How to clear Tkinter Canvas

Question

When I draw a shape using   canvas create rectangle 10  10  50  50  color  green     Does Tkinter keep track of the fact that it was created    In a simple game I m making  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  and so on    Am I creating thousands of rectangle objects in memory    I know you can assign the code above to a variable  but if I don t do that and just draw directly to the canvas  does it stay in memory  or does it just draw the pixels  like in the HTML5 canvas

User · Answer

Items drawn to the canvas are persistent. create_rectangle returns an item id that you need to keep track of. If you don't remove old items your program will eventually slow down.

From Fredrik Lundh's An Introduction to Tkinter:

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.

User · Answer

Yes  I believe you are creating thousands of objects  If you re looking for an easy way to delete a bunch of them at once  use canvas tags described here  This lets you perform the same operation  such as deletion  on a large number of objects

User · Answer

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

[python] How to clear Tkinter Canvas?

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