Tray icon does not appear on Mac

[qstokkink]

The pystray tray icon does not appear on Mac. This happens both when running from source and when running from the build. I uncovered that the following line is to blame:

tribler/src/run_tribler.py

Line 197 in 35cc11e

threading.Thread(target=icon.run).start()

Only on Mac, icon.run() cannot be run on anything other than the main thread.

BUT if you do run icon.run() on the main thread, it blocks the main thread until the application exits. The run_detached function exists but this doesn't work without extra effort. In particular, we need to run an event loop or, rather, something that consumes and runs events on the main Python thread.

I made a proof-of-concept of an asyncio-compatible consuming "event loop" (the meat is in runEventLoop and main is essentially our run_tribler.py with two changed lines):

import asyncio
import sys
from asyncio import run, sleep

import pystray
from PIL import Image

from AppKit import NSApp, NSEventMaskAny
from Foundation import NSDate, NSDefaultRunLoopMode

import tribler

async def runEventLoop():
    while True:
        event = NSApp().nextEventMatchingMask_untilDate_inMode_dequeue_(NSEventMaskAny, NSDate.now(), NSDefaultRunLoopMode, True)
        NSApp().sendEvent_(event)
        await sleep(0)


async def main():
    image_path = tribler.get_webui_root() / "public" / "tribler.png"
    image = Image.open(image_path.absolute().resolve())
    menu = (pystray.MenuItem('Open', lambda: print("open")),
            pystray.MenuItem('Quit', lambda: sys.exit(0)))
    icon: pystray._darwin.Icon = pystray.Icon("Tribler", icon=image, title="Tribler", menu=menu)

    icon.run_detached(None)  # <---
    asyncio.ensure_future(runEventLoop())  # <---

    for i in range(10):
        print(10-i, "...")
        await asyncio.sleep(1)
    icon.stop()


if __name__ == "__main__":
    run(main())

We may want to beautify this a bit.