Python Tkinter Canvas 的边框与由 `create_window' 创建的窗口重叠

Question

I am using tkinter to make a scrolled canvas. When I create a window by create_window link with a frame which is bigger then the canvas, the window will overlap with the border of canvas.

import Tkinter as tk


class ScrollCanvas(object):
    """A widget to show table in frame"""
    def __init__(self, parent=None):
        self.parent = parent
        self.frame = tk.Frame(self.parent, bd=3,
                              relief=tk.GROOVE)
        self.frame.pack(fill=tk.BOTH, expand=1)

        self.frame.grid_rowconfigure(0, weight=1)
        self.frame.grid_columnconfigure(0, weight=1)

        self.xscrollbar = tk.Scrollbar(self.frame, orient=tk.HORIZONTAL)
        self.yscrollbar = tk.Scrollbar(self.frame, orient=tk.VERTICAL)
        self.canvas = tk.Canvas(self.frame, bg='#006666',
                                bd=10, relief=tk.GROOVE,
                                xscrollcommand=self.xscrollbar.set,
                                yscrollcommand=self.yscrollbar.set)

        self.xscrollbar.grid(row=1, column=0, sticky=tk.W+tk.E)
        self.yscrollbar.grid(row=0, column=1, sticky=tk.N+tk.S)
        self.canvas.grid(row=0, column=0, sticky=tk.W+tk.E+tk.N+tk.S)

        self.xscrollbar.config(command=self.canvas.xview)
        self.yscrollbar.config(command=self.canvas.yview)

        self.table = tk.Frame(self.canvas, bd=5, relief=tk.SOLID,
                              width=400, height=200)

        self.canvas.create_window(0, 0, anchor=tk.CENTER, window=self.table)
        self.canvas.update_idletasks()
        self.canvas.config(scrollregion=self.canvas.bbox(tk.ALL))


def main():
    app = tk.Tk()
    app.geometry('400x300')
    frame = tk.Frame(app, width=50, height=50)
    frame.propagate(0)
    frame.pack(fill=tk.BOTH, expand=1)
    mytable = ScrollCanvas(parent=frame)
    app.mainloop()

main()

The result is like this:(the red box)

Does anyone know how to fix this?

Answer 1

Oddly, the canvas border is part of the drawing space, so anything drawn on the canvas has the potential to overlap the borders.

The solution that I use is to remove the border from the canvas, and then put the canvas inside a frame that has a border. Visually it looks the same, but because the visible border belongs to another widget it is impossible for items in the canvas to overlap it.

Answer 2

You can solve that problem by setting the state to be hidden and when it's needed to set it back to normal like this

import tkinter

...
...

canvas = tkinter.Canvas(self, width=100, height=100, bd=0, highlightthickness=0)
canvas.pack()

btn = tkinter.Button(text="Click me", command=print)

win = canvas.create_window(10, 10, anchor=tkinter.NW, window=btn)

canvas.itemconfigure(win, state=tkinter.HIDDEN)

...
...