tabakrolletjie/loader.py

   1 """ Utilities for loading resource files. """
   2
   3 import json
   4 import os
   5
   6 import pygame.image
   7 import pygame.display
   8
   9 from .constants import DEBUG
  10
  11
  12 class Loader(object):
  13     """ Load data files from beneath a prefix. """
  14
  15     def __init__(self, prefix):
  16         self._prefix = prefix
  17         self._cache = {}
  18
  19     def full_path(self, *parts):
  20         path = "/".join(parts)
  21         rel_path = os.path.join(*path.split("/"))
  22         abs_path = os.path.join(self._prefix, rel_path)
  23         if DEBUG:
  24             print abs_path
  25         return abs_path
  26
  27     def open_file(self, *parts):
  28         return file(self.full_path(*parts), "rb")
  29
  30     def load_station(self, *parts):
  31         with self.open_file("stations", *parts) as f:
  32             return json.load(f)
  33
  34     def load_image(self, *parts):
  35         """Return a pygame surface of the requested image."""
  36         fn = self.full_path("images", *parts)
  37         img = self._cache.get(fn, None)
  38         if img is None:
  39             img = pygame.image.load(fn)
  40             # We assume pygame.display has been initialised
  41             # Fix this if that changes
  42             img.convert_alpha(pygame.display.get_surface())
  43             self._cache[fn] = img
  44         return img
  45
  46
  47 _DATA_PREFIX = os.path.abspath(
  48     os.path.join(os.path.dirname(__file__), "..", "data"))
  49
  50 loader = Loader(_DATA_PREFIX)