Any way to create a config for remap all cmd to ctrl?

[AlgusDark]

I want to remap my cmd to be ctrl in a terminal window only. Is there an easy way to do this with hammerspoon?
I haven't found a way and I'm new with the library.

This is something I was trying but with no success... but it works if I add a key. I want it to be any combination of modifiers and keys.

local modal = hs.hotkey.modal.new()

modal:bind({"cmd"}, 'WHAT_TO_PUT_HERE????', nil, function()
  hs.eventtap.keyStroke({"ctrl"}, 'WHAT_TO_PUT_HERE????')
end)

hs.window.filter.new('terminal')
    :subscribe(hs.window.filter.windowFocused,function()
        modal:enter()
    end)
    :subscribe(hs.window.filter.windowUnfocused,function()
        modal:exit()
    end)

Thanks.

[MuhammedZakir]

hs.eventtap is the correct one for this purpose.

E.g. #3190 (comment)
E.g.2. #1025 (comment)

Edit: I didn't post the any code because I haven't done this, and don't have a Mac atm to test the code. However, I can post one if you need one; can't guarantee whether it will work though.

[AlgusDark]

Thanks @MuhammedZakir , those link helped me to get a better idea on the API, but I'm still unable to came up with a working script 😅
It would be helpful if you could share a code and I can test/tweak it. I don't know how I could get the flags and just swap the cmd to ctrl 🤔

So far this is my code:

local log = hs.logger.new('init.lua', 'debug')

function table.removekey(table, key)
  local element = table[key]
  table[key] = nil
  return element
end

local function keyDownHandler(event)
  local flags = event:getFlags()
  local characters = event:getCharacters(true)
  local keyCode = event:getKeyCode()
  local type = event:getType()

  if flags['cmd'] then
    table.removekey(flags, 'cmd') -- remove cmd
    table.insert(flags, 'ctrl') -- add ctrl instead
    local evt = hs.eventtap.event.newEvent() -- create a new event with the same behaviour but swapped modifier
      :setType(type)
      :setKeyCode(keyCode)
      :setFlags(flags)
    
    return true, {evt} -- this doesn't work
  end
end

local keyDownEventListener = hs.eventtap.new({
		hs.eventtap.event.types.flagsChanged,
		hs.eventtap.event.types.keyDown
	}, keyDownHandler)

hs.window.filter.new('terminal')
  :subscribe(hs.window.filter.windowFocused,function()
    keyDownEventListener:start()
  end)
  :subscribe(hs.window.filter.windowUnfocused,function()
    keyDownEventListener:stop()
  end)

[MuhammedZakir]

Notes:

1. You will have to disable "secure keyboard entry" for key remapping to work.
2. Always save objects that you want to persist indefinitely in global variables or in local variables that are referenced by global variables. Otherwise, they will be garbage collected.
3. You may move this to a module to cleanup the function/variable names.

This should work:

local eventtap = hs.eventtap
local eventTypes = eventtap.event.types
local keycodes = hs.keycodes.map
local windowFilter = hs.window.filter


local function cmd2CtrlEventHandler(event)
  local flags = event:getFlags()
  local keycode = event:getKeyCode()

  if flags.cmd then
    flags.cmd = false
    flags.ctrl = true
  end

  if keycode == keycodes.cmd then
    keycode = keycodes.ctrl
  elseif keycode == keycodes.rightcmd then
    keycode = keycodes.rightctrl
  end

  event:setKeyCode(keycode)
  event:setFlags(flags)

  return false
end

local cmd2CtrlEventTapObj = eventtap.new({
  eventTypes.flagsChanged,
  eventTypes.keyDown,
  eventTypes.keyUp
}, cmd2CtrlEventHandler)

TerminalFocusFilter = windowFilter.new('Terminal'):subscribe({
  [windowFilter.windowFocused] = function() cmd2CtrlEventTapObj:start() end,
  [windowFilter.windowUnfocused] = function() cmd2CtrlEventTapObj:stop() end
})

[MuhammedZakir]

Thanks! Fixed those typos.

[AlgusDark]

I noticed that windowFilter makes the reload of my hammerspoon to randomly hang for some time. I'm wondering if there is another way. Something I did was to have the eventap globally by doing cmd2CtrlEventTapObj:start(). Inside of that I added a validation of if hs.application.frontmostApplication():name() ~= "Terminal" then return false end. I wonder if this is best, at least I haven't had problems when reloading my configuration now.

I'm asking that because I would like to rebind some buttons on slack... and I'm thinking on avoiding the windowfilter... maybe hs.application.watcher is a better choice?

[MuhammedZakir]

I noticed that windowFilter makes the reload of my hammerspoon to randomly hang for some time.

You should open an issue about this.

Something I did was to have the eventap globally by doing cmd2CtrlEventTapObj:start(). Inside of that I added a validation of if hs.application.frontmostApplication():name() ~= "Terminal" then return false end. I wonder if this is best, at least I haven't had problems when reloading my configuration now.

In this scenario, this seems fine, especially because you don't have any problems with this. :-)

I'm asking that because I would like to rebind some buttons on slack... and I'm thinking on avoiding the windowfilter... maybe hs.application.watcher is a better choice?

Hard to say without testing. I suggest you to test them and see which works better for you.

[MuhammedZakir]

Personally, I would do:

• if I want to remap many keys that may do different things depending on some condition, I would possibly do it like how you did above.
• if I want to remap keys or do some stuff for specific apps (and only has very few to no overlaps), then I would add a watcher for apps/windows, and do stuff using callbacks like how I did in this answer.
• if what I want to do has overlaps, then I use both.

This all assumes that the performance and stability of these are similiar, or have very little difference. Otherwise: run -> test -> fix / change code -> repeat.

[AlgusDark]

Perfect, thanks. I'll do some tests :)

[zhou13]

I created the hammerspoon-windows-mode using the method provided by @MuhammedZakir in case anyone needs a starting scripts to mimic keybinding in windows.