在 canvas.delete("all") 之后重用 canvas 中的框架小部件不起作用

Question

我在 canvas 中创建了一个框架，我在其中通过单击鼠标放置复选按钮。选择另一个单选按钮运行命令 canvas.delete("all") 以清除 canvas（以及带有复选按钮的框架），然后再次创建框架以继续放置复选按钮。框架已创建，但我无法再放置复选按钮（我也没有收到任何错误消息）。有人知道为什么吗？

from tkinter import *

root = Tk()
top_canvas = Canvas(root,width=676,height=768, bg='light blue')
top_canvas.pack()

frame = Frame(top_canvas, bg='light grey')
main_frame = top_canvas.create_window(500, 780, height = 1600, width = 600, window = frame)

def place_checkbutton_in_canvas(e):  # order to insert the checkbutton
    xx = e.x
    yy = e.y
    buttons = Checkbutton(frame)
    buttons.place(x=xx, y=yy)

def place_checkbutton():  #to run when checkbutton is selected. Now the checkbutton will be placed where mouse clicked if choose_line is selected
    frame.bind('<Button-1>', place_checkbutton_in_canvas)

def clear_canvas():
    top_canvas.delete("all")
    frame = Frame(top_canvas, bg='magenta')
    main_frame = top_canvas.create_window(500, 780, height=1600, width=600, window=frame)

chosen_option = IntVar()
choose_checkbutton = Radiobutton(root, text = "place checkbutton", variable=chosen_option, value = 1, command = place_checkbutton)
choose_checkbutton.place(x=10, y=10)
clear_button = Radiobutton(root, text = "clear everything", variable=chosen_option, value = 2, command = clear_canvas)
clear_button.place(x=10, y=100)

root.mainloop()

Answer 1

不需要删除canvas.You上的所有项目可以使用列表来保存所有选中按钮，并使用.destroy()“删除”它们：

from tkinter import *

root = Tk()
top_canvas = Canvas(root,width=676,height=768, bg='light blue')
top_canvas.pack()
root.checkbutton_list = [] # initial a list

frame = Frame(top_canvas, bg='light grey')
main_frame = top_canvas.create_window(500, 780, height = 1600, width = 600, window = frame)

def place_checkbutton_in_canvas(e):  # order to insert the checkbutton
    xx = e.x
    yy = e.y
    buttons = Checkbutton(frame)
    buttons.place(x=xx, y=yy)
    root.checkbutton_list.append(buttons) # append the checkbutton to the list

def place_checkbutton():  #to run when checkbutton is selected. Now the checkbutton will be placed where mouse clicked if choose_line is selected
    frame.bind('<Button-1>', place_checkbutton_in_canvas)

def clear_canvas():
    for i in root.checkbutton_list:
        i.destroy() # destroy all the checkbuttons in the list
    root.checkbutton_list = [] # init it again

chosen_option = IntVar()
choose_checkbutton = Radiobutton(root, text = "place checkbutton", variable=chosen_option, value = 1, command = place_checkbutton)
choose_checkbutton.place(x=10, y=10)
clear_button = Radiobutton(root, text = "clear everything", variable=chosen_option, value = 2, command = clear_canvas)
clear_button.place(x=10, y=100)

root.mainloop()

如果你真的想和.delete(ALL)一起使用。你需要改变checkbutton.I的父容器使用root.frame覆盖之前的frame.Like:

from tkinter import *

root = Tk()
top_canvas = Canvas(root,width=676,height=768, bg='light blue')
top_canvas.pack()

root.frame = Frame(top_canvas, bg='light grey')
main_frame = top_canvas.create_window(500, 780, height = 1600, width = 600, window = root.frame)

def place_checkbutton_in_canvas(e):  # order to insert the checkbutton
    xx = e.x
    yy = e.y
    buttons = Checkbutton(root.frame)
    buttons.place(x=xx, y=yy)

def place_checkbutton():  #to run when checkbutton is selected. Now the checkbutton will be placed where mouse clicked if choose_line is selected
    root.frame.bind('<Button-1>', place_checkbutton_in_canvas)

def clear_canvas():
    top_canvas.delete("all")
    root.frame = Frame(top_canvas, bg='magenta')
    main_frame = top_canvas.create_window(500, 780, height=1600, width=600, window=root.frame)

chosen_option = IntVar()
choose_checkbutton = Radiobutton(root, text = "place checkbutton", variable=chosen_option, value = 1, command = place_checkbutton)
choose_checkbutton.place(x=10, y=10)
clear_button = Radiobutton(root, text = "clear everything", variable=chosen_option, value = 2, command = clear_canvas)
clear_button.place(x=10, y=100)

root.mainloop()

在 canvas.delete("all") 之后重用 canvas 中的框架小部件不起作用

Reusing frame widget in canvas after canvas.delete("all") doesn't work

python

canvas

tkinter

frame

python-3.x