import sys import os from IPython.external.qt_for_kernel import QtCore, QtGui # If we create a QApplication, keep a reference to it so that it doesn't get # garbage collected. _appref = None _already_warned = False def inputhook(context): global _appref app = QtCore.QCoreApplication.instance() if not app: if sys.platform == 'linux': if not os.environ.get('DISPLAY') \ and not os.environ.get('WAYLAND_DISPLAY'): import warnings global _already_warned if not _already_warned: _already_warned = True warnings.warn( 'The DISPLAY or WAYLAND_DISPLAY environment variable is ' 'not set or empty and Qt5 requires this environment ' 'variable. Deactivate Qt5 code.' ) return QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling) _appref = app = QtGui.QApplication([" "]) event_loop = QtCore.QEventLoop(app) if sys.platform == 'win32': # The QSocketNotifier method doesn't appear to work on Windows. # Use polling instead. timer = QtCore.QTimer() timer.timeout.connect(event_loop.quit) while not context.input_is_ready(): timer.start(50) # 50 ms event_loop.exec_() timer.stop() else: # On POSIX platforms, we can use a file descriptor to quit the event # loop when there is input ready to read. notifier = QtCore.QSocketNotifier(context.fileno(), QtCore.QSocketNotifier.Read) try: # connect the callback we care about before we turn it on # lambda is necessary as PyQT inspect the function signature to know # what arguments to pass to. See https://github.com/ipython/ipython/pull/12355 notifier.activated.connect(lambda: event_loop.exit()) notifier.setEnabled(True) # only start the event loop we are not already flipped if not context.input_is_ready(): event_loop.exec_() finally: notifier.setEnabled(False)