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# -*- coding: utf-8 -*-
Qt4's inputhook support function
Author: Christian Boos
# Copyright (C) 2011 The IPython Development Team
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
# Imports
from IPython.external.qt_for_kernel import QtCore, QtGui
from IPython.lib.inputhook import stdin_ready
# Code
def create_inputhook_qt4(mgr, app=None):
"""Create an input hook for running the Qt4 application event loop.
mgr : an InputHookManager
app : Qt Application, optional.
Running application to use. If not given, we probe Qt for an
existing application object, and create a new one if none is found.
A pair consisting of a Qt Application (either the one given or the
one found or created) and a inputhook.
We use a custom input hook instead of PyQt4's default one, as it
interacts better with the readline packages (issue #481).
The inputhook function works in tandem with a 'pre_prompt_hook'
which automatically restores the hook as an inputhook in case the
latter has been temporarily disabled after having intercepted a
if app is None:
app = QtCore.QCoreApplication.instance()
if app is None:
app = QtGui.QApplication([" "])
# Re-use previously created inputhook if any
ip = get_ipython()
if hasattr(ip, '_inputhook_qt4'):
return app, ip._inputhook_qt4
# Otherwise create the inputhook_qt4/preprompthook_qt4 pair of
# hooks (they both share the got_kbdint flag)
got_kbdint = [False]
def inputhook_qt4():
"""PyOS_InputHook python hook for Qt4.
Process pending Qt events and if there's no pending keyboard
input, spend a short slice of time (50ms) running the Qt event
As a Python ctypes callback can't raise an exception, we catch
the KeyboardInterrupt and temporarily deactivate the hook,
which will let a *second* CTRL+C be processed normally and go
back to a clean prompt line.
app = QtCore.QCoreApplication.instance()
app.processEvents(QtCore.QEventLoop.AllEvents, 300)
if not stdin_ready():
timer = QtCore.QTimer()
while not stdin_ready():
except KeyboardInterrupt:
got_kbdint[0] = True
print("\n(event loop interrupted - "
"hit CTRL+C again to clear the prompt)")
return 0
def preprompthook_qt4(ishell):
"""'pre_prompt_hook' used to restore the Qt4 input hook
(in case the latter was temporarily deactivated after a
if got_kbdint[0]:
got_kbdint[0] = False
ip._inputhook_qt4 = inputhook_qt4
ip.set_hook('pre_prompt_hook', preprompthook_qt4)
return app, inputhook_qt4
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