Nickel Screensaver

Nickel Screensaver is an addon that brings the transparent screensaver feature to Kobo eReaders, similar to the one on KOReader.

Transparent overlay + book screenshot	Transparent overlay + book cover	Transparent overlay + wallpaper

Preparation

1. Make sure the Kobo screensaver feature is enabled and working

If you haven't enabled it, follow these steps:

1. Connect your Kobo eReader to your computer
2. On the KOBOeReader disk, find the hidden .kobo folder and create a new folder named screensaver
3. Put some small PNG/JPEG photos inside that folder (extensions must be either ".png" or ".jpg")
4. Eject the device safely
5. On your Kobo eReader, go to Settings > Energy saving and privacy and turn on Show book covers full screen
6. Lock the device. You should see a random screensaver.

2. Backup your screensavers in .kobo/screensaver

Every time you lock the device, files in the .kobo/screensaver folder that aren't related to Nickel Screensaver will be moved automatically to .adds/screensaver.

Usually, you don't need to do this step, but it's better safe than sorry.

How to install

⚠️ Requirement: Nickel Screensaver only supports Kobo eReader running firmware 4.21.15015 and later

Make sure to read the Preparation section first. After enabling the Kobo screensaver feature, follow these steps to install:

1. Connect your Kobo eReader to your computer
2. Download the latest KoboRoot.tgz file and place it inside the hidden .kobo folder on your Kobo eReader
3. Eject the device safely

After it installs and reboots, try to lock the screen. If it shows your screensaver, that means it works. If it doesn't, check the Troubleshooting section.

Important

If screensaver images appear in your library, see the Troubleshooting section for the fix.

The file structure before and after installation:

Before	After
.kobo/ ├─ screensaver/ │ ├─ cat.png │ ├─ dog.jpg ├─ KoboRoot.tgz	.adds/ ├─ screensaver/ │ ├─ wallpaper/ │ │ ├─ overlay/ │ │ ├─ cover │ ├─ _settings.ini │ ├─ cat.png │ ├─ dog.jpg .kobo/ ├─ screensaver/

From now on, .adds/screensaver/ is the new location for your screensavers. Don't place them in .kobo/screensaver anymore (but you still need to keep this folder).

One more note: don't unlock the device immediately while it's still in the locking procress, as that may cause a crash and reboot.

How to use

Screensaver images created by Nickel Screensaver have three layers: [1] Overlay layer [2] Color layer (defined in the _settings.ini file) [3] Image layer

	While reading	Other screens
[1]	a random image in .adds/screensaver	a random image in .adds/screensaver/wallpaper/overlay
[2]	Book/ColorOverlay and Book/ColorOverlayAlpha settings	Wallpaper/ColorOverlay and Wallpaper/ColorOverlayAlpha settings
[3]	current page screenshot	a random image in .adds/screensaver/wallpaper

Nickel Screensaver only supports PNG and JPG formats. Make sure your images are small and optimized. Check the Screenshot preparation section for more information.

Settings file

You can change some settings by editing the .adds/screensaver/_settings.ini file.

[Book]
; Color of the Color overlay layer
; In Hex format (default: FFFFFF)
ColorOverlay=ffffff
; Opacity of the Color overlay layer
; Value ranges from 0 to 100 (default: 0)
; Set to 0 to disable the layer
ColorOverlayAlpha=0

[Wallpaper]
; Same as Book.ColorOverlay setting
ColorOverlay=ffffff
; Same as Book.ColorOverlayAlpha setting
ColorOverlayAlpha=0

FAQs

1. Can I still use NickelMenu to toggle the Screensaver feature?
   Yes! Nickel Screensaver won't run when the .kobo/screensaver folder is missing.

2. How many screenshots/screensavers does it keep?
   It only keeps one screenshot/screensaver. Whenever you lock the device, it always overwrites the .kobo/screensaver/nickel-screensaver.jpg file.
   Since version 1.2, Nickel Screensaver no longer writes screensavers into disk. Now it displays them directly from memory.

Screensaver/Wallpaper preparation

Best practices:

1. Images must be in either PNG or JPG format, with .png and .jpg extensions (case-sensitive)
2. A file size under 1 MB is recommended. You can use services like Squoosh to reduce the file size.
3. To avoid unnecessary slowdown, the image dimensions must exactly match your Kobo eReader's screen resolution (for example, it's must be 1072x1448px for Kobo Clara BW). If it doesn't match, Nickel Screensaver will take extra time to scale the unoptimized image first (it does that every time).

   You can check your device's resolution using comparisontabl.es (don't forget to swap the dimensions, e.g., 1448x1072 to 1072x1448)

Resources

• Pre-made screensaver/wallpaper:
  • redphx/ereader-screensaver
  • readerbackdrop.com
  • ereader-related subreddits
• Wallpapers:
  • unsplash.com
  • pexels.com
• Graphic assets:
  • huaban.com
  • nicepng.com
  • cleanpng.com
  • stickpng.com
  • pngall.com

How to disable or uninstall

To temporary disable Nickel Screensaver, simply turn off the Kobo screensaver feature, or rename the .kobo/screensaver folder to something else (you can do this with NickelMenu).

To uninstall, put a file named uninstall in the .adds/screensaver folder, then reboot the device.

Troubleshooting

1. The device doesn't sleep (or reboots) when pressing the Power button

That means there is a bug with Nickel Screensaver. Don't panic, just uninstall it, then report the bug with your device model & firmware version.

2. Screensaver images appear in my library

You need to edit Kobo's setting file to prevent it from scanning hidden folders.

1. Connect your Kobo eReader to your computer
2. Open the .kobo/Kobo/Kobo eReader.conf file with a text editor
3. In the [FeatureSettings] section, replace the line that starts with ExcludeSyncFolders= with the following (insert it if not found):

ExcludeSyncFolders=(\\.(?!kobo|adobe).+|([^.][^/]*/)+\\..+)

4. Save and eject the device safely
5. Reboot the device

Build from source

To build Nickel Screensaver, run the following command:

docker run --volume="$PWD:$PWD" --user="$(id -u):$(id -g)" --workdir="$PWD" --env=HOME --entrypoint=make --rm -it ghcr.io/pgaskin/nickeltc:1.0 all koboroot

Acknowledgements

• Thanks to pgaskin for his NickelHook project
• Thanks to the creators of these projects for their sample code: shermp/NickelClock, tsowell/kobo-btpt