Escape Key Indicator

This script defines a custom status bar control that shows an indicator briefly after you press the escape key. This is useful if you are afflicted with a touch bar.

This script demonstrates a custom status bar component, a keyboard monitor, and using user-defined variables to make the keyboard monitor elicit a change in the status bar. It also demonstrates using asyncio tasks to perform an action after a delay, as well as how to cancel asyncio tasks.

After starting this script, navigate to Preferences > Profiles > Session. Turn on Status Bar Enabled and select Configure Status Bar. Drag the Esc Key Indicator component into the bottom section.

This script is a long-running daemon since it must continually update the status bar. As such, it should go in the AutoLaunch folder.

#!/usr/bin/env python3.7

import asyncio
import iterm2

counter = 0

async def main(connection):
    app = await iterm2.async_get_app(connection)
    tasks = {}

    component = iterm2.StatusBarComponent(
        short_description="Esc Key Indicator",
        detailed_description="Shows a visual indicator when the esc key is pressed",
        knobs=[],
        exemplar="[esc]",
        update_cadence=None,
        identifier="com.iterm2.escindicator")

    async def reset(session):
        await asyncio.sleep(2)
        await session.async_set_variable("user.showEscIndicator", False)

    async def keystroke_handler(keystroke):
        """This function is called every time a key is pressed."""
        if keystroke.keycode != iterm2.Keycode.ESCAPE:
            return

        # There might not be a current session, so there might be an exception
        # while trying to get it.
        try:
            session = app.current_terminal_window.current_tab.current_session
        except:
            return

        # The status bar coro will only be called when the variable changes,
        # so the value must be different each time. This only matters if you
        # press esc while reset() is still sleeping.
        global counter
        counter += 1
        await session.async_set_variable("user.showEscIndicator", counter)

    # The user variable `showEscIndicator` is used as a communications channel
    # between the keyboard monitor and the status bar component coro. Since it
    # may not always be defined (e.g., when a new session is created) it must be
    # labeled as optional with the trailing ? to prevent an exception.
    @iterm2.StatusBarRPC
    async def coro(
            knobs,
            show_indicator=iterm2.Reference("user.showEscIndicator?"),
            session_id=iterm2.Reference("id")):
        """This function gets called when showEscIndicator changes in any
        session."""
        if show_indicator:
            if session_id in tasks:
                tasks[session_id].cancel()
                del tasks[session_id]

            task = asyncio.create_task(reset(app.get_session_by_id(session_id)))
            tasks[session_id] = task
            return "[ESC]"
        else:
            return "     "

    # Register the status bar component.
    await component.async_register(connection, coro)

    # Monitor the keyboard
    async with iterm2.KeystrokeMonitor(connection) as mon:
        while True:
            keystroke = await mon.async_get()
            await keystroke_handler(keystroke)

iterm2.run_forever(main)

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