Blank images when attempting to load image into tkinter window

Question

So what's happening is that I have a PNG file saved in my directory. I am trying to create a program that loads this picture onto a window 3 times. I am using tkinter for the UI and its PhotoImage class to do this. To load a picture I normally create a class and then load put a button in it with the 'image parameter'. However, when I try to run this program, it only loads the 3rd picture. The 1st and 2nd one just appear as blank boxes. Can somebody help me? The code is below:

from tkinter import *

def add():
    imageClass = PhotoImage(file="updated.png")
    button = Button(root, compound=TOP, image=imageClass, pady=20, bd=0, highlightthickness=0)
    button.pack()

root = Tk()

root.config(bg="white")

for i in range(3):
    root.update()
    imageClass = PhotoImage(file="updated.png")
    button = Button(root, compound=TOP, image=imageClass, pady=20, bd=0, highlightthickness=0)
    button.pack()
root.mainloop()

Sorry, please ignore the 'add' function. I was using it for something else but i forgot to remove it — Harman Punchi, Jul 22 '20 at 13:02
Why don't you just move the line `imageClass = PhotoImage(...)` before the for loop if all the buttons use the same picture? — acw1668, Jul 23 '20 at 03:59

score 0 · Accepted Answer · answered Jul 22 '20 at 13:53

What's happening is your images are being stored on every iteration of the for loop as imageClass = PhotoImage(file="updated.png")

imageClass gets its value overriden for every i, and when the loop finally exits only one reference in imageClass remains, hence why the 3rd image appers and others do not.

Thus you need to store every PhotoImage "reference" somewhere, for example in a global dictionary

root = Tk()

# Modification 1
myImageClasses = dict()

root.config(bg="white")

for i in range(3):
    root.update()
    # Modification 2
    myImageClasses[i] = PhotoImage(file="updated.png")
    button = Button(root, compound=TOP, image=myImageClasses[i], pady=20, bd=0, highlightthickness=0)
    button.pack()

root.mainloop()

Oh, I totally understand now! Thanks so much everyone who helped me — Harman Punchi, Jul 27 '20 at 11:00

Blank images when attempting to load image into tkinter window

1 Answers1