Move viewport management down into the engine and add suitable events. Cache initial...

[koperkapel.git] / koperkapel / scenes / base.py

diff --git a/koperkapel/scenes/base.py b/koperkapel/scenes/base.py
index 58f3874f204b87a874751d593f4360a785791a70..c6b8752d41de58893a8ac3174ace3f2b37b5c284 100644 (file)
--- a/koperkapel/scenes/base.py
+++ b/koperkapel/scenes/base.py
@@ -18,6 +18,7 @@ class Engine:
     def __init__(self, app, scene):
         self._app = app
         self._scene = scene
+        self._viewport = (0, 0)
 
     def _apply_events(self, events):
         if not events:
@@ -34,12 +35,16 @@ class Engine:
         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(dt)
 
     def draw(self):
-        self._scene.draw(self._app.screen)
+        self._scene.draw(self._app.screen, self._viewport)
 
     @apply_events
     def on_mouse_down(self, pos, button):
@@ -87,6 +92,12 @@ class QuitEvent(Event):
     ENGINE_METHOD = "quit_game"
 
 
+class MoveViewportEvent(Event):
+    """ Change to a new scene. """
+
+    ENGINE_METHOD = "move_screen"
+
+
 class Actors:
     """ A list of actors. """
 
@@ -121,7 +132,7 @@ class Scene:
     def update(self, dt):
         pass
 
-    def draw(self, screen):
+    def draw(self, screen, viewport):
         screen.clear()
         self.actors.draw(screen)