Open3D gui crashing after open tkinter filedialog

[ezrogoodman]

Describe the bug Open3D application based on example vis-gui.py crashes after usage of a tkinter askopenfilename file dialog.

To Reproduce Steps to reproduce the behavior:

1. run attached script and select File - Open
2. the app crashes without any error message no matter if a file was selected or the dialog was canceled

Environment (please complete the following information):

• Operating system: Windows 10 64-bit
• Python version: Python 3.8
• Open3D version: 0.14.1
• Is this remote workstation?: no
• How did you install Open3D?: pip

Additional context The reason for me to use a different file dialog than open3d.visualization.gui.FileDialog is the unability to select files from different that initial path's hard drive. I also tried easygui - it caused the same crashes. This might be the same issue as https://github.com/isl-org/Open3D/issues/1715 vis-gui-tk.zip

[dd-ff]

I had similar issues a while back and in order to fix it I had to run tkinter stuff in a separate thread, something like this:

import threading as thr
import tkinter as tk
from tkinter import filedialog
def AskFolder():
    a = tk.Tk()
    global save_path
    save_path = filedialog.askdirectory()
    a.destroy()

t = thr.Thread(target=AskFolder)
t.start()
t.join()
del t
global save_path #contains the requested path

Hope this helps.

[ezrogoodman]

Thanks for this tip. However, this solution works only once in an application run. On the second and every other call of the file dialog there is an error saying:

Exception in thread Thread-2:
Traceback (most recent call last):
  File "C:\ProgramData\Anaconda3\lib\threading.py", line 932, in _bootstrap_inner
    self.run()
  File "C:\ProgramData\Anaconda3\lib\threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "D:\Zivid storage\open3d\examples\python\gui\vis-gui-tk.py", line 651, in _open_file
    filePath = askopenfilename(title = "Select 3D data file",filetypes = (("Zivid or Polygon files", ".zdf .ply"),("Zivid files", ".zdf"),("Polygon files", ".ply"))) # Full pile will be returned as string
  File "C:\ProgramData\Anaconda3\lib\tkinter\filedialog.py", line 376, in askopenfilename
    return Open(**options).show()
  File "C:\ProgramData\Anaconda3\lib\tkinter\commondialog.py", line 40, in show
    w = Frame(self.master)
  File "C:\ProgramData\Anaconda3\lib\tkinter\__init__.py", line 3124, in __init__
    Widget.__init__(self, master, 'frame', cnf, {}, extra)
  File "C:\ProgramData\Anaconda3\lib\tkinter\__init__.py", line 2572, in __init__
    self.tk.call(
RuntimeError: main thread is not in main loop

I suppose there is some collision in accessing threads from tkinter and open3d window..

[dd-ff]

I currently don't get this error if I use the example code on Win10. The code:

t = thr.Thread(target=AskFolder)
t.start()
t.join()
del t
global save_path #contains the requested path

Is run in a new action (and callback function) added to the O3DVisualizer, while AskFolderis just a global method...

[ezrogoodman]

There's a difference: I'm not working with O3DVisualizer, my testing script is based on the vis-gui.py example code in which I added two methods to the AppWindow class: _on_menu_open_new() is called after File - Open selection, it starts new thread as you suggested containing _open_file() method which is basically the same as your AskFolder. You can try my code here: vis-gui-tk.zip Thanks for your cooperation :)

[dd-ff]

Upon seeing your code, you need to destroy Tk window each time you are done with it. This fixes your problem:

def _open_file(self):
        w = Tk()
        w.withdraw() # Added so Tk window doesn't appear on opening the dialog
        global filePath
        filePath = askopenfilename(title = "Select 3D data file",filetypes = (("Zivid or Polygon files", ".zdf .ply"),("Zivid files", ".zdf"),("Polygon files", ".ply"))) # Full pile will be returned as string
        # filePath = easygui.fileopenbox(title = "Select 3D data file",filetypes = [["*.zdf", "*.ply"],"*.zdf","*.ply"])
        if filePath:
            print(filePath)
        else:
            print("File dialog canceled")
        w.destroy()

[ezrogoodman]

That's it. Thank you very much!

[ssheorey]

Thanks @dd-ff for the help! Closing since this has been resolved. @ezrogoodman please reopen if you'd like any change in Open3D.