问题
I have a GUI application written with python+tkinter. In my workflow, I generally start the gui from the commandline, do some things in the gui and then I find myself navigating to other terminal windows to do some work. Inevitably, I want to shut down the GUI at some point, and out of habit I often just navigate to the terminal that started the GUI and send a KeyboardInterrupt (Ctrl-c). However, This interrupt is not recieved until I raise the GUI window in the Window manager. Does anyone know why this happens? If the gui is started in a single function, is there a simple workaround -- multiprocessing maybe?
回答1:
from the newsgroups:
I'm using Python 1.5 under Redhat Linux 5.0. I'm trying to figure out the best way to trap a SIGINT (or Ctrl-C) when using tkinter. To illustrate the problem I have, do the following ...
-- Build Python-1.5 with tkinter enabled.
-- Go into the Demo/tkinter/guido directory under the Python-1.5 build tree.
-- Type "python imageview.py image-file", where "image-file" is the full pathname of a displayable image.
-- Once the image pops up, make sure that the window focus is held by the xterm window from which the "python ..." command was just now invoked.
-- Hit Ctrl-C.
At this point, nothing happens. The Ctrl-C seems to be ignored. But now ...
-- Without hitting any more keys on the keyboard, set the window focus to the displayed image window.
As soon as that window gets the focus, the Ctrl-C takes effect.
My question is this: is there any way to restructure the "imageview.py" program so that it will respond to SIGINT (Ctrl-C) immediately, without having to set the window focus to the displayed image first?
Thanks in advance for any help you folks can give me.
What you're seeing is caused by the way signal handlers are handled. You're stuck in the Tcl/Tk main loop, and signal handlers are only handled by the Python interpreter. A quick workaround is to use after() to schedule a dummy function to be called once a second or so -- this will make it appear that your signal is handled in a timely manner.
--Guido van Rossum
来源：https://stackoverflow.com/questions/9998274/tkinter-keyboard-interrupt-isnt-handled-until-tkinter-frame-is-raised