Update canvas image on button click event - python-3.x

Question

I'm trying to modify the displayed image on a canvas when a button is clicked on.
I have an object "Window" which will contain my window layers. this object contain a canvas named "draw_frame" and a button named "source_button". I add the command "self.load_static_source" to my button but when i click on my button nothing happen.
(Not exactely nothing because i tried to add default background in the init scope and when i click on my button after that the image on the canvas just diseappeared and the new selected image wasn't draw).
Here is my code:
from tkinter import *
from tkinter import filedialog
from PIL import Image, ImageTk
DARK_THEME = "grey"
LIGHT_THEME = "white"
THEME = LIGHT_THEME
class Window():
# object constructor
def __init__(self, root, theme):
# Sections #
self.toolbar_frame = LabelFrame(root, bg=theme, height="40")
self.toolbar_frame.pack(side=TOP, fill=X)
# Canvas #
self.draw_frame = Canvas(root)
self.draw_frame.pack(side=RIGHT, fill=BOTH, expand=True)
self.frame = self.draw_frame.create_image(0, 0, anchor=NW)
# Buttons #
self.source_button = Button(self.toolbar_frame, text="Source", bg=theme, command= lambda: self.load_static_source("./Sources/"))
self.source_button.pack(side=LEFT)
# Load image with tk compatibility
def load_image(self, path_):
print(path_) ### DEBUG ###
image = Image.open(path_)
return ImageTk.PhotoImage(image)
# Change canvas source with static one
def load_static_source(self, dir_):
path_ = filedialog.askopenfilename(initialdir = dir_, title = "Select file", filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
self.draw_frame.itemconfig(self.frame, image=self.load_image(path_))
root = Tk()
Window(root, THEME)
root.mainloop()
I found an other post talking about that and i can't find difference between what i did and the given solution and that's why i don't understand why that code isn't working.
Here are the exemple i found and the related post:
from Tkinter import *
#----------------------------------------------------------------------
class MainWindow():
#----------------
def __init__(self, main):
# canvas for image
self.canvas = Canvas(main, width=60, height=60)
self.canvas.grid(row=0, column=0)
# images
self.my_images = []
self.my_images.append(PhotoImage(file = "ball1.gif"))
self.my_images.append(PhotoImage(file = "ball2.gif"))
self.my_images.append(PhotoImage(file = "ball3.gif"))
self.my_image_number = 0
# set first image on canvas
self.image_on_canvas = self.canvas.create_image(0, 0, anchor = NW, image = self.my_images[self.my_image_number])
# button to change image
self.button = Button(main, text="Change", command=self.onButton)
self.button.grid(row=1, column=0)
#----------------
def onButton(self):
# next image
self.my_image_number += 1
# return to first image
if self.my_image_number == len(self.my_images):
self.my_image_number = 0
# change image
self.canvas.itemconfig(self.image_on_canvas, image = self.my_images[self.my_image_number])
#----------------------------------------------------------------------
root = Tk()
MainWindow(root)
root.mainloop()
Related post : stackoverflow topic

Answer 1

You need to keep a reference to the image. Here's a link to the effbot page describing it: https://effbot.org/tkinterbook/photoimage.htm
You must keep a reference to the image object in your Python program, either by storing it in a global variable, or by attaching it to another object.
The solution Xeyes wrote is right, and this page explains.

Answer 2

So i found the solution. A bit weird but it works. I have to save the image in a class attribute before i give it to the canvas itemconfig method.
It now looks like :
self.placeholder = self.load_image(path_)
self.draw_frame.itemconfig(self.frame, image=self.placeholder)
Instead of just :
self.draw_frame.itemconfig(self.frame, image=self.load_image(path_))