Add hammerspoon. Almost usable now...

wm/hammerspoon/ctrlDoubleTap.lua

@@ -0,0 +1,70 @@
+local timer = require("hs.timer")
+local eventtap = require("hs.eventtap")
+
+local events = eventtap.event.types
+
+local module = {}
+
+module.timeFrame = 1
+
+module.action = function()
+  hs.alert("You double tapped ctrl!")
+end
+
+local timeFirstControl = 0
+local firstDown = false
+local secondDown = false
+
+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
+
+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
+
+local reset = function()
+  timeFirstControl = 0
+  firstDown = false
+  secondDown = false
+end
+
+module.eventWatcher = eventtap.new({events.flagsChanged, events.keyDown}, function(ev)
+  if(timer.secondsSinceEpoch() - timeFirstControl) > module.timeFrame then
+    reset()
+  end
+
+  if ev:getType() == events.flagsChanged then
+    if noFlags(ev) and firstDown and secondDown then
+      if module.action then module.action() end
+      reset()
+    elseif onlyCtrl(ev) and not firstDown then
+      firstDown = true
+      timeFirstControl = timer.secondsSinceEpoch()
+    elseif onlyCtrl(ev) and firstDown then
+      secondDown = true
+    elseif not noFlags(ev) then
+      reset()
+    end
+  else
+    reset()
+  end
+  return false
+end):start()
+
+return module
+