Enlarge Shrink Circle

from tkinter import * # Import all definitons from tkinter

class EnlargeShrinkCircle:
    def __init__(self):
        self.radius = 50

        window = Tk() # Create a window
        window.title("Control Circle Demo")  # Set a title
        self.canvas = Canvas(window, bg = "white", width = 200, height = 200)
        self.canvas.pack()
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius, 100 + self.radius, 100 + self.radius,
            tags = "oval")

        # Bind canvas with mouse events
        self.canvas.bind("<Button-1>", self.increaseCircle)
        self.canvas.bind("<Button-3>", self.decreaseCircle)

        window.mainloop()  # Create an event loop

    def increaseCircle(self, event):
        self.canvas.delete("oval")
        if self.radius  < 100:
            self.radius += 2
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius, 100 + self.radius, 100 + self.radius,
            tags="oval")

    def decreaseCircle(self, event):
        self.canvas.delete("oval")
        if self.radius > 2:
            self.radius -= 2
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius, 100 + self.radius, 100 + self.radius,
            tags="oval")


EnlargeShrinkCircle() # Create GUI