Launch Steam Desk's "Desktop Mode" from within "Gaming Mode"

desktopmode.sh

#!/bin/bash
#
# Launch Steam Desk's "Desktop Mode" from within "Gaming Mode".
# https://www.reddit.com/r/SteamDeck/comments/wycp1r/comment/ilw1cov/
# https://www.reddit.com/user/FineWolf/
# Friday, August 26, 2022
#
# Commented by Steven Brunwasser
# Sunday, October 23, 2022
#
# Instructions
# ------------
#
# - Save this file to the bin folder in your Home directory: ~/bin
# - Mark the file as executable.
#     - In Dolphin, right-click the file and open Properties.
#       In the Permissions tab, enable the "Is executable" checkbox.
#     - Or, in Konsole, use the following command:
#           chmod +x ~/bin/desktopmode.sh
# - Add the script to Steam as a non-Steam game.
#     - In the Games menu, select "Add a Non-Steam Game to My Library...".
#     - Click "BROWSE..." and navigate to "/home/deck/bin".
#     - Change the "File type" from "Applications (*.desktop)" to "All Files".
#     - Select "desktopmode.sh", click "OPEN", then "ADD SELECTED PROGRAMS'.
# - Give the script a proper name in your Steam library.
#     - Navigate to the "desktopmode.sh" page in your Steam library.
#     - Click on the gear icon and select "Properties...".
#     - Use the first textbox to change the name to "Desktop Mode".
#
# You can use BoilR to give the "Desktop Mode" page proper icons and images
# from SteamGridDB.
#
# - Download and install BoilR from Flathub:
#   https://flathub.org/apps/details/io.github.philipk.boilr
# - Get an API key from SteamGridDB for BoilR.
#     - Sign in to SteamGridDB with your Steam account.
#       https://www.steamgriddb.com/login
#     - Copy the SteamGridDB API key for your account.
#       https://www.steamgriddb.com/profile/preferences/api
#     - In BoilR, go to "Settings" and paste your SteamGridDB API key into
#       the "Authentication key" field. Make sure to check "Download images".
#     - Click the floppy disk icon at the bottom of the window to save.
# - Set the SteamGridDB ID for "Desktop Mode" to download Steam Deck icons.
#   https://www.steamgriddb.com/game/5321601
#     - In BoilR, go to "Images" and click on "Desktop Mode".
#     - Click "Click here if the images are for a wrong game".
#     - Change the "SteamGridDB ID" to 5321601.
# - Set the grid image, hero image, and icon.
#     - In BoilR, go to "Images" and click on "Desktop Mode".
#     - Click on "Grid", "Hero", "Icon", etc. to select images.
#     - When you're done, click on "Import Games".
#     - Click on the button at the bottom of the window with the picture of an
#       arrow pointing from a game controller to the Steam icon to save your
#       changes.
# - Restart Steam to see the new images on the "Desktop Mode" library page.
#

# Exit on any failure.
set -eo pipefail

# Check to make sure we have information about the screen.
if [ -z "${DISPLAY:-}" ]; then
    echo 'No $DISPLAY attached to current session' >&2
    exit 2
fi

# Check to make sure we're running in "Gaming Mode".
# We don't want to launch "Desktop Mode" when we're already in it.
if [ -z "${GAMESCOPE_WAYLAND_DISPLAY:-}" ]; then
    zenity --error --text="This script can only be run in a gamescope session."
    exit 1
fi

# Get information about the screen's resolution.
# We use this to make sure the desktop uses the full screen.
_DISPLAY_RESOLUTION="$(xdpyinfo | awk '/dimensions/ {print $2}')"

# Make sure all shared libraries are loaded in their default order.
unset LD_PRELOAD

# Launch the KDE Plasma desktop environment to enter "Desktop Mode".
exec startplasma-wayland \
    --xwayland --x11-display "${DISPLAY}" \
    --no-lockscreen \
    --width "${_DISPLAY_RESOLUTION%x*}" \
    --height "${_DISPLAY_RESOLUTION#*x}" \
    -- plasma_session