Change back DPI settings in a bash script - bash

Question

I would like to run a program that does not properly support my desired resolution+DPI settings.
Also I want to change my default GTK theme to a lighter one.
What I currently have:
#!/bin/bash
xfconf-query -c xsettings -p /Xft/DPI -s 0
GTK_THEME=/usr/share/themes/Adwaita/gtk-2.0/gtkrc /home/unknown/scripts/ch_resolution.py --output DP-0 --resolution 2560x1440 beersmith3
This sets my DPI settings to 0, changes the gtk-theme, runs a python script that changes my resolution and runs the program, and on program exit changes it back. This is working properly.
Now I want to change back my DPI settings to 136 on program exit
xfconf-query -c xsettings -p /Xft/DPI -s 136
My guess is I need to use a while loop but have no idea how to do it.
ch_resolution.py
#!/usr/bin/env python3
import argparse
import re
import subprocess
import sys
parser = argparse.ArgumentParser()
parser.add_argument('--output', required=True)
parser.add_argument('--resolution', required=True)
parser.add_argument('APP')
args = parser.parse_args()
device_context = '' # track what device's modes we are looking at
modes = [] # keep track of all the devices and modes discovered
current_modes = [] # remember the user's current settings
# Run xrandr and ask it what devices and modes are supported
xrandrinfo = subprocess.Popen('xrandr -q', shell=True, stdout=subprocess.PIPE)
output = xrandrinfo.communicate()[0].decode().split('\n')
for line in output:
# luckily the various data from xrandr are separated by whitespace...
foo = line.split()
# Check to see if the second word in the line indicates a new context
# -- if so, keep track of the context of the device we're seeing
if len(foo) >= 2: # throw out any weirdly formatted lines
if foo[1] == 'disconnected':
# we have a new context, but it should be ignored
device_context = ''
if foo[1] == 'connected':
# we have a new context that we want to test
device_context = foo[0]
elif device_context != '': # we've previously seen a 'connected' dev
# mode names seem to always be of the format [horiz]x[vert]
# (there can be non-mode information inside of a device context!)
if foo[0].find('x') != -1:
modes.append((device_context, foo[0]))
# we also want to remember what the current mode is, which xrandr
# marks with a '*' character, so we can set things back the way
# we found them at the end:
if line.find('*') != -1:
current_modes.append((device_context, foo[0]))
for mode in modes:
if args.output == mode[0] and args.resolution == mode[1]:
cmd = 'xrandr --output ' + mode[0] + ' --mode ' + mode[1]
subprocess.call(cmd, shell=True)
break
else:
print('Unable to set mode ' + args.resolution + ' for output ' + args.output)
sys.exit(1)
subprocess.call(args.APP, shell=True)
# Put things back the way we found them
for mode in current_modes:
cmd = 'xrandr --output ' + mode[0] + ' --mode ' + mode[1]
subprocess.call(cmd, shell=True)
edit:
Thanks #AndreLDM for pointing out that I do not need a separate python script to change the resolution, I don't know why I didn't think of that.
I changed it so I don't need the python script and it is working properly now. If I can improve this script please tell me!
#!/bin/bash
xrandr --output DP-0 --mode 2560x1440
xfconf-query -c xsettings -p /Xft/DPI -s 0
GTK_THEME=/usr/share/themes/Adwaita/gtk-2.0/gtkrc beersmith3
if [ $? == 0 ]
then
xrandr --output DP-0 --mode 3840x2160
xfconf-query -c xsettings -p /Xft/DPI -s 136
exit 0
else
xrandr --output DP-0 --mode 3840x2160
xfconf-query -c xsettings -p /Xft/DPI -s 136
exit 1
fi