# Examples of mouse input

import simplegui

import math

# intialize globals

width = 450

height = 300

ball_list = []

ball_radius = 15

ball_color = "Red"

# helper function

def distance(p, q):

return math.sqrt((p[0] - q[0]) ** 2 + (p[1] - q[1]) ** 2)

# define event handler for mouse click, draw

def click(pos):

remove = []

for ball in ball_list:

if distance(ball, pos) < ball_radius:

remove.append(ball)

if remove == []:

ball_list.append(pos)

else:

for ball in remove:

ball_list.pop(ball_list.index(ball))

def draw(canvas):

for ball in ball_list:

canvas.draw_circle([ball[0], ball[1]], ball_radius, 1, "Black", ball_color)

# create frame

frame = simplegui.create_frame("Mouse selection", width, height)

frame.set_canvas_background("White")

# register event handler

frame.set_mouseclick_handler(click)

frame.set_draw_handler(draw)

# start frame

frame.start()