Why does Tkinter image not show up if created in a function?

问题

This code works:

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()

It shows me the image.

Now, this code compiles but it doesn\'t show me the image, and I don\'t know why, because it\'s the same code, in a class:

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()

回答1:

The variable photo is a local variable which gets garbage collected after the class is instantiated. Save a reference to the photo, for example:

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

If you do a Google search on "tkinter image doesn't display", the first result is this:

http://effbot.org/pyfaq/why-do-my-tkinter-images-not-appear.htm

回答2:

Just add global photo as the first line inside the function.

来源：https://stackoverflow.com/questions/16424091/why-does-tkinter-image-not-show-up-if-created-in-a-function