Detect when system is idle (Python recipe) by Gabriel Genellina

ActiveState Code (http://code.activestate.com/recipes/576786/)

"""
Detect when system is idle, globally. That is, the user is not
moving the mouse nor typing anything, in any application (not
just our program).

This is done using the GetLastInputInfo function, which records
keyboard and mouse events in the current session only; note that
this does not include remote users logged in using Terminal Server.

Platform: Windows only.
Requires ctypes; tested with Python 2.5, 2.6, 3.0 and 3.1

(C) 2009 Gabriel A. Genellina
"""

import ctypes, ctypes.wintypes

# http://msdn.microsoft.com/en-us/library/ms646272(VS.85).aspx
# typedef struct tagLASTINPUTINFO {
#     UINT cbSize;
#     DWORD dwTime;
# } LASTINPUTINFO, *PLASTINPUTINFO;

class LASTINPUTINFO(ctypes.Structure):
    _fields_ = [
      ('cbSize', ctypes.wintypes.UINT),
      ('dwTime', ctypes.wintypes.DWORD),
      ]

PLASTINPUTINFO = ctypes.POINTER(LASTINPUTINFO)

# http://msdn.microsoft.com/en-us/library/ms646302(VS.85).aspx
# BOOL GetLastInputInfo(PLASTINPUTINFO plii);

user32 = ctypes.windll.user32
GetLastInputInfo = user32.GetLastInputInfo
GetLastInputInfo.restype = ctypes.wintypes.BOOL
GetLastInputInfo.argtypes = [PLASTINPUTINFO]

kernel32 = ctypes.windll.kernel32
GetTickCount = kernel32.GetTickCount
Sleep = kernel32.Sleep

def wait_until_idle(idle_time=60):
    """Wait until no more user activity is detected.

    This function won't return until `idle_time` seconds have elapsed
    since the last user activity was detected.
    """

    idle_time_ms = int(idle_time*1000)
    liinfo = LASTINPUTINFO()
    liinfo.cbSize = ctypes.sizeof(liinfo)
    while True:
        GetLastInputInfo(ctypes.byref(liinfo))
        elapsed = GetTickCount() - liinfo.dwTime
        if elapsed>=idle_time_ms:
            break
        Sleep(idle_time_ms - elapsed or 1)


def wait_until_active(tol=5):
    """Wait until awakened by user activity.

    This function will block and wait until some user activity
    is detected. Because of the polling method used, it may return
    `tol` seconds (or less) after user activity actually began.
    """

    liinfo = LASTINPUTINFO()
    liinfo.cbSize = ctypes.sizeof(liinfo)
    lasttime = None
    delay = 1 # ms
    maxdelay = int(tol*1000)
    while True:
        GetLastInputInfo(ctypes.byref(liinfo))
        if lasttime is None: lasttime = liinfo.dwTime
        if lasttime != liinfo.dwTime:
            break
        delay = min(2*delay, maxdelay)
        Sleep(delay)

def test():
    print("Waiting for 10 seconds of no user input...")
    wait_until_idle(10)
    user32.MessageBeep(0)
    print("Ok. Now, do something!")
    wait_until_active(1)
    user32.MessageBeep(0)
    print("Done.")

if __name__=='__main__':
    test()