lib/gamnit/keys.nit

   1 # This file is part of NIT (http://www.nitlanguage.org).
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #        http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 # Simple service keeping track of which keys are currently pressed
  16 #
  17 # This service revolves around `app.pressed_keys`, a `Set` of the names of currently pressed keys.
  18 # As a `Set`, `app.pressed_keys` can be iterated and queried with `has`.
  19 #
  20 # Limitations: The keys names are platform dependent.
  21 module keys
  22
  23 import mnit::input
  24 import gamnit
  25
  26 redef class App
  27         # Currently pressed keys
  28         var pressed_keys = new Set[String] is lazy
  29
  30         # Register `event` to update `app.pressed_keys`
  31         private fun register_key_event(event: KeyEvent)
  32         do
  33                 var key = event.name
  34                 if event.is_down then
  35                         app.pressed_keys.add key
  36                 else if app.pressed_keys.has(key) then
  37                         app.pressed_keys.remove key
  38                 end
  39         end
  40
  41         redef fun accept_event(event)
  42         do
  43                 if event isa KeyEvent then register_key_event event
  44
  45                 return super
  46         end
  47 end