Recently I was puzzled by a tkinter problem. The codes below (from a book) can
display the picture correctly.
gifdir = "../gifs/"
from tkinter import *
win = Tk()
photo = PhotoImage(file=gifdir + "ora-pp.gif")
Button(win, image=photo).pack()
win.mainloop()
And the codes below (from another book) will also work.
class DrumMachine:
....
....
def create_play_bar(self):
....
....
photo = PhotoImage(file='images/signature.gif')
label = Label(playbar_frame, image=photo)
label.image = photo
label.grid(row=start_row, column=50, padx=1, sticky='w')
....
....
In the second example, I noticed that the "photo" was referenced two times and
I think it might be a redundancy so I remove the line "label.image = photo".
But it fails then.
How can it be? one works and the other not.
I search for answers on the web and here are some links talking about it:
http://stackoverflow.com/questions/20812579/why-it-shows-blank-instead-of-picture-in-my-tkinter-program
http://effbot.org/tkinterbook/photoimage.htm
They all said that you have to keep a reference to the "photo" or else it will
be garbage collected. Now, as I had learn Python so far, I know that a keyword
argument passed in an object instantiation will bind this object to its
attribute name, i.e. create a reference to this object. (and it should or the
whole language will be in disaster)
Can anyone help me out?
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