Hello list,
looking for a way to achieve inter-application drag and drop capabilities for
Tkinter
I came to look at the tkDnD extension for tcl/tk
(http://sourceforge.net/projects/tkdnd)
which adds native drag and drop support on windows and unix.
I couldn't find some approach to write a python interface for it anywhere
though, so I decided to try and write my own.
I currently got it at least partially working; before I do more detail work and
testing
I would like to ask the experts here, what you think about the general approach
I used.
(See the code below, a small demo included)
I could also use a helping hand on some of the tk related things, the way I
create the
command strings for tk doesn't look very good to me , but I cannot figure out
how to do it better.
Any feedback is highly appreciated.
Thanks in advance
Michael
############### file DnD.py
###############################################################
'''Python wrapper for the tkDnD tk extension.'''
class DnD:
def __init__(self, tkroot):
self._tkroot = tkroot
tkroot.tk.eval('package require tkdnd')
# make self an attribute of the parent window for easy access in child
classes
tkroot.dnd = self
def bindsource(self, widget, type=None, command=None, arguments=None,
priority=None):
'''Register widget as drag source; for details on type, command and
arguments, see bindtarget().
priority can be a value between 1 and 100, where 100 is the highest
available priority (default: 50).
If command is omitted, return the current binding for type; if both
type and command are omitted,
return a list of registered types for widget.'''
command = self._generate_callback(command, arguments)
tkcmd = self._generate_tkcommand('bindsource', widget, type, command,
priority)
res = self._tkroot.tk.eval(tkcmd)
if type == None:
res = res.split()
return res
def bindtarget(self, widget, type=None, sequence=None, command=None,
arguments=None, priority=None):
'''Register widget as drop target; type may be one of text/plain,
text/uri-list, text/plain;charset=UTF-8
(see the man page tkDND for details on other (platform specific) types);
sequence may be one of '<Drag>', '<DragEnter>', '<DragLeave>', '<Drop>'
or '<Ask>' ;
command is the callback associated with the specified event, argument
is an optional tuple of arguments
that will be passed to the callback; possible arguments include: %A %a
%b %C %c %D %d %L %m %T %t %W %X %x %Y %y
(see the tkDND man page for details); priority may be a value in the
range 1 to 100 ; if there are
bindings for different types, the one with the priority value will be
proceeded first (default: 50).
If command is omitted, return the current binding for type, where
sequence defaults to '<Drop>'.
If both type and command are omitted, return a list of registered types
for widget.'''
command = self._generate_callback(command, arguments)
tkcmd = self._generate_tkcommand('bindtarget', widget, type, sequence,
command, priority)
res = self._tkroot.tk.eval(tkcmd)
if type == None:
res = res.split()
return res
def clearsource(self, widget):
'''Unregister widget as drag source.'''
self._tkroot.tk.call('dnd', 'clearsource', widget)
def cleartarget(self, widget):
'''Unregister widget as drop target.'''
self._tkroot.tk.call('dnd', 'cleartarget', widget)
def drag(self, widget, actions=None, descriptions=None, cursorwindow=None,
command=None, arguments=None):
'''Initiate a drag operation with source widget.'''
command = self._generate_callback(command, arguments)
if actions:
if actions[1:]:
actions = '-actions {%s}' % ' '.join(actions)
else:
actions = '-actions %s' % actions[0]
if descriptions:
descriptions = ['{%s}'%i for i in descriptions]
descriptions = '{%s}' % ' '.join(descriptions)
if cursorwindow:
cursorwindow = '-cursorwindow %s' % cursorwindow
tkcmd = self._generate_tkcommand('drag', widget, actions, descriptions,
cursorwindow, command)
self._tkroot.tk.eval(tkcmd)
def _generate_callback(self, command, arguments):
'''Register command as tk callback with an optional list of
arguments.'''
cmd = None
if command:
cmd = self._tkroot._register(command)
if arguments:
cmd = '{%s %s}' % (cmd, ' '.join(arguments))
return cmd
def _generate_tkcommand(self, base, widget, *opts):
'''Create the command string that will be passed to tk.'''
tkcmd = 'dnd %s %s' % (base, widget)
for i in opts:
if i is not None:
tkcmd += ' %s' % i
return tkcmd
#############--demo code--########################################
def test():
import Tkinter
root = Tkinter.Tk()
dnd = DnD(root)
Tkinter.Label(root, text='Drop files from your file manager into the
listbox').pack(side='top')
l = Tkinter.Listbox(root)
l.pack(side='top', fill='both', expand=1)
root.update()# may be necessary on unix
# now make the listbox a drop target:
def drag(action, actions, type, win, X, Y, x, y, data):
return action
def drag_enter(action, actions, type, win, X, Y, x, y, data):
l.focus_force()
return action
def drop(action, actions, type, win, X, Y, x, y, data):
files = data.split()
for f in files:
l.insert('end', f)
dnd.bindtarget(l, 'text/uri-list', '<Drag>', drag, ('%A', '%a', '%T', '%W',
'%X', '%Y', '%x', '%y', '%D'))
dnd.bindtarget(l, 'text/uri-list', '<DragEnter>', drag_enter, ('%A', '%a',
'%T', '%W', '%X', '%Y', '%x', '%y', '%D'))
dnd.bindtarget(l, 'text/uri-list', '<Drop>', drop, ('%A', '%a', '%T', '%W',
'%X', '%Y', '%x', '%y','%D'))
root.mainloop()
if __name__ == '__main__':
test()
################ end of DnD.py
#######################################################
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