231 lines
8.1 KiB
Python
231 lines
8.1 KiB
Python
"""
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Qt binding and backend selector.
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The selection logic is as follows:
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- if any of PyQt6, PySide6, PyQt5, or PySide2 have already been
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imported (checked in that order), use it;
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- otherwise, if the QT_API environment variable (used by Enthought) is set, use
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it to determine which binding to use;
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- otherwise, use whatever the rcParams indicate.
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"""
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import operator
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import os
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import platform
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import sys
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import signal
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import socket
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import contextlib
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from packaging.version import parse as parse_version
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import matplotlib as mpl
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from . import _QT_FORCE_QT5_BINDING
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QT_API_PYQT6 = "PyQt6"
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QT_API_PYSIDE6 = "PySide6"
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QT_API_PYQT5 = "PyQt5"
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QT_API_PYSIDE2 = "PySide2"
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QT_API_ENV = os.environ.get("QT_API")
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if QT_API_ENV is not None:
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QT_API_ENV = QT_API_ENV.lower()
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_ETS = { # Mapping of QT_API_ENV to requested binding.
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"pyqt6": QT_API_PYQT6, "pyside6": QT_API_PYSIDE6,
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"pyqt5": QT_API_PYQT5, "pyside2": QT_API_PYSIDE2,
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}
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# First, check if anything is already imported.
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if sys.modules.get("PyQt6.QtCore"):
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QT_API = QT_API_PYQT6
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elif sys.modules.get("PySide6.QtCore"):
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QT_API = QT_API_PYSIDE6
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elif sys.modules.get("PyQt5.QtCore"):
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QT_API = QT_API_PYQT5
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elif sys.modules.get("PySide2.QtCore"):
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QT_API = QT_API_PYSIDE2
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# Otherwise, check the QT_API environment variable (from Enthought). This can
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# only override the binding, not the backend (in other words, we check that the
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# requested backend actually matches). Use _get_backend_or_none to avoid
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# triggering backend resolution (which can result in a partially but
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# incompletely imported backend_qt5).
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elif (mpl.rcParams._get_backend_or_none() or "").lower().startswith("qt5"):
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if QT_API_ENV in ["pyqt5", "pyside2"]:
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QT_API = _ETS[QT_API_ENV]
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else:
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_QT_FORCE_QT5_BINDING = True # noqa
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QT_API = None
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# A non-Qt backend was selected but we still got there (possible, e.g., when
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# fully manually embedding Matplotlib in a Qt app without using pyplot).
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elif QT_API_ENV is None:
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QT_API = None
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elif QT_API_ENV in _ETS:
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QT_API = _ETS[QT_API_ENV]
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else:
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raise RuntimeError(
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"The environment variable QT_API has the unrecognized value {!r}; "
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"valid values are {}".format(QT_API_ENV, ", ".join(_ETS)))
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def _setup_pyqt5plus():
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global QtCore, QtGui, QtWidgets, __version__
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global _isdeleted, _to_int
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if QT_API == QT_API_PYQT6:
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from PyQt6 import QtCore, QtGui, QtWidgets, sip
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__version__ = QtCore.PYQT_VERSION_STR
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QtCore.Signal = QtCore.pyqtSignal
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QtCore.Slot = QtCore.pyqtSlot
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QtCore.Property = QtCore.pyqtProperty
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_isdeleted = sip.isdeleted
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_to_int = operator.attrgetter('value')
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elif QT_API == QT_API_PYSIDE6:
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from PySide6 import QtCore, QtGui, QtWidgets, __version__
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import shiboken6
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def _isdeleted(obj): return not shiboken6.isValid(obj)
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if parse_version(__version__) >= parse_version('6.4'):
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_to_int = operator.attrgetter('value')
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else:
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_to_int = int
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elif QT_API == QT_API_PYQT5:
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from PyQt5 import QtCore, QtGui, QtWidgets
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import sip
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__version__ = QtCore.PYQT_VERSION_STR
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QtCore.Signal = QtCore.pyqtSignal
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QtCore.Slot = QtCore.pyqtSlot
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QtCore.Property = QtCore.pyqtProperty
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_isdeleted = sip.isdeleted
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_to_int = int
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elif QT_API == QT_API_PYSIDE2:
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from PySide2 import QtCore, QtGui, QtWidgets, __version__
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try:
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from PySide2 import shiboken2
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except ImportError:
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import shiboken2
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def _isdeleted(obj):
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return not shiboken2.isValid(obj)
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_to_int = int
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else:
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raise AssertionError(f"Unexpected QT_API: {QT_API}")
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if QT_API in [QT_API_PYQT6, QT_API_PYQT5, QT_API_PYSIDE6, QT_API_PYSIDE2]:
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_setup_pyqt5plus()
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elif QT_API is None: # See above re: dict.__getitem__.
