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qt.py
90 lines | 3.3 KiB | text/x-python | PythonLexer
import sys
import os
from IPython.external.qt_for_kernel import QtCore, QtGui, enum_helper
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 _exec(obj):
# exec on PyQt6, exec_ elsewhere.
obj.exec() if hasattr(obj, "exec") else obj.exec_()
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
try:
QtCore.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
except AttributeError: # Only for Qt>=5.6, <6.
pass
try:
QtCore.QApplication.setHighDpiScaleFactorRoundingPolicy(
QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough
)
except AttributeError: # Only for Qt>=5.14.
pass
_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():
# NOTE: run the event loop, and after 50 ms, call `quit` to exit it.
timer.start(50) # 50 ms
_exec(event_loop)
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(), enum_helper("QtCore.QSocketNotifier.Type").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():
_exec(event_loop)
finally:
notifier.setEnabled(False)
# This makes sure that the event loop is garbage collected.
# See issue 14240.
event_loop.setParent(None)