"""
This module contains factory functions that attempt
to return Qt submodules from the various python Qt bindings.
It also protects against double-importing Qt with different
bindings, which is unstable and likely to crash
This is used primarily by qt and qt_for_kernel, and shouldn't
be accessed directly from the outside
"""
import sys
import types
from functools import partial
from importlib import import_module
from IPython.utils.version import check_version
# Available APIs.
QT_API_PYQT = 'pyqt' # Force version 2
QT_API_PYQT5 = 'pyqt5'
QT_API_PYQTv1 = 'pyqtv1' # Force version 2
QT_API_PYQT_DEFAULT = 'pyqtdefault' # use system default for version 1 vs. 2
QT_API_PYSIDE = 'pyside'
QT_API_PYSIDE2 = 'pyside2'
api_to_module = {QT_API_PYSIDE2: 'PySide2',
QT_API_PYSIDE: 'PySide',
QT_API_PYQT: 'PyQt4',
QT_API_PYQTv1: 'PyQt4',
QT_API_PYQT5: 'PyQt5',
QT_API_PYQT_DEFAULT: 'PyQt4',
}
class ImportDenier(object):
"""Import Hook that will guard against bad Qt imports
once IPython commits to a specific binding
"""
def __init__(self):
self.__forbidden = set()
def forbid(self, module_name):
sys.modules.pop(module_name, None)
self.__forbidden.add(module_name)
def find_module(self, fullname, path=None):
if path:
return
if fullname in self.__forbidden:
return self
def load_module(self, fullname):
raise ImportError("""
Importing %s disabled by IPython, which has
already imported an Incompatible QT Binding: %s
""" % (fullname, loaded_api()))
ID = ImportDenier()
sys.meta_path.insert(0, ID)
def commit_api(api):
"""Commit to a particular API, and trigger ImportErrors on subsequent
dangerous imports"""
if api == QT_API_PYSIDE2:
ID.forbid('PySide')
ID.forbid('PyQt4')
ID.forbid('PyQt5')
if api == QT_API_PYSIDE:
ID.forbid('PySide2')
ID.forbid('PyQt4')
ID.forbid('PyQt5')
elif api == QT_API_PYQT5:
ID.forbid('PySide2')
ID.forbid('PySide')
ID.forbid('PyQt4')
else: # There are three other possibilities, all representing PyQt4
ID.forbid('PyQt5')
ID.forbid('PySide2')
ID.forbid('PySide')
def loaded_api():
"""Return which API is loaded, if any
If this returns anything besides None,
importing any other Qt binding is unsafe.
Returns
-------
None, 'pyside2', 'pyside', 'pyqt', 'pyqt5', or 'pyqtv1'
"""
if 'PyQt4.QtCore' in sys.modules:
if qtapi_version() == 2:
return QT_API_PYQT
else:
return QT_API_PYQTv1
elif 'PySide.QtCore' in sys.modules:
return QT_API_PYSIDE
elif 'PySide2.QtCore' in sys.modules:
return QT_API_PYSIDE2
elif 'PyQt5.QtCore' in sys.modules:
return QT_API_PYQT5
return None
def has_binding(api):
"""Safely check for PyQt4/5, PySide or PySide2, without importing submodules
Supports Python <= 3.3
Parameters
----------
api : str [ 'pyqtv1' | 'pyqt' | 'pyqt5' | 'pyside' | 'pyside2' | 'pyqtdefault']
Which module to check for
Returns
-------
True if the relevant module appears to be importable
"""
# we can't import an incomplete pyside and pyqt4
# this will cause a crash in sip (#1431)
# check for complete presence before importing
module_name = api_to_module[api]
import imp
try:
#importing top level PyQt4/PySide module is ok...
mod = import_module(module_name)
#...importing submodules is not
imp.find_module('QtCore', mod.__path__)
imp.find_module('QtGui', mod.__path__)
imp.find_module('QtSvg', mod.__path__)
if api in (QT_API_PYQT5, QT_API_PYSIDE2):
# QT5 requires QtWidgets too
imp.find_module('QtWidgets', mod.__path__)
#we can also safely check PySide version
if api == QT_API_PYSIDE:
return check_version(mod.__version__, '1.0.3')
else:
return True
except ImportError:
return False
def has_binding_new(api):
"""Safely check for PyQt4/5, PySide or PySide2, without importing submodules
Supports Python >= 3.4
Parameters
----------
api : str [ 'pyqtv1' | 'pyqt' | 'pyqt5' | 'pyside' | 'pyside2' | 'pyqtdefault']
Which module to check for
Returns
-------
True if the relevant module appears to be importable
"""
module_name = api_to_module[api]
from importlib.util import find_spec
required = ['QtCore', 'QtGui', 'QtSvg']
if api in (QT_API_PYQT5, QT_API_PYSIDE2):
# QT5 requires QtWidgets too
required.append('QtWidgets')
for submod in required:
try:
spec = find_spec('%s.%s' % (module_name, submod))
except ImportError:
# Package (e.g. PyQt5) not found
return False
else:
if spec is None:
# Submodule (e.g. PyQt5.QtCore) not found
return False
if api == QT_API_PYSIDE:
# We can also safely check PySide version
import PySide
return check_version(PySide.__version__, '1.0.3')
return True
if sys.version_info >= (3, 4):
has_binding = has_binding_new
def qtapi_version():
"""Return which QString API has been set, if any
Returns
-------
The QString API version (1 or 2), or None if not set
"""
try:
import sip
except ImportError:
return
try:
return sip.getapi('QString')
except ValueError:
return
def can_import(api):
"""Safely query whether an API is importable, without importing it"""
if not has_binding(api):
return False
current = loaded_api()
if api == QT_API_PYQT_DEFAULT:
return current in [QT_API_PYQT, QT_API_PYQTv1, None]
else:
return current in [api, None]
def import_pyqt4(version=2):
"""
Import PyQt4
Parameters
----------
version : 1, 2, or None
Which QString/QVariant API to use. Set to None to use the system
default
ImportErrors rasied within this function are non-recoverable
"""
