Why Aren't My Tkinter Images Displaying Inside Classes?

Why Tkinter Image Fails to Display in Classes: A Curious Case

In Tkinter, a popular GUI library for Python, it's often encountered that images fail to appear when created within functions or class methods. Let's delve into the reason behind this peculiar behavior.

When using Tkinter outside of a class, it's straightforward to create and display images. As demonstrated in the first code snippet, simply declare the image using tkinter.PhotoImage and assign it to the canvas. However, when the code is wrapped within a class (as shown in the second snippet), the image stops rendering.

The key to the problem lies in understanding Python's variable lifetime. Local variables, such as the photo variable in the provided example, exist only within the scope of the function or method they are defined in. In the case of the class, the photo variable is destroyed after the class instance is created, making Tkinter unable to access it anymore.

To remedy this situation, it's necessary to store a reference to the image outside the scope of the function or method. This can be achieved by assigning the photo variable to the class instance itself. As demonstrated in the solution provided:

self.photo = tkinter.PhotoImage(...)

By doing so, photo becomes an instance variable and its lifetime is extended for the duration of the class instance's existence. This allows Tkinter to access the image and display it as expected.

If facing similar issues with images failing to appear in Tkinter, remember to check the scope of your image variables and ensure they persist beyond the function or method in which they are created.

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