/// <summary>
/// Finds a device given its PID and VID
/// </summary>
/// <param name="nVid">Vendor id for device (VID)</param>
/// <param name="nPid">Product id for device (PID)</param>
/// <returns>A new device class of the given type or null</returns>
public static HIDDevice FindDevice(int nVid, int nPid)
{
string strPath = string.Empty;
string strSearch = string.Format("vid_{0:x4}&pid_{1:x4}", nVid, nPid); // first, build the path search string
Guid gHid;
HidD_GetHidGuid(out gHid); // next, get the GUID from Windows that it uses to represent the HID USB interface
IntPtr 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
{
DeviceInterfaceData 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
int 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!
{
HIDDevice oNewDevice = new HIDDevice(); // create an instance of the class for this device
oNewDevice.Initialise(strDevicePath); // initialise it with the device path
return oNewDevice; // and return it
}
nIndex++; // if we get here, we didn't find our device. So move on to the next one.
}
}
finally
{
// Before we go, we have to free up the InfoSet memory reserved by SetupDiGetClassDevs
SetupDiDestroyDeviceInfoList(hInfoSet);
}
return null; // oops, didn't find our device
}
/// <summary>
/// Construction. Setup the buffer with the correct output report length dictated by the device
/// </summary>
/// <param name="oDev">Creating device</param>
public HIDOutputReport(HIDDevice oDev)
: base(oDev)
{
SetBuffer(new byte[oDev.OutputReportLength]);
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="oDev">Constructing device</param>
public HIDReport(HIDDevice oDev)
{
// Do nothing
}
/// <summary>
/// Construction. Do nothing
/// </summary>
/// <param name="oDev">Creating device</param>
public HIDInputReport(HIDDevice oDev)
: base(oDev)
{
}