qtpy/__init__.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 # Copyright © 2009- The Spyder Development Team
   4 # Copyright © 2014-2015 Colin Duquesnoy
   5 #
   6 # Licensed under the terms of the MIT License
   7 # (see LICENSE.txt for details)
   8
   9 """
  10 **QtPy** is a shim over the various Python Qt bindings. It is used to write
  11 Qt binding indenpendent libraries or applications.
  12
  13 If one of the APIs has already been imported, then it will be used.
  14
  15 Otherwise, the shim will automatically select the first available API (PyQt5,
  16 PySide2, PyQt4 and finally PySide); in that case, you can force the use of one
  17 specific bindings (e.g. if your application is using one specific bindings and
  18 you need to use library that use QtPy) by setting up the ``QT_API`` environment
  19 variable.
  20
  21 PyQt5
  22 =====
  23
  24 For PyQt5, you don't have to set anything as it will be used automatically::
  25
  26     >>> from qtpy import QtGui, QtWidgets, QtCore
  27     >>> print(QtWidgets.QWidget)
  28
  29
  30 PySide2
  31 ======
  32
  33 Set the QT_API environment variable to 'pyside2' before importing other
  34 packages::
  35
  36     >>> import os
  37     >>> os.environ['QT_API'] = 'pyside2'
  38     >>> from qtpy import QtGui, QtWidgets, QtCore
  39     >>> print(QtWidgets.QWidget)
  40
  41 PyQt4
  42 =====
  43
  44 Set the ``QT_API`` environment variable to 'pyqt' before importing any python
  45 package::
  46
  47     >>> import os
  48     >>> os.environ['QT_API'] = 'pyqt'
  49     >>> from qtpy import QtGui, QtWidgets, QtCore
  50     >>> print(QtWidgets.QWidget)
  51
  52 PySide
  53 ======
  54
  55 Set the QT_API environment variable to 'pyside' before importing other
  56 packages::
  57
  58     >>> import os
  59     >>> os.environ['QT_API'] = 'pyside'
  60     >>> from qtpy import QtGui, QtWidgets, QtCore
  61     >>> print(QtWidgets.QWidget)
  62
  63 """
  64
  65 import os
  66 import sys
  67 import warnings
  68
  69 # Version of QtPy
  70 from ._version import __version__
  71
  72
  73 class PythonQtError(Exception):
  74     """Error raise if no bindings could be selected"""
  75     pass
  76
  77
  78 class PythonQtWarning(Warning):
  79     """Warning if some features are not implemented in a binding."""
  80     pass
  81
  82
  83 # Qt API environment variable name
  84 QT_API = 'QT_API'
  85
  86 # Names of the expected PyQt5 api
  87 PYQT5_API = ['pyqt5']
  88
  89 # Names of the expected PyQt4 api
  90 PYQT4_API = [
  91     'pyqt',  # name used in IPython.qt
  92     'pyqt4'  # pyqode.qt original name
  93 ]
  94
  95 # Names of the expected PySide api
  96 PYSIDE_API = ['pyside']
  97
  98 # Names of the expected PySide2 api
  99 PYSIDE2_API = ['pyside2']
 100
 101 # Setting a default value for QT_API
 102 os.environ.setdefault(QT_API, 'pyqt5')
 103
 104 API = os.environ[QT_API].lower()
 105 initial_api = API
 106 assert API in (PYQT5_API + PYQT4_API + PYSIDE_API + PYSIDE2_API)
 107
 108 is_old_pyqt = is_pyqt46 = False
 109 PYQT5 = True
 110 PYQT4 = PYSIDE = PYSIDE2 = False
 111
 112
 113 if 'PyQt5' in sys.modules:
 114     API = 'pyqt5'
 115 elif 'PySide2' in sys.modules:
 116     API = 'pyside2'
 117 elif 'PyQt4' in sys.modules:
 118     API = 'pyqt4'
 119 elif 'PySide' in sys.modules:
 120     API = 'pyside'
 121
 122
 123 if API in PYQT5_API:
 124     try:
 125         from PyQt5.QtCore import PYQT_VERSION_STR as PYQT_VERSION  # analysis:ignore
 126         from PyQt5.QtCore import QT_VERSION_STR as QT_VERSION  # analysis:ignore
 127         PYSIDE_VERSION = None
 128     except ImportError:
 129         API = os.environ['QT_API'] = 'pyside2'
 130
 131 if API in PYSIDE2_API:
 132     try:
 133         from PySide2 import __version__ as PYSIDE_VERSION  # analysis:ignore
 134         from PySide2.QtCore import __version__ as QT_VERSION  # analysis:ignore
 135
 136         PYQT_VERSION = None
 137         PYQT5 = False
 138         PYSIDE2 = True
 139     except ImportError:
 140         API = os.environ['QT_API'] = 'pyqt'
 141
 142 if API in PYQT4_API:
 143     try:
 144         import sip
 145         try:
 146             sip.setapi('QString', 2)
 147             sip.setapi('QVariant', 2)
 148             sip.setapi('QDate', 2)
 149             sip.setapi('QDateTime', 2)
 150             sip.setapi('QTextStream', 2)
 151             sip.setapi('QTime', 2)
 152             sip.setapi('QUrl', 2)
 153         except (AttributeError, ValueError):
 154             # PyQt < v4.6
 155             pass
 156         from PyQt4.Qt import PYQT_VERSION_STR as PYQT_VERSION  # analysis:ignore
 157         from PyQt4.Qt import QT_VERSION_STR as QT_VERSION  # analysis:ignore
 158         PYSIDE_VERSION = None
 159         PYQT5 = False
 160         PYQT4 = True
 161     except ImportError:
 162         API = os.environ['QT_API'] = 'pyside'
 163     else:
 164         is_old_pyqt = PYQT_VERSION.startswith(('4.4', '4.5', '4.6', '4.7'))
 165         is_pyqt46 = PYQT_VERSION.startswith('4.6')
 166
 167 if API in PYSIDE_API:
 168     try:
 169         from PySide import __version__ as PYSIDE_VERSION  # analysis:ignore
 170         from PySide.QtCore import __version__ as QT_VERSION  # analysis:ignore
 171         PYQT_VERSION = None
 172         PYQT5 = PYSIDE2 = False
 173         PYSIDE = True
 174     except ImportError:
 175         raise PythonQtError('No Qt bindings could be found')
 176
 177 API_NAME = {'pyqt5': 'PyQt5', 'pyqt': 'PyQt4', 'pyqt4': 'PyQt4',
 178             'pyside': 'PySide', 'pyside2':'PySide2'}[API]
 179
 180 if PYQT4:
 181     import sip
 182     try:
 183         API_NAME += (" (API v{0})".format(sip.getapi('QString')))
 184     except AttributeError:
 185         pass