# The new-style string API (version=2) automatically
# converts QStrings to Unicode Python strings. Also, automatically unpacks
# QVariants to their underlying objects.
import sip
if version is not None:
sip.setapi('QString', version)
sip.setapi('QVariant', version)
from PyQt4 import QtGui, QtCore, QtSvg
if not check_version(QtCore.PYQT_VERSION_STR, '4.7'):
raise ImportError("IPython requires PyQt4 >= 4.7, found %s" %
QtCore.PYQT_VERSION_STR)
# Alias PyQt-specific functions for PySide compatibility.
QtCore.Signal = QtCore.pyqtSignal
QtCore.Slot = QtCore.pyqtSlot
# query for the API version (in case version == None)
version = sip.getapi('QString')
api = QT_API_PYQTv1 if version == 1 else QT_API_PYQT
return QtCore, QtGui, QtSvg, api
def import_pyqt5():
"""
Import PyQt5
ImportErrors rasied within this function are non-recoverable
"""
import sip
from PyQt5 import QtCore, QtSvg, QtWidgets, QtGui
# Alias PyQt-specific functions for PySide compatibility.
QtCore.Signal = QtCore.pyqtSignal
QtCore.Slot = QtCore.pyqtSlot
# Join QtGui and QtWidgets for Qt4 compatibility.
QtGuiCompat = types.ModuleType('QtGuiCompat')
QtGuiCompat.__dict__.update(QtGui.__dict__)
QtGuiCompat.__dict__.update(QtWidgets.__dict__)
api = QT_API_PYQT5
return QtCore, QtGuiCompat, QtSvg, api
def import_pyside():
"""
Import PySide
ImportErrors raised within this function are non-recoverable
"""
from PySide import QtGui, QtCore, QtSvg
return QtCore, QtGui, QtSvg, QT_API_PYSIDE
def import_pyside2():
"""
Import PySide2
ImportErrors raised within this function are non-recoverable
"""
from PySide2 import QtGui, QtCore, QtSvg, QtWidgets, QtPrintSupport
# Join QtGui and QtWidgets for Qt4 compatibility.
QtGuiCompat = types.ModuleType('QtGuiCompat')
QtGuiCompat.__dict__.update(QtGui.__dict__)
QtGuiCompat.__dict__.update(QtWidgets.__dict__)
QtGuiCompat.__dict__.update(QtPrintSupport.__dict__)
return QtCore, QtGuiCompat, QtSvg, QT_API_PYSIDE2
def load_qt(api_options):
"""
Attempt to import Qt, given a preference list
of permissible bindings
It is safe to call this function multiple times.
Parameters
----------
api_options: List of strings
The order of APIs to try. Valid items are 'pyside', 'pyside2',
'pyqt', 'pyqt5', 'pyqtv1' and 'pyqtdefault'
Returns
-------
A tuple of QtCore, QtGui, QtSvg, QT_API
The first three are the Qt modules. The last is the
string indicating which module was loaded.
Raises
------
ImportError, if it isn't possible to import any requested
bindings (either becaues they aren't installed, or because
an incompatible library has already been installed)
"""
loaders = {
QT_API_PYSIDE2: import_pyside2,
QT_API_PYSIDE: import_pyside,
QT_API_PYQT: import_pyqt4,
QT_API_PYQT5: import_pyqt5,
QT_API_PYQTv1: partial(import_pyqt4, version=1),
QT_API_PYQT_DEFAULT: partial(import_pyqt4, version=None)
}
for api in api_options:
if api not in loaders:
raise RuntimeError(
"Invalid Qt API %r, valid values are: %s" %
(api, ", ".join(["%r" % k for k in loaders.keys()])))
if not can_import(api):
continue
#cannot safely recover from an ImportError during this
result = loaders[api]()
api = result[-1] # changed if api = QT_API_PYQT_DEFAULT
commit_api(api)
return result
else:
raise ImportError("""
Could not load requested Qt binding. Please ensure that
PyQt4 >= 4.7, PyQt5, PySide >= 1.0.3 or PySide2 is available,
and only one is imported per session.
Currently-imported Qt library: %r
PyQt4 available (requires QtCore, QtGui, QtSvg): %s
PyQt5 available (requires QtCore, QtGui, QtSvg, QtWidgets): %s
PySide >= 1.0.3 installed: %s
PySide2 installed: %s
Tried to load: %r
""" % (loaded_api(),
has_binding(QT_API_PYQT),
has_binding(QT_API_PYQT5),
has_binding(QT_API_PYSIDE),
has_binding(QT_API_PYSIDE2),
api_options))