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#------------------------------------------------------------------------------
# Copyright (c) 2007, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD license.
# However, when used with the GPL version of PyQt the additional terms described in the PyQt GPL exception also apply
#
# Author: Riverbank Computing Limited
#------------------------------------------------------------------------------
""" Implements a wrapper around the PyQt clipboard that handles Python objects
using pickle.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from cPickle import dumps, load, loads, PickleError
from cStringIO import StringIO
import warnings
from pyface.qt import QtCore, QtGui
from traits.api import HasTraits, Instance, Property
#-------------------------------------------------------------------------------
# 'PyMimeData' class:
#-------------------------------------------------------------------------------
class PyMimeData(QtCore.QMimeData):
""" The PyMimeData wraps a Python instance as MIME data.
"""
# The MIME type for instances.
MIME_TYPE = 'application/x-ets-qt4-instance'
NOPICKLE_MIME_TYPE = 'application/x-ets-qt4-instance-no-pickle'
def __init__(self, data=None, pickle=True):
""" Initialise the instance.
"""
QtCore.QMimeData.__init__(self)
# Keep a local reference to be returned if possible.
self._local_instance = data
if pickle:
if data is not None:
# We may not be able to pickle the data.
try:
pdata = dumps(data)
# This format (as opposed to using a single sequence) allows
# the type to be extracted without unpickling the data.
self.setData(self.MIME_TYPE, dumps(data.__class__) + pdata)
except (PickleError, TypeError):
# if pickle fails, still try to create a draggable
warnings.warn(("Could not pickle dragged object %s, " +
"using %s mimetype instead") % (repr(data),
self.NOPICKLE_MIME_TYPE), RuntimeWarning)
self.setData(self.NOPICKLE_MIME_TYPE, str(id(data)))
else:
self.setData(self.NOPICKLE_MIME_TYPE, str(id(data)))
@classmethod
def coerce(cls, md):
""" Wrap a QMimeData or a python object to a PyMimeData.
"""
# See if the data is already of the right type. If it is then we know
# we are in the same process.
if isinstance(md, cls):
return md
if isinstance(md, PyMimeData):
# if it is a PyMimeData, migrate all its data, subclasses should
# override this method if it doesn't do thgs correctly for them
data = md.instance()
nmd = cls()
nmd._local_instance = data
for format in md.formats():
nmd.setData(format, md.data(format))
elif isinstance(md, QtCore.QMimeData):
# if it is a QMimeData, migrate all its data
nmd = cls()
for format in md.formats():
nmd.setData(format, md.data(format))
else:
# by default, try to pickle the coerced object
pickle = True
# See if the data is a list, if so check for any items which are
# themselves of the right type. If so, extract the instance and
# track whether we should pickle.
# XXX lists should suffice for now, but may want other containers
if isinstance(md, list):
pickle = not any(item.hasFormat(cls.NOPICKLE_MIME_TYPE)
for item in md if isinstance(item, QtCore.QMimeData))
md = [item.instance() if isinstance(item, PyMimeData) else item
for item in md]
# Arbitrary python object, wrap it into PyMimeData
nmd = cls(md, pickle)
return nmd
def instance(self):
""" Return the instance.
"""
if self._local_instance is not None:
return self._local_instance
if not self.hasFormat(self.MIME_TYPE):
# We have no pickled python data defined.
return None
io = StringIO(str(self.data(self.MIME_TYPE)))
try:
# Skip the type.
load(io)
# Recreate the instance.
return load(io)
except PickleError:
pass
return None
def instanceType(self):
""" Return the type of the instance.
"""
if self._local_instance is not None:
return self._local_instance.__class__
try:
if self.hasFormat(self.MIME_TYPE):
return loads(str(self.data(self.MIME_TYPE)))
except PickleError:
pass
return None
def localPaths(self):
""" The list of local paths from url list, if any.
"""
ret = []
for url in self.urls():
if url.scheme() == 'file':
ret.append(url.toLocalFile())
return ret
#-------------------------------------------------------------------------------
# '_Clipboard' class:
#-------------------------------------------------------------------------------
class _Clipboard(HasTraits):
""" The _Clipboard class provides a wrapper around the PyQt clipboard.
"""
#---------------------------------------------------------------------------
# Trait definitions:
#---------------------------------------------------------------------------
# The instance on the clipboard (if any).
instance = Property
# Set if the clipboard contains an instance.
has_instance = Property
# The type of the instance on the clipboard (if any).
instance_type = Property
# The application clipboard.
clipboard = Instance(QtGui.QClipboard)
#---------------------------------------------------------------------------
# Instance property methods:
#---------------------------------------------------------------------------
def _get_instance(self):
""" The instance getter.
"""
md = PyMimeData.coerce(self.clipboard.mimeData())
if md is None:
return None
return md.instance()
def _set_instance(self, data):
""" The instance setter.
"""
self.clipboard.setMimeData(PyMimeData(data))
def _get_has_instance(self):
""" The has_instance getter.
"""
return self.clipboard.mimeData().hasFormat(PyMimeData.MIME_TYPE)
def _get_instance_type(self):
""" The instance_type getter.
"""
md = PyMimeData.coerce(self.clipboard.mimeData())
if md is None:
return None
return md.instanceType()
#---------------------------------------------------------------------------
# Other trait handlers:
#---------------------------------------------------------------------------
def _clipboard_default(self):
""" Initialise the clipboard.
"""
return QtGui.QApplication.clipboard()
#-------------------------------------------------------------------------------
# The singleton clipboard instance.
#-------------------------------------------------------------------------------
clipboard = _Clipboard()
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