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qt_for_kernel.py
84 lines | 2.3 KiB | text/x-python | PythonLexer
""" Import Qt in a manner suitable for an IPython kernel.
This is the import used for the `gui=qt` or `matplotlib=qt` initialization.
Import Priority:
if Qt4 has been imported anywhere else:
use that
if matplotlib has been imported and doesn't support v2 (<= 1.0.1):
use PyQt4 @v1
Next, ask ETS' QT_API env variable
if QT_API not set:
ask matplotlib via rcParams['backend.qt4']
if it said PyQt:
use PyQt4 @v1
elif it said PySide:
use PySide
else: (matplotlib said nothing)
# this is the default path - nobody told us anything
try:
PyQt @v1
except:
fallback on PySide
else:
use PyQt @v2 or PySide, depending on QT_API
because ETS doesn't work with PyQt @v1.
"""
import os
import sys
from IPython.utils.warn import warn
from IPython.utils.version import check_version
from IPython.external.qt_loaders import (load_qt, QT_API_PYSIDE,
QT_API_PYQT, QT_API_PYQT_DEFAULT,
loaded_api)
#Constraints placed on an imported matplotlib
def matplotlib_options(mpl):
if mpl is None:
return
mpqt = mpl.rcParams.get('backend.qt4', None)
if mpqt is None:
return None
if mpqt.lower() == 'pyside':
return [QT_API_PYSIDE]
elif mpqt.lower() == 'pyqt4':
return [QT_API_PYQT_DEFAULT]
raise ImportError("unhandled value for backend.qt4 from matplotlib: %r" %
mpqt)
def get_options():
"""Return a list of acceptable QT APIs, in decreasing order of
preference
"""
#already imported Qt somewhere. Use that
loaded = loaded_api()
if loaded is not None:
return [loaded]
mpl = sys.modules.get('matplotlib', None)
if mpl is not None and not check_version(mpl.__version__, '1.0.2'):
#1.0.1 only supports PyQt4 v1
return [QT_API_PYQT_DEFAULT]
if os.environ.get('QT_API', None) is None:
#no ETS variable. Ask mpl, then use either
return matplotlib_options(mpl) or [QT_API_PYQT_DEFAULT, QT_API_PYSIDE]
#ETS variable present. Will fallback to external.qt
return None
api_opts = get_options()
if api_opts is not None:
QtCore, QtGui, QtSvg, QT_API = load_qt(api_opts)
else: # use ETS variable
from IPython.external.qt import QtCore, QtGui, QtSvg, QT_API