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import sys
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import os
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#`qt_for_kernel` will import the "best" qt version
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from IPython.external.qt_for_kernel import QtCore, QtGui, enum_helper
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from IPython import get_ipython
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# If we create a QApplication, keep a reference to it so that it doesn't get
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# garbage collected.
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_appref = None
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_already_warned = False
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def _exec(obj):
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# exec on PyQt6, exec_ elsewhere.
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obj.exec() if hasattr(obj, "exec") else obj.exec_()
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def _reclaim_excepthook():
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shell = get_ipython()
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if shell is not None:
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sys.excepthook = shell.excepthook
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def inputhook(context):
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global _appref
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app = QtCore.QCoreApplication.instance()
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if not app:
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if sys.platform == 'linux':
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if not os.environ.get('DISPLAY') \
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and not os.environ.get('WAYLAND_DISPLAY'):
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import warnings
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global _already_warned
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if not _already_warned:
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_already_warned = True
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warnings.warn(
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'The DISPLAY or WAYLAND_DISPLAY environment variable is '
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'not set or empty and Qt5 requires this environment '
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'variable. Deactivate Qt5 code.'
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)
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return
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try:
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QtCore.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
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except AttributeError: # Only for Qt>=5.6, <6.
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pass
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try:
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QtCore.QApplication.setHighDpiScaleFactorRoundingPolicy(
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QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough
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)
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except AttributeError: # Only for Qt>=5.14.
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pass
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_appref = app = QtGui.QApplication([" "])
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# "reclaim" IPython sys.excepthook after event loop starts
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# without this, it defaults back to BaseIPythonApplication.excepthook
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# and exceptions in the Qt event loop are rendered without traceback
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# formatting and look like "bug in IPython".
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QtCore.QTimer.singleShot(0, _reclaim_excepthook)
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event_loop = QtCore.QEventLoop(app)
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print(f'`inputhook` running Qt {QtCore.qVersion()} event loop.\r')
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if sys.platform == 'win32':
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# The QSocketNotifier method doesn't appear to work on Windows.
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# Use polling instead.
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timer = QtCore.QTimer()
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timer.timeout.connect(event_loop.quit)
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while not context.input_is_ready():
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# NOTE: run the event loop, and after 50 ms, call `quit` to exit it.
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timer.start(50) # 50 ms
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_exec(event_loop)
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timer.stop()
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else:
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# On POSIX platforms, we can use a file descriptor to quit the event
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# loop when there is input ready to read.
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notifier = QtCore.QSocketNotifier(
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context.fileno(), enum_helper("QtCore.QSocketNotifier.Type").Read
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)
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try:
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# connect the callback we care about before we turn it on
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# lambda is necessary as PyQT inspect the function signature to know
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# what arguments to pass to. See https://github.com/ipython/ipython/pull/12355
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notifier.activated.connect(lambda: event_loop.exit())
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notifier.setEnabled(True)
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# only start the event loop we are not already flipped
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if not context.input_is_ready():
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_exec(event_loop)
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finally:
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notifier.setEnabled(False)
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