Drag and drop in wxPython
last modified January 10, 2023
In computer graphical user interfaces, drag-and-drop is the action of (or support for the action of) clicking on a virtual object and dragging it to a different location or onto another virtual object. In general, it can be used to invoke many kinds of actions, or create various types of associations between two abstract objects.
Drag and drop operation enables you to do complex things intuitively.
In drag and drop operations we drag some data from a data source to a data target. So we must have:
- Some data
- A data source
- A data target
In wxPython we have two predefined data targets: wx.TextDropTarget
and wx.FileDropTarget.
wx.TextDropTarget
wx.TextDropTarget is a predefined drop target for dealing with
text data.
#!/usr/bin/env python
"""
ZetCode wxPython tutorial
In this example, we drag and drop text data.
author: Jan Bodnar
website: www.zetcode.com
last modified: July 2020
"""
from pathlib import Path
import os
import wx
class MyTextDropTarget(wx.TextDropTarget):
def __init__(self, object):
wx.TextDropTarget.__init__(self)
self.object = object
def OnDropText(self, x, y, data):
self.object.InsertItem(0, data)
return True
class Example(wx.Frame):
def __init__(self, *args, **kw):
super(Example, self).__init__(*args, **kw)
self.InitUI()
def InitUI(self):
splitter1 = wx.SplitterWindow(self, style=wx.SP_3D)
splitter2 = wx.SplitterWindow(splitter1, style=wx.SP_3D)
home_dir = str(Path.home())
self.dirWid = wx.GenericDirCtrl(splitter1, dir=home_dir,
style=wx.DIRCTRL_DIR_ONLY)
self.lc1 = wx.ListCtrl(splitter2, style=wx.LC_LIST)
self.lc2 = wx.ListCtrl(splitter2, style=wx.LC_LIST)
dt = MyTextDropTarget(self.lc2)
self.lc2.SetDropTarget(dt)
self.Bind(wx.EVT_LIST_BEGIN_DRAG, self.OnDragInit, id=self.lc1.GetId())
tree = self.dirWid.GetTreeCtrl()
splitter2.SplitHorizontally(self.lc1, self.lc2, 150)
splitter1.SplitVertically(self.dirWid, splitter2, 200)
self.Bind(wx.EVT_TREE_SEL_CHANGED, self.OnSelect, id=tree.GetId())
self.OnSelect(0)
self.SetTitle('Drag and drop text')
self.Centre()
def OnSelect(self, event):
list = os.listdir(self.dirWid.GetPath())
self.lc1.ClearAll()
self.lc2.ClearAll()
for i in range(len(list)):
if list[i][0] != '.':
self.lc1.InsertItem(0, list[i])
def OnDragInit(self, event):
text = self.lc1.GetItemText(event.GetIndex())
tdo = wx.TextDataObject(text)
tds = wx.DropSource(self.lc1)
tds.SetData(tdo)
tds.DoDragDrop(True)
def main():
app = wx.App()
ex = Example(None)
ex.Show()
app.MainLoop()
if __name__ == '__main__':
main()
In the example, we show a file system in a wx.GenericDirCtrl.
The contents of a selected directory are shown in the upper right list control.
The file names can be drag and dropped into the bottom-right list control.
def OnDropText(self, x, y, data):
self.object.InsertItem(0, data)
return True
When we drop text data onto the target, the data is inserted into the list
control with InsertItem() method.
dt = MyTextDropTarget(self.lc2) self.lc2.SetDropTarget(dt)
A drop target is created. We set the drop target to the second list control
with SetDropTarget() method.
self.Bind(wx.EVT_LIST_BEGIN_DRAG, self.OnDragInit, id=self.lc1.GetId())
When the drag operation begins, the OnDragInit() method is invoked.
def OnDragInit(self, event):
text = self.lc1.GetItemText(event.GetIndex())
tdo = wx.TextDataObject(text)
tds = wx.DropSource(self.lc1)
...
In the OnDragInit() method, we create a wx.TextDataObject,
which contains our text data. A drop source is created from the first list control.
tds.SetData(tdo) tds.DoDragDrop(True)
We set data to the drop source with SetData() and initiate
the drag drop operation with DoDragDrop().
wx.FileDropTarget
wx.FileDropTarget is a drop target which accepts files, which are
dragged from a file manager.
#!/usr/bin/env python
"""
ZetCode wxPython tutorial
In this example, we drag and drop files.
author: Jan Bodnar
website: www.zetcode.com
last modified: July 2020
"""
import wx
class FileDrop(wx.FileDropTarget):
def __init__(self, window):
wx.FileDropTarget.__init__(self)
self.window = window
def OnDropFiles(self, x, y, filenames):
for name in filenames:
try:
file = open(name, 'r')
text = file.read()
self.window.WriteText(text)
except IOError as error:
msg = "Error opening file\n {}".format(str(error))
dlg = wx.MessageDialog(None, msg)
dlg.ShowModal()
return False
except UnicodeDecodeError as error:
msg = "Cannot open non ascii files\n {}".format(str(error))
dlg = wx.MessageDialog(None, msg)
dlg.ShowModal()
return False
finally:
file.close()
return True
class Example(wx.Frame):
def __init__(self, *args, **kw):
super(Example, self).__init__(*args, **kw)
self.InitUI()
def InitUI(self):
self.text = wx.TextCtrl(self, style = wx.TE_MULTILINE)
dt = FileDrop(self.text)
self.text.SetDropTarget(dt)
self.SetTitle('File drag and drop')
self.Centre()
def main():
app = wx.App()
ex = Example(None)
ex.Show()
app.MainLoop()
if __name__ == '__main__':
main()
The example creates a simple wx.TextCtrl. We can drag text
files to the control from a file manager.
def OnDropFiles(self, x, y, filenames):
for name in filenames:
...
We can drag and drop multiple file at once.
try:
file = open(name, 'r')
text = file.read()
self.window.WriteText(text)
We open the file in the read-only mode, get its contents and write the contents into the text control window.
except IOError as error:
msg = "Error opening file\n {}".format(str(error))
dlg = wx.MessageDialog(None, msg)
dlg.ShowModal()
return False
In case of an input/output error, we show a message dialog and terminate the operation.
self.text = wx.TextCtrl(self, style = wx.TE_MULTILINE) dt = FileDrop(self.text) self.text.SetDropTarget(dt)
The wx.TextCtrl is the drop target.
In this chapter we worked with drag and drop operations in wxPython.