How to I clear Tkinter Canvas using Python

Question

When I draw a shape using:

canvas.create_rectangle(15, 15, 60, 60, color="blue")

Does Tkinter keep track of the fact that it was created?

I am making a game where my code has one Frame create a bunch of rectangles and then draw a big black rectangle to clear the screen and then draw another set of updated rectangles.

Am I creating thousands of rectangle objects in memory? What is the right way to do it? Appreciate some help here!

Answer 1

To clear a canvas, use the delete method. 

This ensures you avoid memory leaks and not end up creating thousands of objects.

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")

Hope this helps!!

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Thanks!

Comments

can I add widgets to it after using this code 

canvas.delete("all"). 

What I did is, I created a button, if it is clicked it creates a new screen(basically just deletes everything off the canvas), can I add widgets to that blank canvas?

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Hi, @There,

Yes, you can add widgets,

To display things on the canvas, you create one or more canvas items, which are placed in a stack. By default, new items are drawn on top of items already on the canvas.

Tkinter provides lots of methods allowing you to manipulate the items in various ways. Among other things, you can attach (bind) event callbacks to individual canvas items.

To draw things in the canvas, use the create methods to add new items.

from Tkinter import *

master = Tk()

w = Canvas(master, width=200, height=100)
w.pack()

w.create_line(0, 0, 200, 100)
w.create_line(0, 100, 200, 0, fill="red", dash=(4, 4))

w.create_rectangle(50, 25, 150, 75, fill="blue")

mainloop()

Note that items added to the canvas are kept until you remove them. If you want to change the drawing, you can either use methods like coords, itemconfig, and move to modify the items or use delete to remove them.

i = w.create_line(xy, fill="red")

w.coords(i, new_xy) # change coordinates
w.itemconfig(i, fill="blue") # change color

w.delete(i) # remove

w.delete(ALL) # remove all items