tkinter example EnlargeShrinkCircle (snippet)

Python tkinter (gui) example 'EnlargeShrinkCircle'

EnlargeShrinkCircle

Python tkinter example: EnlargeShrinkCircle

from tkinter import * # Import 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

Useful links

• Learn Tkinter: https://pythonbasics.org/tkinter/
• Wikipedia tkinter: https://en.wikipedia.org/wiki/Tkinter