Detecting insertion/removal of USB input devices on Windows 10
There are multiple ways to detect what is happening with device changes
Detecting USB Insertion / Removal Events in Windows using C++
One suggested way is to use WM_DEVICECHANGE message. https://stackoverflow.com/a/4078996/2830850
One such example an be found at below
#Modified from: http://wiki.wxpython.org/HookingTheWndProc
##########################################################################
##
## This is a modification of the original WndProcHookMixin by Kevin Moore,
## modified to use ctypes only instead of pywin32, so it can be used
## with no additional dependencies in Python 2.5
##
##########################################################################
import sys
import ctypes
#import GUID
from ctypes import c_long, c_int, wintypes
import wx
GWL_WNDPROC = -4
WM_DESTROY = 2
DBT_DEVTYP_DEVICEINTERFACE = 0x00000005 # device interface class
DBT_DEVICEREMOVECOMPLETE = 0x8004 # device is gone
DBT_DEVICEARRIVAL = 0x8000 # system detected a new device
WM_DEVICECHANGE = 0x0219
class GUID(ctypes.Structure):
_pack_ = 1
_fields_ = [("Data1", ctypes.c_ulong),
("Data2", ctypes.c_ushort),
("Data3", ctypes.c_ushort),
("Data4", ctypes.c_ubyte * 8)]
## It's probably not neccesary to make this distinction, but it never hurts to be safe
if 'unicode' in wx.PlatformInfo:
SetWindowLong = ctypes.windll.user32.SetWindowLongW
CallWindowProc = ctypes.windll.user32.CallWindowProcW
else:
SetWindowLong = ctypes.windll.user32.SetWindowLongA
CallWindowProc = ctypes.windll.user32.CallWindowProcA
## Create a type that will be used to cast a python callable to a c callback function
## first arg is return type, the rest are the arguments
#WndProcType = ctypes.WINFUNCTYPE(c_int, wintypes.HWND, wintypes.UINT, wintypes.WPARAM, wintypes.LPARAM)
WndProcType = ctypes.WINFUNCTYPE(ctypes.c_long, ctypes.c_int, ctypes.c_uint, ctypes.c_int, ctypes.c_int)
if 'unicode' in wx.PlatformInfo:
RegisterDeviceNotification = ctypes.windll.user32.RegisterDeviceNotificationW
else:
RegisterDeviceNotification = ctypes.windll.user32.RegisterDeviceNotificationA
RegisterDeviceNotification.restype = wintypes.HANDLE
RegisterDeviceNotification.argtypes = [wintypes.HANDLE, wintypes.c_void_p, wintypes.DWORD]
UnregisterDeviceNotification = ctypes.windll.user32.UnregisterDeviceNotification
UnregisterDeviceNotification.restype = wintypes.BOOL
UnregisterDeviceNotification.argtypes = [wintypes.HANDLE]
class DEV_BROADCAST_DEVICEINTERFACE(ctypes.Structure):
_fields_ = [("dbcc_size", ctypes.c_ulong),
("dbcc_devicetype", ctypes.c_ulong),
("dbcc_reserved", ctypes.c_ulong),
("dbcc_classguid", GUID),
("dbcc_name", ctypes.c_wchar * 256)]
class DEV_BROADCAST_HDR(ctypes.Structure):
_fields_ = [("dbch_size", wintypes.DWORD),
("dbch_devicetype", wintypes.DWORD),
("dbch_reserved", wintypes.DWORD)]
GUID_DEVCLASS_PORTS = GUID(0x4D36E978, 0xE325, 0x11CE,
(ctypes.c_ubyte*8)(0xBF, 0xC1, 0x08, 0x00, 0x2B, 0xE1, 0x03, 0x18))
GUID_DEVINTERFACE_USB_DEVICE = GUID(0xA5DCBF10L, 0x6530,0x11D2,
(ctypes.c_ubyte*8)(0x90, 0x1F, 0x00,0xC0, 0x4F, 0xB9, 0x51, 0xED))
class WndProcHookMixin:
"""
This class can be mixed in with any wxWindows window class in order to hook it's WndProc function.
You supply a set of message handler functions with the function addMsgHandler. When the window receives that
message, the specified handler function is invoked. If the handler explicitly returns False then the standard
WindowProc will not be invoked with the message. You can really screw things up this way, so be careful.
This is not the correct way to deal with standard windows messages in wxPython (i.e. button click, paint, etc)
use the standard wxWindows method of binding events for that. This is really for capturing custom windows messages
or windows messages that are outside of the wxWindows world.
"""
def __init__(self):
self.__msgDict = {}
## We need to maintain a reference to the WndProcType wrapper
## because ctypes doesn't
self.__localWndProcWrapped = None
self.rtnHandles = []
def hookWndProc(self):
self.__localWndProcWrapped = WndProcType(self.localWndProc)
self.__oldWndProc = SetWindowLong(self.GetHandle(), GWL_WNDPROC, self.__localWndProcWrapped)
def unhookWndProc(self):
SetWindowLong(self.GetHandle(), GWL_WNDPROC, self.__oldWndProc)
## Allow the ctypes wrapper to be garbage collected
self.__localWndProcWrapped = None
def addMsgHandler(self,messageNumber,handler):
self.__msgDict[messageNumber] = handler
def localWndProc(self, hWnd, msg, wParam, lParam):
