Hammerspoon config to send escape on short ctrl press

init.lua

ctrl_table = {
    sends_escape = true,
    last_mods = {}
}

control_key_timer = hs.timer.delayed.new(0.15, function()
    ctrl_table["send_escape"] = false
    -- log.i("timer fired")
    -- control_key_timer:stop()
end
)

last_mods = {}

control_handler = function(evt)
  local new_mods = evt:getFlags()
  if last_mods["ctrl"] == new_mods["ctrl"] then
      return false
  end
  if not last_mods["ctrl"] then
    -- log.i("control pressed")
    last_mods = new_mods
    ctrl_table["send_escape"] = true
    -- log.i("starting timer")
    control_key_timer:start()
  else
    -- log.i("contrtol released")
    -- log.i(ctrl_table["send_escape"])
    if ctrl_table["send_escape"] then
      -- log.i("send escape key...")
      hs.eventtap.keyStroke({}, "ESCAPE")
    end
    last_mods = new_mods
    control_key_timer:stop()
  end
  return false
end

control_tap = hs.eventtap.new({12}, control_handler)

control_tap:start()

Thanks so much for this! Works like a charm to get CAPSLOCK mapped to ESC and CTRL on Sierra!

Thanks for this, now to get my hyper back...

@arbelt I think it would be more clear if you change line 39 to be more explicit about the event flag you're targeting (it was the first thing I went digging for when reading through the code).

control_tap = hs.eventtap.new({ hs.eventtap.event.types.flagsChanged }, control_handler)

Without logging out hs.eventtap.event.types, it's unclear what event code 12 is.

Also, it doesn't appear to be breaking the logic since the priming on line 2 isn't necessary, but it's not named the same as the rest of the file. Line 2's sends_escape = true, has an "s" that the other references don't. It should be:

send_escape = true,

I'm finding this solution doesn't work with my tmux prefix chord unfortunately. I'll hack on it a bit and report back. If anyone else is in the same boat, let me know, and let me know what you've tried.

To get ready to play with it, I did some cleanup and simplification refactoring (original logic is still in tact, but with fewer variables). Feel free to have a look if you're using it as a jumping off point as well: https://gist.github.com/rjhilgefort/07ce5cdd3832083d7e94113d54372b1c

I have expanded on this script to avoid sending Escape when other keys are tapped while Control is held down. I’ve been running this for a few weeks now. Works great.

https://github.com/jasoncodes/dotfiles/blob/master/hammerspoon/control_escape.lua

Thank you arbelt and jasoncodes! This saved me from a lot of pain!

Instead of using hs.eventtap.keyStroke to emit an event, returning from the control_handler function with a table of events to post (KeyDown then KeyUp) makes the escape perform instantly on KeyUp. hs.eventtap.keyStroke feels slow for some reason, taking a fraction of a second before the actual stroke gets sent, drove me nuts.

control_handler = function(evt)
  local new_mods = evt:getFlags()
  if last_mods["ctrl"] == new_mods["ctrl"] then
    return false
  end
  if not last_mods["ctrl"] then
    last_mods = new_mods
    send_escape = true
    control_key_timer:start()
  else
    last_mods = new_mods
    control_key_timer:stop()
    if send_escape then
      return true, {
        hs.eventtap.event.newKeyEvent({}, 'escape', true),
        hs.eventtap.event.newKeyEvent({}, 'escape', false),
      }
    end
  end
  return false
end

Seems much faster!

@wezzynl Thank you for that comment. I also felt it a little unbearable sometimes to wait a fraction of a second for it to work. Also for some reason the escape key event would not be sent to emacs until I tried your solution.

In case anyone else comes upon this and finds the above code confusing or, like me, keeps getting a bug where you end up having to hit escape multiple times, I rewrote the above and added comments, clearer variable names, and fixed that bug. Gist located here: https://gist.github.com/zcmarine/f65182fe26b029900792fa0b59f09d7f

Definitely wouldn't have gotten that done without the above as an initial starting point though, so thanks a ton to arbelt and jasoncodes!

Hi everyone,
Is there a way to not have this run when a specific app is in focus? (for example: remote desktop, vmware, teamviewer etc.)
Many thanks!

@safecancel you can grab the current active application and use that to determine if the logic should run.

Thanks everyone. I've been using Karabiner-Elements only to remap caps lock to escape on tap and control on hold. With your solutions, I can use Hammerspoon instead (after changing caps lock to control in System Preferences) and drop Karabiner as a dependency.