Tkinter create shrinking circle on each mouse click, how to make it work with multiple clicks? - python-3.x

Question

I am creating a simple program which draws a shrinking circle of random color on every clicked location by each mouse click. Each click creates a circle of diameter 50 which starts shrinking till 0 immediately. Each click is supposed to create new shrinking circle.
However, my program stops shrinking of first circle after I click and create another circle. It completely shrinks only the last created circle. All others remain still.
I believe the problem lies in function itself. It calls the same function which is not finished. How to make it run multiple times (on each click separately)? Or do I have it wrong with local and global variables?
Here is my code so far:
import tkinter
import random
c = tkinter.Canvas(width = 400, height = 300)
c.pack()
def klik(event):
global x, y, farba, circ, r
r = 50 #circle diameter
x, y = event.x, event.y #clicked position
color = '#{:06x}'.format(random.randrange(256 ** 3)) #random color picker
circ = c.create_oval(x - r, y - r, x + r, y + r, fill=color) #print circle
print(x, y, farba) #check clicked coordinates, not important
if r < 50: #reset size after each circle
r = 50
shrink()
def shrink():
global circ, x, y, r
print(r) #check if countdown runs correctly
if r > 0:
r -= 1 #diameter shrinking
c.coords(circ, x-r, y-r, x+r, y+r) #changing circle size
c.after(100, shrink) #timer, size 1pt smaller until size is 0
c.bind('<Button-1>', klik)
tkinter.mainloop()

Answer 1

If you move everything into a class then each circle will be its own instance and will not interfere with each other.
Take a look at the below modified version of your code. It is probably not perfect but should be a good foundation for you to work with.
import tkinter
import random
c = tkinter.Canvas(width = 400, height = 300)
c.pack()
class create_circles():
def __init__(self, event):
self.r = 50
self.x, self.y = event.x, event.y
self.color = '#{:06x}'.format(random.randrange(256 ** 3))
self.circ = c.create_oval(self.x - self.r, self.y - self.r, self.x + self.r, self.y + self.r, fill=self.color)
self.shrink()
def shrink(self):
if self.r > 0:
self.r -= 1
c.coords(self.circ, self.x-self.r, self.y-self.r, self.x+self.r, self.y+self.r)
c.after(100, self.shrink)
c.bind('<Button-1>', create_circles)
tkinter.mainloop()
There is another way you can do this outside of a class.
You can use a nested function and avoid global. Your issues in your question is actually being caused because everything relies on global variables.
Try this below code for a non-class option.
import tkinter
import random
c = tkinter.Canvas(width = 400, height = 300)
c.pack()
def klik(event):
r = 50
x, y = event.x, event.y
color = '#{:06x}'.format(random.randrange(256 ** 3))
circ = c.create_oval(x - r, y - r, x + r, y + r, fill=color)
def shrink(r, x, y, color, circ):
if r > 0:
r -= 1
c.coords(circ, x-r, y-r, x+r, y+r)
c.after(100, shrink, r, x, y, color, circ)
shrink(r, x, y, color, circ)
c.bind('<Button-1>', klik)
tkinter.mainloop()

Answer 2

As noted, you do not need classes to solve this nor nested functions. The key, as #LioraHaydont was hinting at, is you need to use local, rather than global variables:
import tkinter as tk
from random import randrange
def klik(event):
r = 50 # circle radius
x, y = event.x, event.y # clicked position
color = '#{:06x}'.format(randrange(256 ** 3)) # random color picker
c = canvas.create_oval(x - r, y - r, x + r, y + r, fill=color) # print circle
canvas.after(100, shrink, c, x, y, r)
def shrink(c, x, y, r):
if r > 0:
r -= 1 # radius shrinking
canvas.coords(c, x - r, y - r, x + r, y + r) # changing circle size
canvas.after(100, shrink, c, x, y, r) # timer, size 1pt smaller until size is 0
canvas = tk.Canvas(width=400, height=300)
canvas.pack()
canvas.bind('<Button-1>', klik)
tk.mainloop()