tkinter-async-loop.py

import asyncio
import logging
import tkinter as tk
from tkinter import messagebox
from async_tkinter_loop import async_handler, get_event_loop

root = tk.Tk()

class AsyncTk():
    def __init__(self,root):
        self.root = root
        self.recurse_cnt = 0

    def _run_async_cb(self):
        # blocking call to loop
        self.recurse_cnt += 1
        if self.recurse_cnt > 1:
            print("Warning: recursion detected")
        self.loop.create_task(self._stop_loop_later())
        # run loop blocking mode untill stop in _stop_loop_later is called
        self.loop.run_forever()
        #self._register_async_cb_now()
        self._register_async_cb_later()
        self.recurse_cnt -= 1

    def _register_async_cb_later(self):
        self.root.after(1,self._run_async_cb)

    def _register_async_cb_now(self):
        self.root.after_idle(self._run_async_cb)

    async def _stop_loop_later(self):
        await asyncio.sleep(0.005)
        self.loop.stop()
    
    def start(self):
        self._register_async_cb_later()

    @property
    def loop(self):
        return get_event_loop()

async def async_dispatch(root,cb):
    # call sync_call (cb) "async" (cb must be one of blocking calls from tkinter -  MessageBox, FileDialog, etc.)
    queue = asyncio.Queue(maxsize=1)
    def sync_call():
        r = cb()
        async def push_result():
            await queue.put(r)    
        get_event_loop().create_task(push_result())
    root.after_idle(sync_call)
    q = await queue.get()
    return q



@async_handler
async def loop():
    while True:
        counter.set(counter.get() + 1)
        await asyncio.sleep(0.01)

@async_handler
async def show_message():
    # messagebox is "blocking" so we need to call as blocking (no async function / cb)
    # 
    # or use async_dispatch
    r = await async_dispatch(root,lambda: messagebox.showinfo("Info", "Some info"))
    logging.debug(f"messagebox result: {r}")

logging.basicConfig(level=logging.DEBUG)

counter = tk.IntVar()
tk.Label(root, textvariable=counter).pack()

tk.Button(root, text="Start counter", command=loop).pack()
tk.Button(root, text="Show message", command=show_message).pack()

as_tk = AsyncTk(root)
as_tk.start()

#async_mainloop(root)
root.mainloop()