file handle
** to another. When this happens, app developers expect that the settings for the device are restored to a
** "default" state, so the driver should do what is necessary to satisfy that expectation here.
**
*/
VOID EvtDeviceOwnershipChange(_In_ WDFDEVICE Device, _In_opt_ WDFFILEOBJECT OldOwnerFileObj, _In_opt_ WDFFILEOBJECT NewOwnerFileObj)
{
UNREFERENCED_PARAMETER(Device);
UNREFERENCED_PARAMETER(OldOwnerFileObj);
UNREFERENCED_PARAMETER(NewOwnerFileObj);
// This function signals that ownership has transitioned from one file handle to another (typically from one app to another).
// As a result, the driver is expected to reset all settings to a default state.
}
/*
** Driver TODO:
**
** This part of the sample demonstrates how the driver will return data to the runtime. How this method would be called depends
** on the driver implementation.
*/
VOID EvtOnBarcodeScanDataRetrieved(_In_ WDFDEVICE Device)
{
// Events that the runtime can handle for a barcode scanner device are:
// PosEventType::BarcodeScannerDataReceived -- the standard event with barcode scan data
// PosEventType::BarcodeScannerErrorOccurred -- an event that should be sent if an error occured while scanning data
// PosEventType::BarcodeScannerImagePreviewReceived -- an event that sends a complete .bmp image to the runtime for imagers
// PosEventType::BarcodeScannerTriggerPressed -- an event indicating that the trigger on the device has been pushed and the device is looking for data
// PosEventType::BarcodeScannerTriggerReleased -- an event indicating that the trigger on the device has been released and the device is no longer looking for data
// PosEventType::StatusUpdated -- an event to indicate changes to power state
//
// Additionally, the following event is sent to the runtime, but is handled entirely by PosCx
// PosEventType::ReleaseDeviceRequested
// The following shows an example of sending barcode scan data
CHAR exampleData[] = "]0A12345";
CHAR exampleDataLabel[] = "12345";
// total size is the struct plus the size of the two strings (minus the null terminators which aren't transmitted).
size_t totalSize = sizeof(PosBarcodeScannerDataReceivedEventData) + sizeof(exampleData) - sizeof(CHAR) + sizeof(exampleDataLabel) - sizeof(CHAR);
// PosCx supports two methods of pending the event data -- one where it takes the WDFMEMORY for the event, and the other where it creates it
// The subtle difference between the two is that the one that takes the WDFMEMORY must have the event header information already added.
//
// Since that's the case with the PosBarcodeScannerDataReceivedEventData data structure, barcode scanner drivers should create the WDFMEMORY objects
// and pass them to PosCx.
WDF_OBJECT_ATTRIBUTES Attributes;
WDF_OBJECT_ATTRIBUTES_INIT(&Attributes);
Attributes.ParentObject = Device;
BYTE* eventData = nullptr;
WDFMEMORY eventMemory = NULL;
NTSTATUS status = WdfMemoryCreate(
&Attributes,
NonPagedPoolNx,
(ULONG)'eSOP',
totalSize,
&eventMemory,
(PVOID*)&eventData
);
if (!NT_SUCCESS(status))
{
// handle out of memory error
return;
}
// Calculate data and label sizes
size_t exampleDataByteCount = sizeof(exampleData) - sizeof(CHAR);
size_t exampleLabelByteCount = sizeof(exampleDataLabel) - sizeof(CHAR);
PosBarcodeScannerDataReceivedEventData* eventHeader = (PosBarcodeScannerDataReceivedEventData*)eventData;
eventHeader->Header.EventType = PosEventType::BarcodeScannerDataReceived;
eventHeader->Header.DataLength = (UINT32)totalSize;
eventHeader->DataType = BarcodeSymbology::Ean13;
eventHeader->ScanDataLength = (UINT32)exampleDataByteCount;
eventHeader->ScanDataLabelLength = (UINT32)exampleLabelByteCount;
// These use memcpy because wcscpy would append the null terminator and the event data doesn't use it
BYTE* eventScanData = eventData + sizeof(PosBarcodeScannerDataReceivedEventData);
memcpy(eventScanData, exampleData, exampleDataByteCount);
BYTE* eventLabelData = eventScanData + exampleDataByteCount;
memcpy(eventLabelData, exampleDataLabel, exampleLabelByteCount);
// This call actually pends the data to be send to the WinRT APIs.
status = PosCxPutPendingEventMemory(Device, SCANNER_INTERFACE_TAG, eventMemory, POS_CX_EVENT_ATTR_DATA);
if (!NT_SUCCESS(status))
{
// This should only happen in rare cases such as out of memory (or that the device or interface tag isn't found). The driver should most likely drop the event.
WdfObjectDelete(eventMemory);
}
}
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