CODEWITHSUNDEEP
pythontkinter
user3474688
user3474688

Reputation: 223

Python Tkinter canvas.delete failure

In the experiment below, the tagbox Label should appear when I press the Button1, and it does. But if I follow that with a press on Button2, I get an error referencing a problem in the delete command of the disappear function, then referring to an "invalid boolean operator in tag search expression" in a tk module.

from tkinter import *
from tkinter import ttk

class MainWindow(Frame):
    def __init__(self,master):
        super().__init__()
        self.pack(fill=Y, side=LEFT)
        self.booking_canvas = Canvas(self, width=400, 
        height=100,background="red")
        self.button1 = Button(self.booking_canvas, text = "Appear", command = 
        self.appear)
        self.button2 = Button(self.booking_canvas, text="Disappear", 
        command=self.disappear)
        self.booking_canvas.create_window(20,10,window = self.button1)
        self.booking_canvas.create_window(80, 10, window=self.button2)
        self.booking_canvas.pack(side=LEFT)

     def appear(self):
        self.tagbox = Label(self.booking_canvas,text="Hello")
        self.booking_canvas.create_window(200,10,window = self.tagbox, anchor 
        = NW)

     def disappear(self):
      self.booking_canvas.delete(self.tagbox)

root = Tk()
MainWindow(root)
root.mainloop()

Can you help? I'm not finding the error message very helfpul. I've been able to make the .delete method work in the simple examples I've found in the documentation, but not here.

Upvotes: 1

Views: 972

Answers (1)

falsetru
falsetru

Reputation: 369074

The code should remember the return value of the create_window() call. Then pass it to Canvas.delete method:

def __init__(self, master):
    ...
    self.item = None

def appear(self):
    self.tagbox = Label(self.booking_canvas,text="Hello")
    self.disappear()  # remove old one
    self.item = self.booking_canvas.create_window(200, 10,
        window=self.tagbox, anchor=NW)

def disappear(self):
    if self.item:
        self.booking_canvas.delete(self.item)

Upvotes: 2

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