+ def _render(self, layer):
+ # We cache the rendered surface to avoid doing a large number
+ # of blits each frame, as that introduces a large performance
+ # overhead.
+ surface = Surface((len(self._tiles[0]) * TILE_SIZE,
+ len(self._tiles) * TILE_SIZE))
+ layer_key = '%s image' % layer
+ for y, row in enumerate(self._tiles):
+ for x, tile in enumerate(row):
+ pos = (x * TILE_SIZE, y * TILE_SIZE)
+ if layer_key not in tile:
+ # Skip broken tiles for now
+ continue
+ surface.blit(tile[layer_key], pos)
+ return surface.convert_alpha()
+
+ def draw(self, screen, viewport):