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pythontkinterpixelmultiple-monitors

Python Tkinter how to adjust the x,y default 0,0 coordinates

I've been learning some basic tkinter and I've come across simple code to centre the window in the middle of your monitor, except when I run it, it's off horizontally. It's pedantic but it bothers me a lot. The code I used

# Imports
from tkinter import *

# tkinter Application
root = Tk()

#Root Geometry
root_Width = 600
root_Length = 600

# Coordinates of top left pixel of application for centred
x_left = int(root.winfo_screenwidth()/2-root_Width/2)
y_top = int(root.winfo_screenheight()/2-root_Length/2)
root_Pos = "+" + str(x_left) + "+" + str(y_top)

# Window size and position
root.geometry(str(root_Width) + "x" + str(root_Length) + root_Pos)

root.mainloop()

Even if I go basic, and just try to open a window the size of my monitor (1920x1080) at 0,0, it's misaligned horizontally by 8px.

from tkinter import *

root = Tk()
root.geometry("1920x1080+0+0")
root.mainloop()

I took a screenshot of the result:
screenshot
I have a dual monitor set up so I've added a red line where the right monitor starts. I don't know what the issue is or how to fix it. If I change it to,

root.geometry("1920x1080+-8+0")

It opens where it should, but I want to fix this in general preferably. I want 0,0 to be the top left pixel of the monitor. I acknowledge the issue may not be with python, but any advice would be helpful.

Solution

  • Ok, there are two thing that you are missing. The first, in your first example, is that you need to assure tkinter is getting the right values, and to do this you have to use update_idletasks() method before any winfo.

    The second thing, which explains why you have to use -8 to center the full screen window, is that tkinter widows have outer-frames. You can determine the size of this frame by checking for the top left coordinate of the window (winfo_rootx()) and of the outer-frame (winfo_x()). Now the frame width is the difference between both: frame_width = root.winfo_rootx() - root.winfo_x() while the real window width is real_width = root.winfo_width() + (2*frame_width), since you have to consider the frame in both sides.

    In summary, to center the window horizontally you do:

    width = root.winfo_width()
frame_width = root.winfo_rootx() - root.winfo_x()
real_width = root.winfo_width() + (2*frame_width)
x = root.winfo_screenwidth() // 2 - real_width // 2

    (here you can print the frame width and you will see it is 8)

    and then use geometry method to place the window at position x.

    Off course you can do the same for the vertical alignment