optimize tiles drawing

survival/textureatlas.py

@@ -4,15 +4,19 @@ import pygame
 class TextureAtlas(object):
     def __init__(self, filename):
         self.atlas = pygame.image.load(filename).convert()
+        self.images = {}
 
     def image_at(self, origin, target, color_key=None):
+        if origin in self.images:
+            return self.images[origin]
         rect = pygame.Rect(origin, target)
         image = pygame.Surface(rect.size).convert()
         image.blit(self.atlas, (0, 0), rect)
         if color_key is not None:
-            if color_key is -1:
+            if color_key == -1:
                 color_key = image.get_at((0, 0))
             image.set_colorkey(color_key, pygame.RLEACCEL)
+        self.images[origin] = image
         return image
 
     def images_at(self, rects, color_key=None):

survival/tile.py

@@ -1,3 +1,4 @@
 class Tile:
     def __init__(self):
         self.origin = (0, 0)
+        self.image = None

survival/tile_layer.py

@@ -10,8 +10,15 @@ class TileLayer:
         self.height = height
         self.tiles = [[Tile() for x in range(self.width)] for y in range(self.height)]
         self.atlas = TextureAtlas(os.path.join('..', 'assets', 'atlas.png'))
+        self.loadTiles()
+
+    def loadTiles(self):
+        for y in range(self.height):
+            for x in range(self.width):
+                self.tiles[y][x].image = self.atlas.image_at(self.tiles[y][x].origin, (32, 32))
 
     def draw(self, window):
         for y in range(self.height):
             for x in range(self.width):
-                window.blit(self.atlas.image_at(self.tiles[y][x].origin, (32, 32)), (x * 32, y * 32))
+                if self.tiles[y][x] is not None:
+                    window.blit(self.tiles[y][x].image, (x * 32, y * 32))