在 tk Button 中使用图像时，Button 消失

Question

Here is my code, you can ignore most of them but only see the last part which have #

import tkinter as tk
from PIL import ImageTk, Image

def bresize_and_load(path):
    global bwidth, bheight
    im = Image.open(path)
    bwidth,bheight = im.size    
    resized = bresizemode(im, bwidth, bheight)    
    width,height = resized.size    
    return ImageTk.PhotoImage(resized)

def bresizemode(im, width, height):
    if height / width >= ratio:
        return im.resize((int(round((width / height) * usable_height)), usable_height), 
                  Image.ANTIALIAS)
       
    if height / width < ratio:
        return im.resize((usable_width, (int(round((height / width) * usable_width)))), 
                  Image.ANTIALIAS)

root = tk.Tk()
root.state("zoomed")
root.resizable(width=False, height=False)

frame = tk.Frame(root)

frame.grid(row = 0, column = 0, sticky = 'nsew')

tk.Grid.rowconfigure(root, 0, weight=1)
tk.Grid.columnconfigure(root, 0, weight=1)

row = 4
column = 5
for ro in range(row):
    tk.Grid.rowconfigure(frame, ro, weight=1)
for co in range(column):
    tk.Grid.columnconfigure(frame, co, weight=1)

root.update()
f_width  = frame.winfo_width()
f_height = frame.winfo_height()

booklistbutton = []
for i in range(row):
    for e in range(column):
        bbutton = tk.Button(frame, height = int(f_height / row), 
                            width = int(f_width / column))
        bbutton.grid(row = i, column = e)
        booklistbutton.append(bbutton)

root.update()
usable_width = booklistbutton[0].winfo_width()
usable_height = booklistbutton[0].winfo_height()
ratio = usable_height / usable_width

#here is image path
path = 'sample.jpg'
imm = []

#if it is range(20)(just = row * column) or less than column(here is 5), it work fine
for i in range(20):    
    imm.append(bresize_and_load(path))
    booklistbutton[i].config(image = imm[i])

root.mainloop()

My question is, if you load image in button, but the number of imaged buttons is not less than column or equal row * column, the imaged buttons will disappear.

When range equal row * column(20):

When range is 6:

This is weird for me, does anyone have any idea?

Also, if you do not set button's width and height, they won't disappear. But buttons will little bigger than images.

Answer 1

(Posted solution on behalf of the OP) .

I find the problem by myself, the problem is when I set the Buttons' size, it is chr size, but when I load a image, it change to pixel size, and at the same size number, chr size is bigger and bigger than pixel size, so the imaged button become too small to show.