pyqtgraph/Qt.py

## Do all Qt imports from here to allow easier PyQt / PySide compatibility
import sys

## Automatically determine whether to use PyQt or PySide. 
## This is done by first checking to see whether one of the libraries
## is already imported. If not, then attempt to import PyQt4, then PySide.
if 'PyQt4' in sys.modules:
    USE_PYSIDE = False
elif 'PySide' in sys.modules:
    USE_PYSIDE = True
else:
    try:
        import PyQt4
        USE_PYSIDE = False
    except ImportError:
        try:
            import Pyside
            USE_PYSIDE = True
        except ImportError:
            raise Exception("PyQtGraph requires either PyQt4 or PySide; neither package could be imported.")

if USE_PYSIDE:
    from PySide import QtGui, QtCore, QtOpenGL, QtSvg
    import PySide
    VERSION_INFO = 'PySide ' + PySide.__version__
else:
    from PyQt4 import QtGui, QtCore
    try:
        from PyQt4 import QtSvg
    except ImportError:
        pass
    try:
        from PyQt4 import QtOpenGL
    except ImportError:
        pass

    QtCore.Signal = QtCore.pyqtSignal
    VERSION_INFO = 'PyQt4 ' + QtCore.PYQT_VERSION_STR + ' Qt ' + QtCore.QT_VERSION_STR