[英]Why aren't all my widgets showing when I make a new window in tkinter?
[英]tkinter: Why aren't Combobox and Entry widgets deleted by delete("all")?
我的意思是整个小部件而不是里面的文字。 我还尝试在论坛上获得现有解决方案。 我已经剥离了代码以仅显示问题。
我的问题是......当我将ComboBox
和Entry
小部件放在canvas2
上时,它们不会被canvas2.delete("all")
删除。
如果您 select “加权图”,然后从菜单中选择“无向图”,就会出现问题。 在“加权图”之后, ComboBox
和Entry
小部件仍然存在(其他所有内容都按预期删除)。 我设置了时间延迟和一些提示来显示问题。
from tkinter import *
from tkinter import ttk
import time
tk = Tk()
tk.geometry("970x660")
menubar = Menu(tk)
tk.config(menu=menubar)
wrapper1 = LabelFrame(tk, text="Display", height=500)
wrapper2 = LabelFrame(tk, text="Command", width=800)
# canvas was setup to be a vertically scrolling region, I have cut most of that code
# (but my problem does not lie with canvas, that's working fine)
canvas = Canvas(wrapper1, height=500)
canvas.pack(side=LEFT, fill="both", expand="yes")
myframe = Frame(canvas)
canvas.create_window((0,0), window=myframe, anchor="nw", height=500)
# Note: My problem lies on canvas2,
canvas2 = Canvas(wrapper2)
canvas2.pack(side=LEFT, fill="both", expand="yes")
canvas2.update()
wrapper1.pack(fill="both", expand="yes", padx=10, pady=0)
wrapper2.pack(fill="both", expand="yes", padx=10, pady=5)
def DoNothing():
print("Doing nothing!")
def BinaryTree(Weighted, Mode):
canvas.delete("all")
print("Before canvas2.delete...")
canvas2.delete("all")
print("...after canvas2.delete... now waiting 3 seconds so you can inspect if canvas2 is CLEAR... ")
print("...I would expect canvas2 to be clear but Combobox and Entry remain!... ")
canvas2.update()
tk.update()
time.sleep(3)
button1 = Button(canvas2, text = "Add Node", command= lambda: DoNothing(), width=13, anchor=W)
button1_window = canvas2.create_window(20, 40, anchor=W, window=button1)
entry1 = Entry(canvas2, width=10)
entry1.place(x=150, y=40, anchor=W)
button2 = Button(canvas2, text = "Add Edge", command= lambda: DoNothing(), width=13, anchor=W)
button2_window = canvas2.create_window(20, 80, anchor=W, window=button2)
cb1 = ttk.Combobox(canvas2, values=DoNothing(), postcommand=lambda: DoNothing(), width=13, state="readonly")
cb1.place(x=150, y=80, anchor=W)
cb2 = ttk.Combobox(canvas2, values=DoNothing(), postcommand=lambda: DoNothing(), width=13, state="readonly")
cb2.place(x=260, y=80, anchor=W)
if Weighted == True:
canvas2.create_text(380, 80, text="Weight:", anchor=W)
entry2 = Entry(canvas2, width=4)
entry2.place(x=429, y=80, anchor=W)
button3 = Button(canvas2, text = "Delete All Nodes", command= lambda: DoNothing(), width=13, anchor=W)
button3_window = canvas2.create_window(420, 40, anchor=W, window=button3)
canvas2.update()
tk.update()
lmenu = Menu(menubar)
menubar.add_cascade(label="Learning Menu", menu=lmenu)
lmenu.add_command(label="Weighted Graph", command= lambda: BinaryTree(True, "DirectedGraph"))
lmenu.add_command(label="Undirected Graph", command= lambda: BinaryTree(False, "UndirectedGraph"))
while True:
tk.update_idletasks()
tk.update()
time.sleep(0.01)
为什么 Combobox 和 Entry 小部件没有被 delete(“all”) 删除?
这就是 tkinter 设计的工作原理。 canvas delete
方法只删除了canvas个对象。 这意味着,在 canvas 上使用“创建”函数( create_rectangle
、 create_window
等)创建的对象。 对于 window 对象, delete
方法将删除使用 create_window 创建的create_window
object,但它并不是为了删除与 window object 关联的小部件。
与任何小部件一样,要删除实际的小部件,您需要调用小部件本身的destroy
方法。
我的问题是...当我将 ComboBox 和 Entry 小部件放在 canvas2 上时,它们不会被 canvas2.delete("all") 删除。
那是因为当您使用place
时,您并没有创建 canvas 个对象。 要使delete
命令起作用,您必须为组合框和条目小部件调用create_window
。
销毁 tkinter 中的小部件 try.destroy()
f1=tk.Frame()
f1.destroy()
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