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comparison gamelib/imagecache.py @ 41:6055a8a8678d

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Add image cache (with support for modified versions of an image).
author Simon Cross <hodgestar@gmail.com>
date Mon, 31 Aug 2009 16:47:54 +0000
parents
children f20dd3dcb118
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40:678421bd58ee 41:6055a8a8678d
1 """Central image cache to avoid loading images multiple times."""
2
3 import pygame
4 import data
5
6 class ImageCache(object):
7 """Create an image cache with a list of modifiers."""
8
9 def __init__(self):
10 # (image name, ordered modifiers tuple) -> pygame surface
11 self._cache = {}
12 self._modifiers = {}
13
14 def register_modifier(self, name, function):
15 """Register a post-load modifying function."""
16 if name in self._modifiers:
17 raise ValueError("Attempt to re-register and existing modifier function.")
18 self._modifiers[name] = function
19
20 def load_image(self, name, modifiers=None):
21 """Load an image from disk or return a cached image.
22
23 name: image name relative to data path.
24 modifers: ordered list of modifiers to apply.
25 """
26 # convert lists to tuples
27 if modifiers is not None:
28 modifiers = tuple(modifiers)
29
30 # convert empty tuples to None
31 if not modifiers:
32 modifiers = None
33
34 # look for modified image
35 key = (name, modifiers)
36 if key in self._cache:
37 return self._cache[key]
38
39 # look for unmodified image
40 base_key = (name, None)
41 if base_key in self._cache:
42 image = self._cache[base_key]
43 else:
44 image = pygame.image.load(data.filepath(name))
45 self._cache[base_key] = image
46
47 # handle unmodified case
48 if modifiers is None:
49 return image
50
51 for mod in modifiers:
52 image = self._modifiers[mod](image)
53
54 self._cache[key] = image
55 return image
56
57 # modifiers
58
59 from pygame.locals import BLEND_RGBA_MULT
60 NIGHT_COLOUR = (100.0, 100.0, 200.0, 255.0)
61
62 def convert_to_night(image):
63 """Convert a day tile to a night tile."""
64 night_image = image.copy()
65 night_image.fill(NIGHT_COLOUR, None, BLEND_RGBA_MULT)
66 return night_image
67
68 # globals
69
70 cache = ImageCache()
71 cache.register_modifier("night", convert_to_night)
72 load_image = cache.load_image