Now the balls don't move across the whole screen, but inside the space that they are given.

2 files changed, 39 insertions, 28 deletions

diff --git a/ball.py b/ball.py
index d4d1d46..6bbeea9 100644
--- a/ball.py
+++ b/ball.py
@@ -4,7 +4,6 @@ Created on Sat Sep 14 10:57:17 2013
 
 @author: laurent-bernabe
 """
-import pygame
 
 class Ball(object):
 
@@ -12,24 +11,26 @@ class Ball(object):
     An abstractation of a ball.
     """
 
-    def __init__(self, txt_font, txt_color, bg_color, operation, velocity):
+    def __init__(self, txt_font, txt_color, bg_color, operation,
+                 move_area, velocity = (0,0)):
         """
         Constructor
         txt_font : text font => olpcgames.pangofont
         txt_color : text color => Tuple of 3 integers in [0,255]
         bg_color : background color => Tuple of 3 integers in [0,255]
         operation : operation => An Operation value
-        velocity : current direction of move => A tuple of 2 floats (x,y)
+        move_area : space where ball is allowed to be => Tuple of 4 integers (
+        left side x, top side y, right side x, bottom side y)
+        velocity : current direction of move (so a (0,0) velocity for a fixed
+                   ball) => A tuple of 2 floats (x,y)
         """
-        info = pygame.display.Info()
-        self._SCREEN_WIDTH = info.current_w
-        self._SCREEN_HEIGHT = info.current_h        
         self._txt_font = txt_font
         self._txt_color = txt_color
         self._bg_color = bg_color
         self._operation = operation
         self._center = (0, 0)
         self._velocity = velocity
+        self._move_area = move_area
         txt_size = txt_font.size(operation.get_text())
         if txt_size[0] > txt_size[1]:
             max_txt_size = txt_size[0]
@@ -84,7 +85,14 @@ class Ball(object):
         Moves the ball to a particular place.
         new_center_position : the new center position => a tuple of 2 integers
         """
-        self._center = new_center_position
+        if (new_center_position[0] - self._diameter < self._move_area[0]
+           or new_center_position[0] + self._diameter > self._move_area[2]
+           or new_center_position[1] - self._diameter < self._move_area[1]
+           or new_center_position[1] + self._diameter > self._move_area[3]):
+            self._center = (self._move_area[0] + self._diameter,
+                            self._move_area[1] + self._diameter)
+        else:
+            self._center = new_center_position
 
     def move(self):
         """
@@ -97,13 +105,14 @@ class Ball(object):
         self._center = expected_new_center
         radius = self._diameter / 2 
         # Ball must not go across left or right wall.                
-        if (self._center[0] < radius 
-           or self._center[0] > self._SCREEN_WIDTH - radius):
+        if (self._center[0] < self._move_area[0] + radius 
+           or self._center[0] > self._move_area[2] - radius):
             self._velocity = (-self._velocity[0], self._velocity[1])
             self._center = (self._center[0] + self._velocity[0],
                             self._center[1] + self._velocity[1])
-        elif (self._center[1] < radius
-             or self._center[1] > self._SCREEN_HEIGHT - radius):
+        # Ball must not go across top or bottom wall.
+        elif (self._center[1] < self._move_area[1] + radius
+             or self._center[1] > self._move_area[3] - radius):
             self._velocity = (self._velocity[0], -self._velocity[1])
             self._center = (self._center[0] + self._velocity[0],
                             self._center[1] + self._velocity[1])
diff --git a/main.py b/main.py
index 2f75621..5ed65d8 100644
--- a/main.py
+++ b/main.py
@@ -23,6 +23,13 @@ def main():
     FPS = 40
     BACKGROUND = (255, 255, 255)
     TIME_BAR_HEIGHT = 20
+    BLACK = (0, 0, 0)
+    BLUE = (0, 0, 255)
+    YELLOW = (255, 255, 0)
+    RED = (255, 0, 0)
+    GREEN = (0, 255, 0)
+    DARK_GREEN = (0, 100, 0)
+    GRAY = (200, 200, 200)    
     if olpcgames.ACTIVITY:
         size = olpcgames.ACTIVITY.game_size
         screen = pygame.display.set_mode(size)
@@ -32,31 +39,26 @@ def main():
         pygame.display.set_caption("Hit the balls")
     clock = pygame.time.Clock()
     font = PangoFont(family='Helvetica', size=16, bold=True)
-    BLACK = (0, 0, 0)
-    BLUE = (0, 0, 255)
-    YELLOW = (255, 255, 0)
-    RED = (255, 0, 0)
-    GREEN = (0, 255, 0)
-    DARK_GREEN = (0, 100, 0)
-    GRAY = (200, 200, 200)
+    
+    time_bar = TimeBar(size[0], TIME_BAR_HEIGHT, DARK_GREEN, GRAY)
+    time_bar.start(1000, 1)
+    
+    balls_area = (0, TIME_BAR_HEIGHT, size[0], size[1])
     
     the_balls = [Ball(font, BLACK, BLUE, 
-                      Operation(1000, 3000, OPER_MUL), (2, 1.2)),
+                      Operation(1000, 3000, OPER_MUL), balls_area, (2, 1.2)),
                  Ball(font, BLACK, YELLOW, 
-                      Operation(120, 45, OPER_SUB), (1.6,-0.4)),
+                      Operation(120, 45, OPER_SUB), balls_area, (1.6,-0.4)),
                  Ball(font, BLACK, RED, 
-                      Operation(9, 3, OPER_DIV), (-0.8, 1.6)),
+                      Operation(9, 3, OPER_DIV), balls_area, (-0.8, 1.6)),
                  Ball(font, BLACK, GREEN,
-                      Operation(120, 240, OPER_ADD), (1.7, -1.2))]
+                      Operation(120, 240, OPER_ADD), balls_area, (1.7, -1.2))]
                 
 
-    the_balls[0].move_to((140, 170))
-    the_balls[1].move_to((400, 300))
+    the_balls[0].move_to((430, 200))
+    the_balls[1].move_to((400, 360))
     the_balls[2].move_to((200, 80))
-    the_balls[3].move_to((330, 70))
-    
-    time_bar = TimeBar(size[0], TIME_BAR_HEIGHT, DARK_GREEN, GRAY)
-    time_bar.start(1000, 1)
+    the_balls[3].move_to((330, 100))
     
     while True:
         screen.fill(BACKGROUND)