Created the main game loop and started writing the game's states.

game.py

@@ -0,0 +1,84 @@
+# Miguel Angel Astor Romero. Created on 7-1-2012. #
+###################################################
+import pygame
+
+try:
+   import android
+except ImportError:
+   android = None
+
+from state import VALID_STATES
+from intro import IntroState
+from menu import MenuState
+from ingame import InGameState
+from score import ScoreState
+from notvalidstate import NotValidState
+
+# Debug constant. Comment to turn off debugging messages.
+DEBUG = True
+
+# The Game class implements the state machine of the game and
+# runs the main game loop.
+class Game:
+    def __init__(self, screen):
+        """ Sets the rendering canvas and the intial state. """
+        self.canvas = screen
+        self.current_state = VALID_STATES['INTRO']
+        self.done = False
+        self.clock = pygame.time.Clock()
+        
+        # Initialize the different game states.
+        intro = IntroState()
+        menu = MenuState()
+        in_game = InGameState()
+        score = ScoreState()
+        not_valid = NotValidState()
+        
+        # Create a states list.
+        self.state_vector = [intro, menu, in_game, score, not_valid]
+
+    def get_state(self):
+       """ Returns the current state of the game. """
+       if self.current_state == VALID_STATES['INTRO']:
+          return "INTRO"
+       elif self.current_state == VALID_STATES['MENU']:
+          return "MENU"
+       elif self.current_state == VALID_STATES['IN_GAME']:
+          return "IN_GAME"
+       elif self.current_state == VALID_STATES['SCORE']:
+          return "SCORE"
+       elif self.current_state == VALID_STATES['QUIT']:
+          return "QUIT"
+       else:
+          return "NOT_VALID"
+
+    def game_loop(self):
+        """ The main game loop. """
+        while not self.done:
+           # Get user input first.
+           self.state_vector[self.current_state].input()
+           # Then update the game state.
+           transition = self.state_vector[self.current_state].update()
+           # Check if a state transition is required.
+           if transition != VALID_STATES['STAY']:
+              if transition == VALID_STATES['INTRO']:
+                 self.current_state = VALID_STATES['INTRO']
+              elif transition == VALID_STATES['MENU']:
+                 self.current_state = VALID_STATES['MENU']
+              elif transition == VALID_STATES['IN_GAME']:
+                 self.current_state = VALID_STATES['IN_GAME']
+              elif transition == VALID_STATES['SCORE']:
+                 self.current_state = VALID_STATES['SCORE']
+              elif transition == VALID_STATES['QUIT']:
+                 self.done = True
+                 self.current_state = VALID_STATES['QUIT']
+              else:
+                 self.current_state = VALID_STATES['NOT_VALID']
+              if DEBUG:
+                 print self.get_state()
+           # If the game is not over, render the current state.
+           if not self.done:
+              self.state_vector[self.current_state].render(self.canvas)
+              pygame.display.update()
+              self.clock.tick(60)
+