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tkinterraspberry-pifullscreentkinter-canvas

tkinter: fully darken the screen

I want to be able to completely blacken the screen on my Raspberry Pi, on the screen that doesn't have screen dimming as a separate feature. Or to nearly blacken it, drawing something very dimly. To this end, I am creating a full-screen tkinter window and filling it with a canvas, which I can draw black. Almost. I'm getting a one pixel white rim that remains. What is the best way to get rid of this rim, giving me a pure black background?

Here's my test code:

import tkinter as tk

_root = tk.Tk()
_root.withdraw()

def display(win):
    win.create_oval(60,60,210,210,fill="green")

class GraphWin(tk.Canvas):
    def __init__(self, title="Graphics Window"):
        boss = tk.Toplevel(_root)
        boss.attributes('-fullscreen', True)
        tk.Canvas.__init__(self, boss, background = "black")
        self.background = "black"
        self.pack(fill = tk.BOTH, expand=True) # makes it fill the boss area
        boss.lift()
        _root.update()

window = GraphWin()
display(window)
_root.mainloop()

Here's my screenshot, although you'll probably have to download the image to see the white rim distinctively: enter image description here

Solution

  • Used this highlightthickness=0

    Change this:

    tk.Canvas.__init__(self, boss, background = "black")

    to:

    tk.Canvas.__init__(self, boss, background = "black", highlightthickness=0)