events.lua

   1 local EventPrototype = {}
   2
   3 function EventPrototype:preventDefault()
   4         self.defaultPrevented = true
   5 end
   6
   7 function Event(type, data)
   8         return setmetatable({
   9                 type = type,
  10                 data = data,
  11                 defaultPrevented = false,
  12                 timeStamp = lua_async.clock(),
  13         }, {__index = EventPrototype})
  14 end
  15
  16 local EventTargetPrototype = {}
  17
  18 function EventTargetPrototype:dispatchEvent(event)
  19         event.target = self
  20
  21         local callback = self["on" .. event.type]
  22
  23         if callback then
  24                 callback(event)
  25         end
  26
  27         local listeners = self.__eventListeners[event.type]
  28
  29         if listeners then
  30                 for i, callback in ipairs(listeners) do
  31                         callback(event)
  32                 end
  33         end
  34
  35         return not event.defaultPrevented
  36 end
  37
  38 function EventTargetPrototype:addEventListener(type, callback)
  39         local listeners = self.__eventListeners[type] or {}
  40         table.insert(listeners, callback)
  41         self.__eventListeners[type] = listeners
  42 end
  43
  44 function EventTargetPrototype:removeEventListener(type, callback)
  45         local listeners = self.__eventListeners[type]
  46
  47         if listeners then
  48                 for k, v in pairs(listeners) do
  49                         if v == callback then
  50                                 table.remove(listeners, k)
  51                                 break
  52                         end
  53                 end
  54         end
  55 end
  56
  57 function EventTarget()
  58         return setmetatable({
  59                 __eventListeners = {},
  60         }, {__index = EventTargetPrototype})
  61 end