Fixed lag and missed input issues.

Author: jamesbgd

Snake.py

@@ -22,19 +22,30 @@ def __init__(self, startX, startY):
     def getSize(self):
         return self.snakeSize
 
-    def changeDir(self, keyPress):
-        if keyPress[K_UP] and self.yVel != MAX_VEL:
+    def changeDir(self, keyEvent):
+        """ keEvent --> Bool
+        changeDir takes a pygame KEYDOWN event and changes the direction of
+        the Snake if the event was an arrow key.
+        The boolean return tells whether the direction was changed or not.
+        """
+        didChangeDir = False
+        if keyEvent.key == K_UP and self.yVel != MAX_VEL:
             self.xVel = 0
             self.yVel = -MAX_VEL
-        elif keyPress[K_DOWN] and self.yVel != -MAX_VEL:
+            didChangeDir = True
+        elif keyEvent.key == K_DOWN and self.yVel != -MAX_VEL:
             self.xVel = 0
             self.yVel = MAX_VEL
-        elif keyPress[K_LEFT] and self.xVel != MAX_VEL:
+            didChangeDir = True
+        elif keyEvent.key == K_LEFT and self.xVel != MAX_VEL:
             self.xVel = -MAX_VEL
             self.yVel = 0
-        elif keyPress[K_RIGHT] and self.xVel != -MAX_VEL:
+            didChangeDir = True
+        elif keyEvent.key == K_RIGHT and self.xVel != -MAX_VEL:
             self.xVel = MAX_VEL
             self.yVel = 0
+            didChangeDir = True
+        return didChangeDir
 
     def moveSnake(self):
         self.lastPos =  self.body[-1]

SnakeGame.py

@@ -57,9 +57,9 @@ def drawScore(self, surface):
         surface.blit(scoreSurface, (self.scorePosX, 0))
 
     def drawSplashScreen(self, surface, text, color):
-        ''' Surface, String --> void
+        """ Surface, String --> void
         Draws text centered at the center of the given Surface.
-        '''
+        """
         splashFont = pygame.font.Font(None, 100)
         splashSurface = splashFont.render(text, True, color)
         textXPos = (SCREEN_SIZE[0] // 2) - (splashFont.size(text)[0] // 2)
@@ -84,22 +84,24 @@ def play(self):
             if event.type == KEYDOWN:
                 break
 
-        while True:#self.playing: # main loop for running the game
+        while True:# main loop for running the game
+            pygame.event.pump()
             SCREEN.blit(BG, (0, 0)) # Makes clean background
             self.apple.drawApple(SCREEN, self.snake.getSize())
             self.snake.drawSnake(SCREEN)
             self.drawScore(SCREEN)
             pygame.display.flip()
 
-            # Move the snake
-            self.snake.moveSnake()
-
             # Handle Key events
+            didChangeDir = False
             for event in pygame.event.get():
                 self.handleQuit(event)
-            pressedKeys = pygame.key.get_pressed()
-            self.snake.changeDir(pressedKeys)
+                if event.type == KEYDOWN and not didChangeDir:
+                    didChangeDir = self.snake.changeDir(event)
 
+            # Move the snake
+            self.snake.moveSnake()
+
             # Handle Collisions
             if self.isSnakeCollision():
                 self.snake.drawSnake(SCREEN) # update the snake's position to when it crashed
@@ -121,6 +123,8 @@ def play(self):
 
 def main():
     pygame.init()
+    pygame.event.set_allowed(None) # No event types are allowed on queue
+    pygame.event.set_allowed([QUIT, KEYDOWN])
     while True:
         game = SnakeGame()
         game.play()