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if _QT_FORCE_QT5_BINDING:
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_candidates = [
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(_setup_pyqt5plus, QT_API_PYQT5),
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(_setup_pyqt5plus, QT_API_PYSIDE2),
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]
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else:
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_candidates = [
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(_setup_pyqt5plus, QT_API_PYQT6),
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(_setup_pyqt5plus, QT_API_PYSIDE6),
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(_setup_pyqt5plus, QT_API_PYQT5),
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(_setup_pyqt5plus, QT_API_PYSIDE2),
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]
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for _setup, QT_API in _candidates:
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try:
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_setup()
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except ImportError:
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continue
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break
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else:
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raise ImportError(
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"Failed to import any of the following Qt binding modules: {}"
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.format(", ".join([QT_API for _, QT_API in _candidates]))
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)
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else: # We should not get there.
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raise AssertionError(f"Unexpected QT_API: {QT_API}")
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_version_info = tuple(QtCore.QLibraryInfo.version().segments())
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if _version_info < (5, 12):
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raise ImportError(
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f"The Qt version imported is "
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f"{QtCore.QLibraryInfo.version().toString()} but Matplotlib requires "
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f"Qt>=5.12")
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# Fixes issues with Big Sur
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# https://bugreports.qt.io/browse/QTBUG-87014, fixed in qt 5.15.2
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if (sys.platform == 'darwin' and
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parse_version(platform.mac_ver()[0]) >= parse_version("10.16") and
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_version_info < (5, 15, 2)):
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os.environ.setdefault("QT_MAC_WANTS_LAYER", "1")
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# Backports.
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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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@contextlib.contextmanager
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def _maybe_allow_interrupt(qapp):
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"""
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This manager allows to terminate a plot by sending a SIGINT. It is
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necessary because the running Qt backend prevents Python interpreter to
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run and process signals (i.e., to raise KeyboardInterrupt exception). To
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solve this one needs to somehow wake up the interpreter and make it close
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the plot window. We do this by using the signal.set_wakeup_fd() function
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which organizes a write of the signal number into a socketpair connected
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to the QSocketNotifier (since it is part of the Qt backend, it can react
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to that write event). Afterwards, the Qt handler empties the socketpair
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by a recv() command to re-arm it (we need this if a signal different from
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SIGINT was caught by set_wakeup_fd() and we shall continue waiting). If
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the SIGINT was caught indeed, after exiting the on_signal() function the
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interpreter reacts to the SIGINT according to the handle() function which
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had been set up by a signal.signal() call: it causes the qt_object to
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exit by calling its quit() method. Finally, we call the old SIGINT
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handler with the same arguments that were given to our custom handle()
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handler.
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We do this only if the old handler for SIGINT was not None, which means
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that a non-python handler was installed, i.e. in Julia, and not SIG_IGN
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which means we should ignore the interrupts.
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"""
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old_sigint_handler = signal.getsignal(signal.SIGINT)
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if old_sigint_handler in (None, signal.SIG_IGN, signal.SIG_DFL):
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yield
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return
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handler_args = None
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wsock, rsock = socket.socketpair()
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wsock.setblocking(False)
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rsock.setblocking(False)
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old_wakeup_fd = signal.set_wakeup_fd(wsock.fileno())
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sn = QtCore.QSocketNotifier(rsock.fileno(), QtCore.QSocketNotifier.Type.Read)
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# We do not actually care about this value other than running some Python code to
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# ensure that the interpreter has a chance to handle the signal in Python land. We
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# also need to drain the socket because it will be written to as part of the wakeup!
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# There are some cases where this may fire too soon / more than once on Windows so
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# we should be forgiving about reading an empty socket.
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# Clear the socket to re-arm the notifier.
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@sn.activated.connect
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def _may_clear_sock(*args):
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try:
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rsock.recv(1)
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except BlockingIOError:
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pass
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def handle(*args):
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nonlocal handler_args
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handler_args = args
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qapp.quit()
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signal.signal(signal.SIGINT, handle)
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try:
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yield
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finally:
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wsock.close()
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rsock.close()
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sn.setEnabled(False)
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signal.set_wakeup_fd(old_wakeup_fd)
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signal.signal(signal.SIGINT, old_sigint_handler)
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if handler_args is not None:
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old_sigint_handler(*handler_args)
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