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Capture double tap of Ctrl in Hammerspoon
local alert = require("hs.alert")
local timer = require("hs.timer")
local eventtap = require("hs.eventtap")
local events = eventtap.event.types
local module = {}
-- Save this in your Hammerspoon configuration directiorn (~/.hammerspoon/)
-- You either override timeFrame and action here or after including this file from another, e.g.
--
-- ctrlDoublePress = require("ctrlDoublePress")
-- ctrlDoublePress.timeFrame = 2
-- ctrlDoublePress.action = function()
-- do something special
-- end
-- how quickly must the two single ctrl taps occur?
module.timeFrame = 1
-- what to do when the double tap of ctrl occurs
module.action = function()
alert("You double tapped ctrl!")
end
-- Synopsis:
-- what we're looking for is 4 events within a set time period and no intervening other key events:
-- flagsChanged with only ctrl = true
-- flagsChanged with all = false
-- flagsChanged with only ctrl = true
-- flagsChanged with all = false
local timeFirstControl, firstDown, secondDown = 0, false, false
-- verify that no keyboard flags are being pressed
local noFlags = function(ev)
local result = true
for k,v in pairs(ev:getFlags()) do
if v then
result = false
break
end
end
return result
end
-- verify that *only* the ctrl key flag is being pressed
local onlyCtrl = function(ev)
local result = ev:getFlags().ctrl
for k,v in pairs(ev:getFlags()) do
if k ~= "ctrl" and v then
result = false
break
end
end
return result
end
-- the actual workhorse
module.eventWatcher = eventtap.new({events.flagsChanged, events.keyDown}, function(ev)
-- if it's been too long; previous state doesn't matter
if (timer.secondsSinceEpoch() - timeFirstControl) > module.timeFrame then
timeFirstControl, firstDown, secondDown = 0, false, false
end
if ev:getType() == events.flagsChanged then
if noFlags(ev) and firstDown and secondDown then -- ctrl up and we've seen two, so do action
if module.action then module.action() end
timeFirstControl, firstDown, secondDown = 0, false, false
elseif onlyCtrl(ev) and not firstDown then -- ctrl down and it's a first
firstDown = true
timeFirstControl = timer.secondsSinceEpoch()
elseif onlyCtrl(ev) and firstDown then -- ctrl down and it's the second
secondDown = true
elseif not noFlags(ev) then -- otherwise reset and start over
timeFirstControl, firstDown, secondDown = 0, false, false
end
else -- it was a key press, so not a lone ctrl char -- we don't care about it
timeFirstControl, firstDown, secondDown = 0, false, false
end
return false
end):start()
return module
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