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# -*- coding: utf-8 -*-
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"""
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Qt4's inputhook support function
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Author: Christian Boos
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"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2011 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# Imports
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#-----------------------------------------------------------------------------
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from IPython.core.interactiveshell import InteractiveShell
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from IPython.external.qt_for_kernel import QtCore, QtGui
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from IPython.lib.inputhook import allow_CTRL_C, ignore_CTRL_C, stdin_ready
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#-----------------------------------------------------------------------------
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# Code
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#-----------------------------------------------------------------------------
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def create_inputhook_qt4(mgr, app=None):
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"""Create an input hook for running the Qt4 application event loop.
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Parameters
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----------
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mgr : an InputHookManager
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app : Qt Application, optional.
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Running application to use. If not given, we probe Qt for an
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existing application object, and create a new one if none is found.
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Returns
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-------
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A pair consisting of a Qt Application (either the one given or the
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one found or created) and a inputhook.
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Notes
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-----
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We use a custom input hook instead of PyQt4's default one, as it
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interacts better with the readline packages (issue #481).
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The inputhook function works in tandem with a 'pre_prompt_hook'
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which automatically restores the hook as an inputhook in case the
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latter has been temporarily disabled after having intercepted a
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KeyboardInterrupt.
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"""
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if app is None:
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app = QtCore.QCoreApplication.instance()
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if app is None:
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app = QtGui.QApplication([" "])
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# Re-use previously created inputhook if any
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ip = InteractiveShell.instance()
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if hasattr(ip, '_inputhook_qt4'):
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return app, ip._inputhook_qt4
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# Otherwise create the inputhook_qt4/preprompthook_qt4 pair of
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# hooks (they both share the got_kbdint flag)
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got_kbdint = [False]
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def inputhook_qt4():
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"""PyOS_InputHook python hook for Qt4.
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Process pending Qt events and if there's no pending keyboard
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input, spend a short slice of time (50ms) running the Qt event
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loop.
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As a Python ctypes callback can't raise an exception, we catch
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the KeyboardInterrupt and temporarily deactivate the hook,
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which will let a *second* CTRL+C be processed normally and go
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back to a clean prompt line.
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"""
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try:
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allow_CTRL_C()
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app = QtCore.QCoreApplication.instance()
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if not app: # shouldn't happen, but safer if it happens anyway...
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return 0
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app.processEvents(QtCore.QEventLoop.AllEvents, 300)
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if not stdin_ready():
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timer = QtCore.QTimer()
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timer.timeout.connect(app.quit)
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while not stdin_ready():
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timer.start(50)
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app.exec_()
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timer.stop()
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ignore_CTRL_C()
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except KeyboardInterrupt:
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ignore_CTRL_C()
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got_kbdint[0] = True
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print("\nKeyboardInterrupt - qt4 event loop interrupted!"
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"\n * hit CTRL+C again to clear the prompt"
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"\n * use '%gui none' to disable the event loop"
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" permanently"
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"\n and '%gui qt4' to re-enable it later")
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mgr.clear_inputhook()
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except: # NO exceptions are allowed to escape from a ctypes callback
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mgr.clear_inputhook()
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from traceback import print_exc
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print_exc()
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print("Got exception from inputhook_qt4, unregistering.")
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return 0
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def preprompthook_qt4(ishell):
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"""'pre_prompt_hook' used to restore the Qt4 input hook
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(in case the latter was temporarily deactivated after a
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CTRL+C)
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"""
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if got_kbdint[0]:
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mgr.set_inputhook(inputhook_qt4)
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got_kbdint[0] = False
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ip._inputhook_qt4 = inputhook_qt4
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ip.set_hook('pre_prompt_hook', preprompthook_qt4)
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return app, inputhook_qt4
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