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# 10.35 (Tkinter: bouncing balls) Revise Listing 10.13 to add two buttons—Faster and
# Slower, as shown in Figure 10.16b—to speed up or slow down the ball
# movements.
from tkinter import * # Import tkinter
from random import randint
# Return a random color string in the form #RRGGBB
def getRandomColor():
color = "#"
for j in range(6):
color += toHexChar(randint(0, 15)) # Add a random digit
return color
# Convert an integer to a single hex digit in a character
def toHexChar(hexValue):
if 0 <= hexValue <= 9:
return chr(hexValue + ord('0'))
else: # 10 <= hexValue <= 15
return chr(hexValue - 10 + ord('A'))
# Define a Ball class
class Ball:
def __init__(self):
self.x = 0 # Starting center position
self.y = 0
self.dx = 2 # Move right by default
self.dy = 2 # Move down by default
self.radius = 3 # The radius is fixed
self.color = getRandomColor() # Get random color
class BounceBalls:
def __init__(self):
self.ballList = [] # Create a list for balls
self.speed = 1
window = Tk() # Create a window
window.title("Bouncing Balls") # Set a title
self.width = 350 # Width of the self.canvas
self.height = 150 # Width of the self.canvas
self.canvas = Canvas(window, bg="white",
width=self.width, height=self.height)
self.canvas.pack()
frame = Frame(window)
frame.pack()
btStop = Button(frame, text="Stop", command=self.stop)
btStop.pack(side=LEFT)
btResume = Button(frame, text="Resume",
command=self.resume)
btResume.pack(side=LEFT)
btAdd = Button(frame, text="+", command=self.add)
btAdd.pack(side=LEFT)
btRemove = Button(frame, text="-", command=self.remove)
btRemove.pack(side=LEFT)
btFaster = Button(frame, text="Faster", command=self.fast)
btFaster.pack(side=LEFT)
btSlower = Button(frame, text="Slower", command=self.slow)
btSlower.pack(side=LEFT)
self.sleepTime = 100 # Set a sleep time
self.isStopped = False
self.animate()
window.mainloop() # Create an event loop
def stop(self): # Stop animation
self.isStopped = True
def resume(self): # Resume animation
self.isStopped = False
self.animate()
def add(self): # Add a new ball
self.ballList.append(Ball())
def remove(self): # Remove the last ball
self.ballList.pop()
def animate(self): # Move the message
while not self.isStopped:
self.canvas.after(self.sleepTime) # Sleep
self.canvas.update() # Update self.canvas
self.canvas.delete("ball")
for ball in self.ballList:
self.redisplayBall(ball)
def redisplayBall(self, ball):
if ball.x > self.width or ball.x < 0:
ball.dx = -ball.dx
if ball.y > self.height or ball.y < 0:
ball.dy = -ball.dy
ball.x += ball.dx * self.speed
ball.y += ball.dy * self.speed
self.canvas.create_oval(ball.x - ball.radius,
ball.y - ball.radius, ball.x + ball.radius,
ball.y + ball.radius, fill=ball.color, tags="ball")
def fast(self):
self.speed += 1
def slow(self):
if self.speed > 1:
self.speed -= 1
BounceBalls() # Create GUI
