How to Clear or Overwrite a Tkinter Canvas

How to clear Tkinter Canvas?

Every canvas item is an object that Tkinter keeps track of. If you are clearing the screen by just drawing a black rectangle, then you effectively have created a memory leak -- eventually your program will crash due to the millions of items that have been drawn.

To clear a canvas, use the delete method. Give it the special parameter "all" to delete all items on the canvas (the string "all"" is a special tag that represents all items on the canvas):

canvas.delete("all")

If you want to delete only certain items on the canvas (such as foreground objects, while leaving the background objects on the display) you can assign tags to each item. Then, instead of "all", you could supply the name of a tag.

If you're creating a game, you probably don't need to delete and recreate items. For example, if you have an object that is moving across the screen, you can use the move or coords method to move the item.

How to delete the canvas from Tkinter after shown the window

Don't need to delete, you can update all of lines:

import tkinter as tk
import random
import numpy as np

class App(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.frame = tk.Frame(self, background="bisque")
        self.frame.pack(side="top", fill="both", expand=True)
        self.canvas = tk.Canvas(self.frame)
        self.line = self.canvas.create_line(100, 100, 300, 200, fill="blue")
        self.canvas.pack(side="top", fill="both", expand=True)
        self.draw_line()

    def remove_line(self, line):
        self.canvas.delete(line)

    def get_h(self):
        h1 = [-1, -0.86, -0.71, -0.57, -0.43, -0.29, -0.14, 0, 0.14, 0.29,0.43, 0.57, 0.71, 0.86, 1]
        map_h = np.linspace(100, 300, 15)
        map_h = np.around(map_h, 3)
        map_h = map_h.tolist()
        rnd_h1 = map_h[h1.index(random.choice(h1))]
        rnd_h2 = map_h[h1.index(random.choice(h1))]

        return rnd_h1, rnd_h2

   def draw_line(self):
        rnd_h1, rnd_h2 = self.get_h()
        self.canvas.coords(self.line, 100, rnd_h1, 300, rnd_h2)
        self.after(1000, self.draw_line)


app = App()
app.mainloop()

Python Overwriting text in Tkinter

To cancel timer. Save return value of after, call after_cancel with saved value.

from Tkinter import *

remain = 11
_timer = None
def cdtimerr():
    global remain, _timer
    remain -= 1
    cdtext = canvas.create_text(510, 6, text=remain, font="Ubuntu 29 bold", anchor=NW) 
    if remain == 0:
        canvas.delete(ALL)
    else:
        _timer = canvas.after(1000, lambda: (canvas.delete(cdtext), cdtimerr()))

root = Tk()
root.geometry('1024x768')
canvas = Canvas(root)
canvas.pack(expand=1, fill=BOTH)
_timer = canvas.after(0, cdtimerr)
Button(root, text='Cancel', command=lambda: canvas.after_cancel(_timer)).pack()
root.mainloop()

Replace Canvas Image in Tkinter

Instead of using Canvas, I replaced the code so that it prints the image using tkinter.Label:

from PIL import ImageTk,Image, ImageFont, ImageDraw
import tkinter
import textwrap
from tkinter import Frame, Canvas, Text, INSERT, END


root = tkinter.Tk()
root.geometry("296x337")
root.resizable(False, False)

img = ImageTk.PhotoImage(Image.open("red.jpg"))
panel = tkinter.Label(root, image=img)
panel.pack(side="bottom", fill="both", expand="yes")

def changepic(imagename):
    img2 = ImageTk.PhotoImage(Image.open(imagename))
    panel.configure(image=img2)
    panel.image = img2


a2=tkinter.Button(root,text='change color',bd=0, command=changepic("blue.jpg")
a2.config(highlightbackground='black')
a2.place(x=135, y=70)

I got my information from: How to update the image of a Tkinter Label widget?

And: https://www.tutorialspoint.com/python/tk_label.htm

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