Simple Listener directive for firing on keyboard state change ('onKeyboardShow', 'onKeyboardHide') in cordova angular apps (with fixed orientation)

keyboardListener.coffee

'use strict'

angular.module('app')
  .directive 'keyboardListener', [ '$rootScope', ($rootScope) ->

    restrict: 'A'

    link: ($scope, $element, attrs) ->

      _height = undefined

      _update = () ->

        currentHeight = angular.element($element)[0].offsetHeight

        if _height?

          if currentHeight < _height
            $rootScope.$broadcast 'onKeyboardShow'
          else if currentHeight > _height
            $rootScope.$broadcast 'onKeyboardHide'

        _height = currentHeight

      # window resize event

      angular.element(window).bind 'resize', () ->

        $rootScope.$apply () ->
          _update()

      # init

      _update()

  ]