lib/mnit/assets.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2011-2013 Alexis Laferrière <alexis.laf@xymus.net>
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16
  17 # Manages all assets usable by an Mnit app
  18 module assets
  19
  20 import mnit_app
  21 import mnit::display
  22
  23 # General asset
  24 interface Asset
  25 end
  26
  27 # An String is an asset, returned from a text file
  28 redef class String
  29         super Asset
  30 end
  31
  32 # An Image is an asset
  33 redef interface Image
  34         super Asset
  35 end
  36
  37 redef class App
  38         # Load a genereal asset from file name
  39         # Will find the file within the assets/ directory
  40         # Crashes if file not found
  41         fun load_asset( id: String ): Asset
  42         do
  43                 var asset = try_loading_asset( id )
  44                 if asset == null then # error
  45                         print_error "asset <{id}> could not be loaded."
  46                         abort
  47                 else
  48                         return asset
  49                 end
  50         end
  51
  52         # Load an Image assets
  53         # Crashes if file not found or not an image
  54         fun load_image( id: String ): Image
  55         do
  56                 var asset = load_asset( id )
  57                 if asset isa Image then
  58                         return asset
  59                 else
  60                         print_error "asset <{id}> is not an image."
  61                         abort
  62                 end
  63         end
  64
  65         # Load an assets without error if not found
  66         fun try_loading_asset( id: String ): nullable Asset is abstract
  67 end