Why Doesn't My Tkinter Image Appear Inside a Class?

Tkinter Image Unavailable in Class

In Tkinter, creating images within a function can lead to unexpected behavior. While the following code outside a class successfully displays an image:

import tkinter

root = tkinter.Tk()
canvas = tkinter.Canvas(root)
canvas.grid(row=0, column=0)
photo = tkinter.PhotoImage(file='./test.gif')
canvas.create_image(0, 0, image=photo)
root.mainloop()

The same code placed within a class does not render the image:

import tkinter

class Test:
    def __init__(self, master):
        canvas = tkinter.Canvas(master)
        canvas.grid(row=0, column=0)
        photo = tkinter.PhotoImage(file='./test.gif')
        canvas.create_image(0, 0, image=photo)

root = tkinter.Tk()
test = Test(root)
root.mainloop()

Solution: Scope of Image Reference

The issue arises because the photo variable is a local variable within the class constructor. Once the constructor finishes, the variable is discarded by the garbage collector. To ensure that the image remains visible, the reference to the photo variable must be stored within the class. This can be achieved by modifying the code to:

class Test:
    def __init__(self, master):
        self.canvas = tkinter.Canvas(master)
        self.canvas.grid(row=0, column=0)
        self.photo = tkinter.PhotoImage(file='./test.gif')
        self.canvas.create_image(0, 0, image=self.photo)

root = tkinter.Tk()
test = Test(root)
root.mainloop()

By assigning the photo variable to self.photo, a reference to the image is maintained even after the constructor has completed. This allows the image to be displayed within the class.

Searching for Tkinter Image Issues

If you encounter similar issues with Tkinter images not appearing, remember that searching for relevant documentation or forum threads can provide valuable insights into the cause and solution. By understanding the scope of variables and how to maintain references, you can effectively display images within Tkinter applications.

The above is the detailed content of Why Doesn't My Tkinter Image Appear Inside a Class?. For more information, please follow other related articles on the PHP Chinese website!