CODEWITHSUNDEEP
pythonpython-3.xtkinter
Jake
Jake

Reputation: 892

Make function that only runs only once after it has been clicked the first time using Tkinter?

In tkinter, python, I'm trying to create a program which involves creating a shape onto a canvas and with a button click, and cause no more shapes to be created. Here's my code:

from tkinter import *

root = Tk()
canvas = Canvas(root)  # Creating Canvas
canvas.pack()

def create(event):
    x1, y1 = (event.x - 5), (event.y - 5)
    x2, y2 = (event.x + 5), (event.y + 5)         # Creates Rectangle Where Button Clicked
    canvas.create_rectangle(x1,y1,x2,y2,fill='red')

root.bind_all("<Button-1>", create)  # Binds Mouse Click Button


citybg = PhotoImage(file= r"example.png") 
citybgimage = canvas.create_image(50, 50, image=citybg) # Background for Canvas

My question is how to make the rectangle only create able once and once only, and the create function can no longer be executed. Hope this was explained well, and I hope it can be answered well.

Upvotes: 0

Views: 1496

Answers (3)

Mia
Mia

Reputation: 2676

I think you can unbind the function after finish running the function. Like this:

def create(event):
    x1, y1 = (event.x - 5), (event.y - 5)
    x2, y2 = (event.x + 5), (event.y + 5)    # Creates Rectangle Where Button Clicked
    canvas.create_rectangle(x1,y1,x2,y2,fill='red')
    root.unbind_all('<Button-1>') #You can later bind <Button-1> to other functions as well

Upvotes: 0

Dozon Higgs
Dozon Higgs

Reputation: 565

Well, a simple solution (but not that pretty) will be to add a Boolean flag that will be set as True when the function run for the first time. Then use if statement and return and not do anything in create if True.

something like this (createRan - is that Boolean flag):

root = Tk()
canvas = Canvas(root)  # Creating Canvas
canvas.pack()
createRan = False


def create(event):
    if(createRan):
        return
    else:
        createRan=True
        x1, y1 = (event.x - 5), (event.y - 5)
        x2, y2 = (event.x + 5), (event.y + 5)         # Creates  Rectangle Where Button Clicked
        canvas.create_rectangle(x1,y1,x2,y2,fill='red')

Upvotes: 2

Guillaume A.
Guillaume A.

Reputation: 161

Use a boolean to check whether the rectangle has already been created or not, like that :

rectangleCreated = False

def create(event):
    if rectangleCreated:
        return
    x1, y1 = (event.x - 5), (event.y - 5)
    x2, y2 = (event.x + 5), (event.y + 5)
    canvas.create_rectangle(x1,y1,x2,y2,fill='red')
    rectangleCreated = True

Upvotes: 3

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