Turn hiding of Dock on or off by hammerspoon

[MirageTurtle]

Hi everyone,

I want to use hammerspoon to turn the hiding of Dock on or off in my script. I found maybe I could use hs.axuielement.applicationElement('Dock') get the Dock, but I didn't find anything about the hiding attribute. Because I'm not familiar with the OS X Accessibility API and the hs.axuielement, I want you to help me. Thank you very much!

Here's something I got:

require('pl.pretty').dump(hs.axuielement.applicationElement('Dock'):allAttributeValues())
2023-11-12 01:11:10: {
  AXChildren = {
    "hs.axuielement: AXList (0x7fa663d5a4f8)"
  },
  AXEnhancedUserInterface = false,
  AXRole = "AXApplication",
  AXRoleDescription = "application",
  AXTitle = "Dock"
}

And Good Night!

[MirageTurtle]

Now I find I can use hs.execute("defaults write com.apple.dock autohide -bool yes/no; killall Dock") to turn on or off. But I don't think it is elegant. So I still want to open this discussion, for how to do this work by hammerspoon-self.

[asmagill]

For items with popup menus, the menu items don't "exist", and thus don't have AXUIElement's we can access, unless the menu is showing (unlike the application menus, whose AXUIElement's always exist all the time). So, we have to take a few extra steps:

toggleDockHiding = function()
    local axuielement = require("hs.axuielement")
    local timer       = require("hs.timer")
    local minFloat    = require("hs.math").minFloat
    
    local dockElement = axuielement.applicationElement("com.apple.dock")
    local separator = nil
    -- the first child of the dock item is a list of the icons on display
    for _, child in ipairs(dockElement[1]) do
        if child.AXSubrole == "AXSeparatorDockItem" then
            separator = child
            break
        end
    end
    if separator then
        separator:doAXShowMenu()
        -- the children of the first child of `separator` will be the menu items, but it may take
        -- time to populate the list, so put the rest in a timer to give the application loop time to
        -- progress
        local menuTimer
        menuTimer = timer.doAfter(minFloat, function()
            menuTimer = nil -- make upvalue so not collected prematurely
            for _, menuitem in ipairs(separator[1]) do
                if menuitem.AXTitle:match("^Turn Hiding O") then
                    menuitem:doAXPress()
                    return
                end
            end
            -- if we're still here, then didn't find menu item
            separator:doAXShowMenu() -- closes menu
        end)
    end
end

[MirageTurtle]

Thank you for your comprehensive answer!

I find the method using hs.execute works well, and I may not change it recently.

Thank you again for letting me know better about AXUIElement!

[Rhys-T]

Be warned that killing the Dock like that may cause all your minimized windows to un-minimize themselves. (And possibly other side effects. The 'Dock' process is in charge of a surprising amount of non-Dock features, including Exposé/Spaces/Mission Control/whatever the current macOS is calling it.)

Another option that doesn't require killing the Dock or popping up menus is to use AppleScript:

-- Normally you can just use the builtin applescript function:
local applescript = hs.osascript.applescript
-- But as described in #1980, that function currently has a memory leak.
-- You might be better off running the AppleScript in a separate process like this instead:
local gsub = string.gsub
local function shellArg(x)
	return [[']] .. gsub(x, [[']], [['\'']]) .. [[']]
end
local function applescript(x)
	hs.execute('osascript -e '..shellArg(x))
end

-----------------------------------------------------------

local setDockAutohideScript = [[
	tell application "System Events"
		tell dock preferences
			set autohide to %s
		end tell
	end tell
]]
local function setDockAutohide(autohide)
	applescript(setDockAutohideScript:format(autohide and 'true' or 'false'))
end
local function toggleDockAutohide()
	applescript(setDockAutohideScript:format('not autohide'))
end

setDockAutohide(true)

---

Also, by default, there is a builtin keyboard shortcut to toggle Dock hiding: ⌘ Command-⌥ Option-D. (You can change it or turn it off by going to System Preferences → Keyboard → Shortcuts → Launchpad & Dock.) So if all you need is to be able to toggle Dock hiding from the keyboard, you can just use that. Or you can send that keyboard shortcut from Hammerspoon to toggle the Dock:

hs.eventtap.keyStroke({'command', 'option'}, 'd')

[rshev]

To complement @Rhys-T amazing answer, here is the full script to monitor if external display is connected and toggle dock autohide accordingly:

-- Normally you can just use the builtin applescript function:
local applescript = hs.osascript.applescript
-- But as described in #1980, that function currently has a memory leak.
-- You might be better off running the AppleScript in a separate process like this instead:
local gsub = string.gsub
local function shellArg(x)
	return [[']] .. gsub(x, [[']], [['\'']]) .. [[']]
end
local function applescript(x)
	hs.execute('osascript -e '..shellArg(x))
end

-----------------------------------------------------------

local setDockAutohideScript = [[
	tell application "System Events"
		tell dock preferences
			set autohide to %s
		end tell
	end tell
]]
local function setDockAutohide(autohide)
	applescript(setDockAutohideScript:format(autohide and 'true' or 'false'))
end
local function toggleDockAutohide()
	applescript(setDockAutohideScript:format('not autohide'))
end

-----------------------------------------------------------

function isExternalMonitorConnected()
    local screens = hs.screen.allScreens()
    local builtinScreen = hs.screen.primaryScreen() -- Usually the built-in screen is the primary one

    for _, screen in ipairs(screens) do
        if screen:id() ~= builtinScreen:id() then
            return true
        end
    end

    return false
end

local wasExternalConnected = isExternalMonitorConnected()

function monitorWatcherCallback()
    local isExternalConnected = isExternalMonitorConnected()

    if isExternalConnected and not wasExternalConnected then
    	print("👍 External monitor connected")
	setDockAutohide(false)
    elseif not isExternalConnected and wasExternalConnected then
    	print("👎 External monitor disconnected")
    	setDockAutohide(true)
    end

    wasExternalConnected = isExternalConnected
end

local screenWatcher = hs.screen.watcher.new(monitorWatcherCallback)
screenWatcher:start()