""" Scene utilities. """
+import functools
+
+
+def apply_events(f):
+ """ Decorator that applies events to an engine. """
+ @functools.wraps(f)
+ def wrap(self, *args, **kw):
+ events = f(self, *args, **kw)
+ self._apply_events(events)
+ return wrap
+
+
+class Engine:
+ """ A holder for game state & scene management.
+ """
+
+ def __init__(self, app, scene, world):
+ self._app = app
+ self._scene = scene
+ self._world = world
+ self._viewport = (0, 0)
+
+ def _apply_events(self, events):
+ if not events:
+ return
+ for ev in events:
+ ev.apply(self)
+
+ def change_scene(self, scene):
+ self._apply_events(self._scene.exit(self._world))
+ self._scene = scene
+ self._apply_events(self._scene.enter(self._world))
+
+ def change_world(self, *args, **kw):
+ self._world.apply_event(*args, **kw)
+
+ def quit_game(self):
+ from pgzero.game import exit
+ exit()
+
+ def move_screen(self, offset):
+ self._viewport = (self._viewport[0] + offset[0],
+ self._viewport[1] + offset[1])
+
+ @apply_events
+ def update(self, dt):
+ return self._scene.update(self._world, dt)
+
+ def draw(self):
+ self._scene.draw(self._app.screen, self._viewport)
+
+ @apply_events
+ def on_mouse_down(self, pos, button):
+ return self._scene.on_mouse_down(pos, button)
+
+ @apply_events
+ def on_mouse_up(self, pos, button):
+ return self._scene.on_mouse_up(pos, button)
+
+ @apply_events
+ def on_key_down(self, key, mod, unicode):
+ return self._scene.on_key_down(key, mod, unicode)
+
+ @apply_events
+ def on_key_up(self, key, mod):
+ return self._scene.on_key_up(key, mod)
+
+ @apply_events
+ def on_music_end(self):
+ return self._scene.on_music_end()
+
+
+class Event:
+ """ Base class for events. """
+
+ ENGINE_METHOD = "unknown_event"
+
+ def __init__(self, *args, **kw):
+ self._args = args
+ self._kw = kw
+
+ def apply(self, engine):
+ getattr(engine, self.ENGINE_METHOD)(*self._args, **self._kw)
+
+
+class ChangeSceneEvent(Event):
+ """ Change to a new scene. """
+
+ ENGINE_METHOD = "change_scene"
+
+
+class WorldEvent(Event):
+ """ Be a hero. Change the world. """
+
+ ENGINE_METHOD = "change_world"
+
+
+class QuitEvent(Event):
+ """ Quit the game. """
+
+ ENGINE_METHOD = "quit_game"
+
+
+class MoveViewportEvent(Event):
+ """ Change to a new scene. """
+
+ ENGINE_METHOD = "move_screen"
+
+
+class Actors:
+ """ A list of actors. """
+
+ def __init__(self):
+ self._actors = []
+
+ def add(self, actor):
+ self._actors.append(actor)
+ return actor
+
+ def remove(self, actor):
+ self._actors.remove(actor)
+ return actor
+
+ def draw(self, screen):
+ for actor in self._actors:
+ actor.draw() # TODO: allow an option screen to be passed in
+
class Scene:
""" Base class for scenes. """
- def update(self, dt):
+ def __init__(self):
+ self.actors = Actors()
+
+ def enter(self, world):
pass
- def draw(self, screen):
+ def exit(self, world):
+ pass
+
+ def update(self, world, dt):
+ pass
+
+ def draw(self, screen, viewport):
+ screen.clear()
+ self.actors.draw(screen)
+
+ def on_mouse_down(self, pos, button):
+ pass
+
+ def on_mouse_up(self, pos, button):
+ pass
+
+ def on_key_down(self, key, mod, unicode):
+ pass
+
+ def on_key_up(self, key, mod):
+ pass
+
+ def on_music_end(self):
pass