Change background in the login screen

Customization
23

I finally understood why it is not enough to replace the image called "login-background.png" in the "/usr/share/themes//gnome-shell" folder with another image of the same name (in .png or .jpg format) to change the background of the GDM login screen in Zorin 17 Core.

The files in the "/usr/share/themes//gnome-shell" directory are just used to define the theme, which is packaged as a special "gnome-shell-theme-gresource" file.

First, you need to get the things in this file. After that, you can make the changes you want (like the background). Finally, you recompile the file.

I've tried to make the task as easy as possible while making sure that the process is easy to understand.


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Open the terminal (Ctrl Alt t).
Note: Select and copy all the lines shown in the code boxes. Press “Ctrl Shift v” to paste them into the terminal, then press “Enter” to execute them.


1. Extract the “gnome-shell-theme-gresource” file

After a few attempts, I think that the “ZorinBlue-Dark” theme needs to be modified for a standard configuration.

cat << 'EOF' > extract.sh
#!/bin/sh

gst=/usr/share/themes/ZorinBlue-Dark/gnome-shell/gnome-shell-theme.gresource
workdir=${HOME}/shell-theme

for r in `gresource list $gst`; do
	r=${r#\/org\/gnome\/shell/}
	if [ ! -d $workdir/${r%/*} ]; then
	  mkdir -p $workdir/${r%/*}
	fi
done

for r in `gresource list $gst`; do
        gresource extract $gst $r >$workdir/${r#\/org\/gnome\/shell/}
done
EOF
chmod +x extract.sh
./extract.sh

2. Choose your image

Put the wallpaper you want (in .png or .jpg format) in the "Pictures" folder.

Paste these three lines into the terminal, replacing “xxxxx” with the name of your wallpaper in the second line.
If your image is in ".jpg" format, also change the four “png” extensions in lines 2 and 3.

sudo cp /usr/share/themes/ZorinBlue-Dark/gnome-shell/assets/login-background.png{,.bak}
sudo cp ~/Pictures/xxxxx.png ~/shell-theme/theme/assets/login-background.png

sudo cp ~/shell-theme/theme/assets/login-background.png /usr/share/themes/ZorinBlue-Dark/gnome-shell/assets/login-background.png

The first line will make a backup copy of the Zorin wallpaper.
The last two lines will rename your wallpaper and copy it to the two locations where it needs to be.


3. Create a “gnome-shell/gnome-shell-theme.gresource.xml” file

This file, which is necessary for compilation, will be placed in the directory “/usr/share/themes/ZorinBlue-Dark/gnome-shell”.

Again, those who have chosen a “.jpg” file will need to change the extension in the line <file>assets/login-background.png</file>.

3. Create a “gnome-shell/gnome-shell-theme.gresource.xml” file

echo "<?xml version="1.0" encoding="UTF-8"?>
<gresources>
  <gresource prefix=\"/org/gnome/shell/theme\">
    <file>assets/activities-dark.svg</file>
    <file>assets/activities.svg</file>
    <file>assets/calendar-event-dark.svg</file>
    <file>assets/calendar-event-today-dark.svg</file>
    <file>assets/calendar-event-today.svg</file>
    <file>assets/calendar-event.svg</file>
    <file>assets/checkbox-dark.svg</file>
    <file>assets/checkbox-focused-dark.svg</file>
    <file>assets/checkbox-focused.svg</file>
    <file>assets/checkbox-off-dark.svg</file>
    <file>assets/checkbox-off-focused-dark.svg</file>
    <file>assets/checkbox-off-focused.svg</file>
    <file>assets/checkbox-off.svg</file>
    <file>assets/checkbox.svg</file>
    <file>assets/gnome-shell-start.svg</file>
    <file>assets/login-background.png</file>
    <file>assets/texture-dark.svg</file>
    <file>assets/texture.svg</file>
    <file>assets/toggle-off-dark.svg</file>
    <file>assets/toggle-off.svg</file>
    <file>assets/toggle-on-dark.svg</file>
    <file>assets/toggle-on.svg</file>
    <file>assets/workspace-placeholder-dark.svg</file>
    <file>assets/workspace-placeholder.svg</file>
    <file>gnome-shell.css</file>
    <file>pad-osd.css</file>
    <file>process-working.svg</file>
  </gresource>
</gresources>" | sudo tee /usr/share/themes/ZorinBlue-Dark/gnome-shell/gnome-shell-theme.gresource.xml> /dev/null

4. Recompile “gnome-shell-theme-gresource” file

sudo cp /usr/share/themes/ZorinBlue-Dark/gnome-shell/gnome-shell-theme.gresource{,.bak}
cd /usr/share/themes/ZorinBlue-Dark/gnome-shell
sudo glib-compile-resources /usr/share/themes/ZorinBlue-Dark/gnome-shell/gnome-shell-theme.gresource.xml


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5. Restart

reboot


Thanks to @Aravisian for the tips, and to the Arch Linux Wiki for the script! :nerd_face:

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