"""

Qt binding and backend selector.

The selection logic is as follows:

- if any of PyQt6, PySide6, or PyQt5 have already been

imported (checked in that order), use it;

- otherwise, if the QT_API environment variable (used by Enthought) is set, use

it to determine which binding to use;

- otherwise, use whatever the rcParams indicate.

"""

import operator

import os

import platform

import sys

from packaging.version import parse as parse_version

import matplotlib as mpl

from . import _QT_FORCE_QT5_BINDING

QT_API_PYQT6 = "PyQt6"

QT_API_PYSIDE6 = "PySide6"

QT_API_PYQT5 = "PyQt5"

QT_API_ENV = os.environ.get("QT_API")

if QT_API_ENV is not None:

QT_API_ENV = QT_API_ENV.lower()

_ETS = { # Mapping of QT_API_ENV to requested binding.

"pyqt6": QT_API_PYQT6, "pyside6": QT_API_PYSIDE6,

"pyqt5": QT_API_PYQT5,

}

# First, check if anything is already imported.

if sys.modules.get("PyQt6.QtCore"):

QT_API = QT_API_PYQT6

elif sys.modules.get("PySide6.QtCore"):

QT_API = QT_API_PYSIDE6

elif sys.modules.get("PyQt5.QtCore"):

QT_API = QT_API_PYQT5

# Otherwise, check the QT_API environment variable (from Enthought). This can

# only override the binding, not the backend (in other words, we check that the

# requested backend actually matches). Use _get_backend_or_none to avoid

# triggering backend resolution (which can result in a partially but

# incompletely imported backend_qt5).

elif (mpl.rcParams._get_backend_or_none() or "").lower().startswith("qt5"):

if QT_API_ENV == "pyqt5":

QT_API = _ETS[QT_API_ENV]

else:

_QT_FORCE_QT5_BINDING = True # noqa: F811

QT_API = None

# A non-Qt backend was selected but we still got there (possible, e.g., when

# fully manually embedding Matplotlib in a Qt app without using pyplot).

elif QT_API_ENV is None:

QT_API = None

elif QT_API_ENV in _ETS:

QT_API = _ETS[QT_API_ENV]

else:

raise RuntimeError(

"The environment variable QT_API has the unrecognized value {!r}; "

"valid values are {}".format(QT_API_ENV, ", ".join(_ETS)))

def _setup_pyqt5plus():

global QtCore, QtGui, QtWidgets, QtSvg, __version__

global _isdeleted, _to_int

if QT_API == QT_API_PYQT6:

from PyQt6 import QtCore, QtGui, QtWidgets, sip, QtSvg

__version__ = QtCore.PYQT_VERSION_STR

QtCore.Signal = QtCore.pyqtSignal

QtCore.Slot = QtCore.pyqtSlot

QtCore.Property = QtCore.pyqtProperty

_isdeleted = sip.isdeleted

_to_int = operator.attrgetter('value')

elif QT_API == QT_API_PYSIDE6:

from PySide6 import QtCore, QtGui, QtWidgets, QtSvg, __version__

import shiboken6

def _isdeleted(obj): return not shiboken6.isValid(obj)

if parse_version(__version__) >= parse_version('6.4'):

_to_int = operator.attrgetter('value')

else:

_to_int = int

elif QT_API == QT_API_PYQT5:

from PyQt5 import QtCore, QtGui, QtWidgets, QtSvg

import sip

__version__ = QtCore.PYQT_VERSION_STR

QtCore.Signal = QtCore.pyqtSignal

QtCore.Slot = QtCore.pyqtSlot

QtCore.Property = QtCore.pyqtProperty

_isdeleted = sip.isdeleted

_to_int = int

else:

raise AssertionError(f"Unexpected QT_API: {QT_API}")

if QT_API in [QT_API_PYQT6, QT_API_PYQT5, QT_API_PYSIDE6]:

_setup_pyqt5plus()

elif QT_API is None: # See above re: dict.__getitem__.

if _QT_FORCE_QT5_BINDING:

_candidates = [

(_setup_pyqt5plus, QT_API_PYQT5),

]

else:

_candidates = [

(_setup_pyqt5plus, QT_API_PYQT6),

(_setup_pyqt5plus, QT_API_PYSIDE6),

(_setup_pyqt5plus, QT_API_PYQT5),

]

for _setup, QT_API in _candidates:

try:

_setup()

except ImportError:

continue

break

else:

raise ImportError(

"Failed to import any of the following Qt binding modules: {}"

.format(", ".join([QT_API for _, QT_API in _candidates]))

)

else: # We should not get there.

raise AssertionError(f"Unexpected QT_API: {QT_API}")

_version_info = tuple(QtCore.QLibraryInfo.version().segments())

if _version_info < (5, 12):

raise ImportError(

f"The Qt version imported is "

f"{QtCore.QLibraryInfo.version().toString()} but Matplotlib requires "

f"Qt>=5.12")

# Fixes issues with Big Sur

# https://bugreports.qt.io/browse/QTBUG-87014, fixed in qt 5.15.2

if (sys.platform == 'darwin' and

parse_version(platform.mac_ver()[0]) >= parse_version("10.16") and

_version_info < (5, 15, 2)):

os.environ.setdefault("QT_MAC_WANTS_LAYER", "1")

# Backports.

def _exec(obj):

# exec on PyQt6, exec_ elsewhere.

obj.exec() if hasattr(obj, "exec") else obj.exec_()