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qt.py
69 lines | 2.6 KiB | text/x-python | PythonLexer
import sys
import os
from IPython.external.qt_for_kernel import QtCore, QtGui
from IPython import get_ipython
# If we create a QApplication, keep a reference to it so that it doesn't get
# garbage collected.
_appref = None
_already_warned = False
def _reclaim_excepthook():
shell = get_ipython()
if shell is not None:
sys.excepthook = shell.excepthook
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([" "])
# "reclaim" IPython sys.excepthook after event loop starts
# without this, it defaults back to BaseIPythonApplication.excepthook
# and exceptions in the Qt event loop are rendered without traceback
# formatting and look like "bug in IPython".
QtCore.QTimer.singleShot(0, _reclaim_excepthook)
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)