Capture change in active window (for linux)
Is there a way to know when a (linux x windows) user changes the active window through alt-tab or click. I want to write a script that listens for this event (if such an event occurs, the script then goes on to find the current active window - which I know how to solve). I could also keep polling to find the current active window but that's a bad way to write this. Hoping to get a solution tha开发者_JS百科t can "listen" rather than "poll".
Thanks!
I had a need to do that and my solution was to watch the _NET_ACTIVE_WINDOW
property (maintained by the Window Manager) on the root window for changes.
Here's a copy of the python-xlib implementation I wrote to demonstrate it to someone:
import Xlib
import Xlib.display
disp = Xlib.display.Display()
root = disp.screen().root
NET_ACTIVE_WINDOW = disp.intern_atom('_NET_ACTIVE_WINDOW')
NET_WM_NAME = disp.intern_atom('_NET_WM_NAME')
last_seen = {'xid': None}
def get_active_window():
window_id = root.get_full_property(NET_ACTIVE_WINDOW,
Xlib.X.AnyPropertyType).value[0]
focus_changed = (window_id != last_seen['xid'])
last_seen['xid'] = window_id
return window_id, focus_changed
def get_window_name(window_id):
try:
window_obj = disp.create_resource_object('window', window_id)
window_name = window_obj.get_full_property(NET_WM_NAME, 0).value
except Xlib.error.XError:
window_name = None
return window_name
if __name__ == '__main__':
root.change_attributes(event_mask=Xlib.X.PropertyChangeMask)
while True:
win, changed = get_active_window()
if changed:
print(get_window_name(win))
while True:
event = disp.next_event()
if (event.type == Xlib.X.PropertyNotify and
event.atom == NET_ACTIVE_WINDOW):
break
The more fully-commented version is in this gist.
Just briefly looking through the documentation for the Perl module X11::Tops indicates that there is a monitor_property_and_structure_change method. I would thus guess that the underlying X11 libraries will provide the functionality you are looking for.
I know about KTimeTracker KDE program which tracks how much time you've spend in each window. I don't know about details - whether it tracks events of changing active windows, or just periodically checks status of whole desktop. Nevertheless, sources might be helpful : http://www.kde.org/applications/utilities/ktimetracker/ .
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