# call the handler if one exists
# performance note: "in" is the fastest way to check for a key
# when the key is unlikely to be found
# (which is the case here, since most messages will not have handlers).
# This is called via a ctypes shim for every single windows message
# so dispatch speed is important
if msg in self.__msgDict:
# if the handler returns false, we terminate the message here
# Note that we don't pass the hwnd or the message along
# Handlers should be really, really careful about returning false here
if self.__msgDict[msg](wParam,lParam) == False:
return
# Restore the old WndProc on Destroy.
if msg == WM_DESTROY: self.unhookWndProc()
return CallWindowProc(self.__oldWndProc, hWnd, msg, wParam, lParam)
def registerDeviceNotification(self, guid, devicetype=DBT_DEVTYP_DEVICEINTERFACE):
devIF = DEV_BROADCAST_DEVICEINTERFACE()
devIF.dbcc_size = ctypes.sizeof(DEV_BROADCAST_DEVICEINTERFACE)
devIF.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE
if guid:
devIF.dbcc_classguid = GUID.GUID(guid)
return RegisterDeviceNotification(self.GetHandle(), ctypes.byref(devIF), 0)
def unregisterDeviceNotification(self, handle):
if UnregisterDeviceNotification(handle) == 0:
raise Exception("Unable to unregister device notification messages")
# a simple example
if __name__ == "__main__":
class MyFrame(wx.Frame,WndProcHookMixin):
def __init__(self,parent):
WndProcHookMixin.__init__(self)
wx.Frame.__init__(self,parent,-1,"Insert and Remove USE Device and Watch STDOUT",size=(640,480))
self.Bind(wx.EVT_CLOSE, self.onClose)
#Change the following guid to the GUID of the device you want notifications for
#self.devNotifyHandle = self.registerDeviceNotification(guid="{3c5e1462-5695-4e18-876b-f3f3d08aaf18}")
dbh = DEV_BROADCAST_DEVICEINTERFACE()
dbh.dbcc_size = ctypes.sizeof(DEV_BROADCAST_DEVICEINTERFACE)
dbh.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE
dbh.dbcc_classguid = GUID_DEVINTERFACE_USB_DEVICE
self.devNotifyHandle = RegisterDeviceNotification(self.GetHandle(), ctypes.byref(dbh), 0)
self.addMsgHandler(WM_DEVICECHANGE, self.onDeviceChange)
self.hookWndProc()
def onDeviceChange(self,wParam,lParam):
print "WM_DEVICECHANGE [WPARAM:%i][LPARAM:%i]"%(wParam,lParam)
if wParam == DBT_DEVICEARRIVAL:
print "Device Arrival"
elif wParam == DBT_DEVICEREMOVECOMPLETE:
print "Device Remvoed"
if lParam:
dbh = DEV_BROADCAST_HDR.from_address(lParam)
if dbh.dbch_devicetype == DBT_DEVTYP_DEVICEINTERFACE:
dbd = DEV_BROADCAST_DEVICEINTERFACE.from_address(lParam)
#Verify that the USB VID and PID match our assigned VID and PID
if 'Vid_10c4&Pid_8382' in dbd.dbcc_name:
print "Was Our USB Device"
return True
def onClose(self, event):
self.unregisterDeviceNotification(self.devNotifyHandle)
event.Skip()
app = wx.App(False)
frame = MyFrame(None)
frame.Show()
app.MainLoop()
Above is taken from https://github.com/weiwei22844/UsefullPython/blob/fa8603b92cb0b3f6ce00c876f24138211f47e906/HookUsbMsg.py
Now coming back to your code
import wmi
device_connected_wql = "SELECT * FROM __InstanceCreationEvent WITHIN 2 WHERE TargetInstance ISA \'Win32_Keyboard\'"
device_disconnected_wql = "SELECT * FROM __InstanceDeletionEvent WITHIN 2 WHERE TargetInstance ISA \'Win32_Keyboard\'"
c = wmi.WMI()
connected_watcher = c.watch_for(raw_wql=device_connected_wql)
disconnected_watcher = c.watch_for(raw_wql=device_disconnected_wql)
while 1:
connected = connected_watcher()
disconnected = disconnected_watcher()
if connected:
print("Keyboard connected")
if disconnected:
print("Keyboard disconnected")
The way you call is connected_watcher and disconnected_watcher in series, both are blocking call. So when you call it first connected becomes true and then the disconnected_watcher gets called which blocked until a device is disconnected. That is why when you disconnected, you see both the messages together.
The way you can fix it is by making sure you time out these queries
while 1:
try:
connected = connected_watcher(timeout_ms=10)
except wmi.x_wmi_timed_out:
pass
else:
if connected:
print("Keyboard connected")
try:
disconnected = disconnected_watcher(timeout_ms=10)
except wmi.x_wmi_timed_out:
pass
else:
if disconnected:
print("Keyboard disconnected")
Another approach is to use threads. But to make your code thread compatible you need to make it like below
class VolumeRemovalWatcher:
def __init__(self, callback=None):
self.stop_wanted=False
self.callback=callback
def stop(self):
self.stop_wanted = True
def watch_for_events(self):
if not threading.current_thread() is threading.main_thread():
pythoncom.CoInitialize()
try:
w = WMI()
watcher = w.Win32_VolumeChangeEvent.watch_for(EventType=3)
while not self.stop_wanted:
try:
event = watcher(timeout_ms=1000)
except x_wmi_timed_out:
pass
else:
print(event.DriveName)
if self.callback is not None:
self.callback(event.DriveName)
except Exception as e:
print(e)
return None
finally:
if not threading.current_thread() is threading.main_thread():
pythoncom.CoUninitialize()
Credits for above code to https://github.com/utytlanyjoe/pyWmiHandler/blob/89b934301990a4a955ec13db21caaf81d9a94f63/wmi_wrapper.py