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# (C) Copyright 2005-2023 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
""" Drag and drop utilities. """
from inspect import getfullargspec
import wx
class Clipboard(object):
""" The clipboard is used when dragging and dropping Python objects. """
# fixme: This obviously only works within a single process!
pass
clipboard = Clipboard()
clipboard.drop_source = None
clipboard.source = None
clipboard.data = None
class FileDropSource(wx.DropSource):
""" Represents a draggable file.
"""
def __init__(self, source, files):
""" Initializes the object.
"""
self.handler = None
self.allow_move = True
# Put the data to be dragged on the clipboard:
clipboard.data = files
clipboard.source = source
clipboard.drop_source = self
data_object = wx.FileDataObject()
if isinstance(files, str):
files = [files]
for file in files:
data_object.AddFile(file)
# Create the drop source and begin the drag and drop operation:
super().__init__(source)
self.SetData(data_object)
self.result = self.DoDragDrop(True)
def on_dropped(self, drag_result):
""" Called when the data has been dropped. """
class FileDropTarget(wx.FileDropTarget):
""" Drop target for files. """
def __init__(self, handler):
""" Constructor. """
# Base-class constructor.
wx.FileDropTarget.__init__(self)
self.handler = handler
def OnDropFiles(self, x, y, filenames):
""" Called when the files have been dropped. """
for filename in filenames:
self.handler(x, y, filename)
# Return True to accept the data, False to veto it.
return True
# The data format for Python objects!
PythonObject = wx.DataFormat("PythonObject")
class PythonDropSource(wx.DropSource):
""" Drop source for Python objects. """
def __init__(self, source, data, handler=None, allow_move=True):
""" Creates a new drop source.
A drop source should be created for *every* drag operation.
If allow_move is False then the operation will default to
a copy and only copy operations will be allowed.
"""
# The handler can either be a function that will be called when
# the data has been dropped onto the target, or an instance that
# supports the 'on_dropped' method.
self.handler = handler
self.allow_move = allow_move
# Put the data to be dragged on the clipboard.
clipboard.data = data
clipboard.source = source
clipboard.drop_source = self
# Create our own data format and use it in a custom data object.
data_object = wx.CustomDataObject(PythonObject)
data_object.SetData(b"dummy")
# And finally, create the drop source and begin the drag
# and drop opperation.
wx.DropSource.__init__(self, source)
self.SetData(data_object)
if allow_move:
flags = wx.Drag_DefaultMove | wx.Drag_AllowMove
else:
flags = wx.Drag_CopyOnly
self.result = self.DoDragDrop(flags)
def on_dropped(self, drag_result):
""" Called when the data has been dropped. """
if self.handler is not None:
if hasattr(self.handler, "on_dropped"):
# For backward compatibility we accept handler functions
# with either 1 or 3 args, including self. If there are
# 3 args then we pass the data and the drag_result.
args = getfullargspec(self.handler.on_dropped)[0]
if len(args) == 3:
self.handler.on_dropped(clipboard.data, drag_result)
else:
self.handler.on_dropped()
else:
# print self.handler
# In this case we assume handler is a function.
# For backward compatibility we accept handler functions
# with either 0 or 2 args. If there are 2 args then
# we pass the data and drag_result
args = getfullargspec(self.handler)[0]
if len(args) == 2:
self.handler(clipboard.data, drag_result)
else:
self.handler()
class PythonDropTarget(wx.DropTarget):
""" Drop target for Python objects. """
def __init__(self, handler):
""" Constructor
The handler can be either a function that will be called when
*any* data is dropped onto the target, or an instance that supports
the 'wx_drag_over' and 'wx_dropped_on' methods. The latter case
allows the target to veto the drop.
"""
# Base-class constructor.
super().__init__()
# The handler can either be a function that will be called when
# any data is dropped onto the target, or an instance that supports
# the 'wx_drag_over' and 'wx_dropped_on' methods. The latter case
# allows the target to veto the drop.
self.handler = handler
# Specify the type of data we will accept.
self.data_object = wx.DataObjectComposite()
self.data = wx.CustomDataObject(PythonObject)
self.data_object.Add(self.data, preferred=True)
self.file_data = wx.FileDataObject()
self.data_object.Add(self.file_data)
self.SetDataObject(self.data_object)
def OnData(self, x, y, default_drag_result):
""" Called when OnDrop returns True. """
# First, if we have a source in the clipboard and the source
# doesn't allow moves then change the default to copy
if (
clipboard.drop_source is not None
and not clipboard.drop_source.allow_move
):
default_drag_result = wx.DragCopy
elif clipboard.drop_source is None:
# This means we might be receiving a file; try to import
# the right packages to nicely handle a file drop. If those
# packages can't be imported, then just pass through.
if self.GetData():
try:
from apptools.io import File
from apptools.naming.api import Binding
names = self.file_data.GetFilenames()
files = []
bindings = []
for name in names:
f = File(name)
files.append(f)
bindings.append(Binding(name=name, obj=f))
clipboard.data = files
clipboard.node = bindings
except ImportError:
pass
# Pass the object on the clipboard it to the handler.
#
# fixme: We allow 'wx_dropped_on' and 'on_drop' because both Dave
# and Martin want different things! Unify!
if hasattr(self.handler, "wx_dropped_on"):
drag_result = self.handler.wx_dropped_on(
x, y, clipboard.data, default_drag_result
)
elif hasattr(self.handler, "on_drop"):
drag_result = self.handler.on_drop(
x, y, clipboard.data, default_drag_result
)
else:
self.handler(x, y, clipboard.data)
drag_result = default_drag_result
# Let the source of the drag/drop know that the operation is complete.
drop_source = clipboard.drop_source
if drop_source is not None:
drop_source.on_dropped(drag_result)
# Clean out the drop source!
clipboard.drop_source = None
# The return value tells the source what to do with the original data
# (move, copy, etc.). In this case we just return the suggested value
# given to us.
return default_drag_result
# Some virtual methods that track the progress of the drag.
def OnDragOver(self, x, y, default_drag_result):
""" Called when a data object is being dragged over the target. """
# First, if we have a source in the clipboard and the source
# doesn't allow moves then change the default to copy
data = clipboard.data
if clipboard.drop_source is None:
if not hasattr(self.handler, "wx_drag_any"):
# this is probably a file being dragged in, so just return
return default_drag_result
data = None
elif not clipboard.drop_source.allow_move:
default_drag_result = wx.DragCopy
# The value returned here tells the source what kind of visual feedback
# to give. For example, if wxDragCopy is returned then only the copy
# cursor will be shown, even if the source allows moves. You can use
# the passed in (x,y) to determine what kind of feedback to give.
# In this case we return the suggested value which is based on whether
# the Ctrl key is pressed.
#
# fixme: We allow 'wx_drag_over' and 'on_drag_over' because both Dave
# and Martin want different things! Unify!
if hasattr(self.handler, "wx_drag_any"):
drag_result = self.handler.wx_drag_any(
x, y, data, default_drag_result
)
elif hasattr(self.handler, "wx_drag_over"):
drag_result = self.handler.wx_drag_over(
x, y, data, default_drag_result
)
elif hasattr(self.handler, "on_drag_over"):
drag_result = self.handler.on_drag_over(
x, y, data, default_drag_result
)
else:
drag_result = default_drag_result
return drag_result
def OnLeave(self):
""" Called when the mouse leaves the drop target. """
if hasattr(self.handler, "wx_drag_leave"):
self.handler.wx_drag_leave(clipboard.data)
def OnDrop(self, x, y):
""" Called when the user drops a data object on the target.
Return 'False' to veto the operation.
"""
return True
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