/// <summary>
/// Initialises the device. This must be called before events start triggering. If device is allready initialized does nothing.
/// </summary>
/// <exception cref="HIDDeviceException">Is thrown if something unexpected happend during initialization</exception>
/// <exception cref="DeviceAllreadyInUseException">Is thrown if device is allready in use somewhere else.</exception>
public virtual void EnsureIsInitialized()
{
if (IsInitialized)
{
return;
}
// Create the file from the device path
handle = CreateFile(DevicePath, GENERIC_READ | GENERIC_WRITE, 0, IntPtr.Zero, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, IntPtr.Zero);
if (handle != InvalidHandleValue) // if the open worked...
{
IntPtr lpData;
if (HidD_GetPreparsedData(handle, out lpData)) // get windows to read the device data into an internal buffer
{
try
{
HidCaps oCaps;
HidP_GetCaps(lpData, out oCaps); // extract the device capabilities from the internal buffer
inputReportLength = oCaps.InputReportByteLength; // get the input...
outputReportLength = oCaps.OutputReportByteLength; // ... and output report lengths
file = new FileStream(new SafeFileHandle(handle, false), FileAccess.Read | FileAccess.Write, inputReportLength, true);
IsInitialized = true;
BeginAsyncRead(); // kick off the first asynchronous read
}
catch (Exception)
{
throw HIDDeviceException.GenerateWithWinError("Failed to get the detailed data from the hid.");
}
finally
{
HidD_FreePreparsedData(ref lpData); // before we quit the funtion, we must free the internal buffer reserved in GetPreparsedData
}
}
else // GetPreparsedData failed? Chuck an exception
{
throw HIDDeviceException.GenerateWithWinError("GetPreparsedData failed");
}
}
else // File open failed? Chuck an exception
{
handle = IntPtr.Zero;
throw new DeviceAllreadyInUseException("Device you tried to initilized is allready in use.");
}
}
/// <summary>
/// Finds devices of type.
/// </summary>
/// <typeparam name="TDevice">Type of device to look for.</typeparam>
/// <returns>Enumeration of devices.</returns>
public static IEnumerable <DeviceDescription <TDevice> > FindDevices <TDevice>() where TDevice : HIDDevice
{
var devices = new List <DeviceDescription <TDevice> >();
//Creating instance to get Vendor and product id's.
var instance = (TDevice)Activator.CreateInstance(typeof(TDevice), new[] { "" });
var strSearch = string.Format("vid_{0:x4}&pid_{1:x4}", instance.VendorId, instance.ProductId); // first, build the path search string
var gHid = HIDGuid;
//HidD_GetHidGuid(out gHid); // next, get the GUID from Windows that it uses to represent the HID USB interface
var hInfoSet = SetupDiGetClassDevs(ref gHid, null, IntPtr.Zero, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT); // this gets a list of all HID devices currently connected to the computer (InfoSet)
try
{
var oInterface = new DeviceInterfaceData(); // build up a device interface data block
oInterface.Size = Marshal.SizeOf(oInterface);
// Now iterate through the InfoSet memory block assigned within Windows in the call to SetupDiGetClassDevs
// to get device details for each device connected
var nIndex = 0;
while (SetupDiEnumDeviceInterfaces(hInfoSet, 0, ref gHid, (uint)nIndex, ref oInterface)) // this gets the device interface information for a device at index 'nIndex' in the memory block
{
string strDevicePath = GetDevicePath(hInfoSet, ref oInterface); // get the device path (see helper method 'GetDevicePath')
if (strDevicePath.IndexOf(strSearch) >= 0) // do a string search, if we find the VID/PID string then we found our device!
{
// Creating instance and adding device path as constructor parameter.
var oNewDevice = (DeviceDescription <TDevice>)Activator.CreateInstance(typeof(DeviceDescription <TDevice>), new[] { strDevicePath });
devices.Add(oNewDevice);
}
nIndex++; // if we get here, we didn't find our device. So move on to the next one.
}
}
catch (Exception ex)
{
throw HIDDeviceException.GenerateError(ex.ToString());
}
finally
{
// Before we go, we have to free up the InfoSet memory reserved by SetupDiGetClassDevs
SetupDiDestroyDeviceInfoList(hInfoSet);
}
return(devices);
}
