CODEWITHSUNDEEP
pythontkinter
sgtbp
sgtbp

Reputation: 160

Tkinter window not filling screen in zoomed state on secondary display

I'm building a small python 3 tkinter program on windows (10). From a main window (root) I'm creating a secondary window (wdowViewer). I want it to be full screen (zoomed) on my secondary display. The code below works on my main setup with two identical screens. If I however take my laptop out of the dock and connect it to (any) external display, the new window only fills about 2/3 of the secondary display.

Two things to note: - The laptop and external monitor have same resolution. - The window is appropriately zoomed when overrideredirect is set to 0.

mon_primary_width = str(app.root.winfo_screenwidth()) # width of primary screen

self.wdowViewer = Toplevel(app.root) # create new window
self.wdowViewer.geometry('10x10+' + mon_primary_width + '+0') # move it to the secondary screen
self.wdowViewer.wm_state('zoomed') # full screen
self.wdowViewer.overrideredirect(1) # remove tool bar
app.root.update_idletasks()  # Apply changes

Upvotes: 2

Views: 2029

Answers (1)

sgtbp
sgtbp

Reputation: 160

After two days of experimenting I finally found a fix.

Consider the following example: Making a toplevel zoomed, works fine on any secondary display when using the following code:

from tkinter import *    

# Make tkinter window
root = Tk()
sw = str(root.winfo_screenwidth())
Label(root, text="Hello Main Display").pack()

# Make a new toplevel
w = Toplevel(root)
w.geometry("0x0+" + sw + "+0")
w.state('zoomed')
w.overrideredirect(1)
Label(w, text='Hello Secondary Display').pack()

root.mainloop()

However, in my code I'm making a new Toplevel after running the mainloop command. Then, the issue arises. A code example with the issue:

from tkinter import *

# New Tkinter
root = Tk()
sw = str(root.winfo_screenwidth())

# Function for new toplevel
def new_wdow():
    w = Toplevel(root)
    w.geometry("0x0+" + sw + "+0")
    w.state('zoomed')
    w.overrideredirect(1)
    Label(w, text='Hello Secondary Display').pack()

# Make button in main window
Button(root, text="Hello", command=new_wdow).pack()

root.mainloop()

Problem: The bug is only present if the DPI scaling in Windows is not set to 100%. Hence, there seems to be a bug in how tkinter handles the DPI scaling subsequent to running mainloop. It does not scale the window properly, but Windows is treating it as if it does.

Fix: Tell Windows that the app takes care of DPI scaling all by itself, and to not resize the window. This is achievable using ctypes. Put the following code early in your python script:

import ctypes
ctypes.windll.shcore.SetProcessDpiAwareness(2)

Hopefully others will find the solution helpful. Hopefully, someone may explain more of what is going on here!

Upvotes: 5

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