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App Icon

Wallpaper Changer for Nothing OS

Status Android 13+ Kotlin Compose

A lightweight lock screen wallpaper changer.
Built by a Nothing user, for Nothing users.

Disclaimer: This is an independent, community-made tool. Not affiliated with or endorsed by Nothing Technology Limited.

The "Why"

I love my Nothing Phone (1), but I missed a feature many other OS have: changing the lock screen wallpaper every time I lock the phone.

There weren't many solutions on the Play Store and the ones I found were either outdated, unreliable, or just didn't have the "changing on unlock" feature. As a Computer Science student, I decided to build my own solution that prioritizes performance and user comfort/control.

While optimized for Nothing OS as it has been tested on my Nothing Phone (1), this app works on any device running Android 13+.

Key Features

  • Instant Wallpaper Swap: Each wallpaper is pre-processed and ready to go before you lock your phone resulting in no lag or no loading screens. (Achieved via a disk-buffered pipeline: downsample → crop → WebP.)
  • Wallpaper Collections/Lists: Organize wallpapers in two ways:
    • Folder-based: Point the app at a folder on your device and it picks up all the images inside, with re-sync on demand.
    • Manual: Hand-pick individual photos; they're safely copied into the app's private storage so they're always available.
  • Smart Shuffle: Every image is shown exactly once before the collection reshuffles in order to never getting any individual wallpaper too often.
  • Flexible Cropping: Choose how images fit your screen per collection: center, left-aligned, right-aligned, or fit-to-screen.
  • Rotation Timer Modes: Configure each collection to rotate on every lock, every 1 hour, or once per day.
  • Quick Settings Tile: Start, stop, or check status right from the notification shade letting you control it while doing something else.
  • Default Wallpaper Fallback: Pick a fallback lock screen image that's automatically restored when the service stops or pauses.
  • Survives Reboots: If the service was running before a restart, it picks right back up.
  • Battery Aware: Automatically pauses during Battery Saver and resumes when it's turned off.
  • Self-Healing: If an image can't be loaded (e.g., the file was deleted), the app skips it and moves on.
  • Privacy First: No internet permissions. Your images never leave your device.

Screenshots

Main Screen - Setup Needed Main Screen - Active Collections Grid
Setup Needed Service Active Collections
Create Collection Edit Collection
qs_tile_video.mp4
Create Collection Edit Collection Quick settings tile demo

FAQ

Will this drain my battery?

No. The app doesn't run on a timer or poll in the background, it simply waits for the screen to turn off, then swaps the wallpaper. The actual work (processing one image) takes a fraction of a second. It also automatically pauses during Battery Saver mode.

How much storage does it use?
  • Folder collections: Almost none. The app just references the images where they already are on your device.
  • Manual collections: Images are copied into the app's private storage as compressed WebP files at screen resolution. Expect roughly 0.2–1 MB per image, so a 100-image collection might use around 20–100 MB.
  • A single buffer file (~1 MB) is kept in cache for the next wallpaper. That's it.
Why is there a permanent notification?

Android requires any app doing background work to show a notification, it's a system rule, not a design choice. The notification is as minimal as possible and lets you see the service is running and which collection is active.

Why does it ask to disable battery optimization?

This is optional. Disabling battery optimization helps the app restart reliably after a reboot. Everything else works fine without it, but on some devices the auto-restart after reboot may be less reliable.

The app stopped working / doesn't restart after reboot

While in Nothing OS this shouldn't happen, other phone manufacturers (Xiaomi, Samsung, Huawei, etc.) aggressively kill background apps. Check dontkillmyapp.com for device-specific instructions.

Does this change my home screen wallpaper too?

Currently, the app only changes the lock screen wallpaper. Home screen support may be added in a future update.

Does the app have access to all my photos?

No. When you select a folder, you're granting access to only that specific folder. For manual collections, only the photos you explicitly pick are copied. The app has zero internet permissions, so nothing ever leaves your device.

Installation

For Users

  1. Go to the Releases Page.
  2. Download the latest .apk file.
  3. Install on your Android device (you may need to allow "Install from Unknown Sources").
  4. Grant Permissions: Allow "Notifications" (required to keep the service alive in the background). The app may also ask to disable battery optimization — this improves reliability of the background service and boot-start.
  5. Create a collection: Open the app and create a collection either by selecting a folder or individual photos.

Build from Source

git clone https://github.com/NineCSdev/nothing-wallpaper-changer.git
cd nothing-wallpaper-changer
# Open in Android Studio and sync Gradle
# Requires JDK 17, Android SDK 36
./gradlew assembleDebug        # macOS / Linux
gradlew.bat assembleDebug      # Windows

Architecture

The app follows a clean layered architecture: data (Room + repository), logic (image pipeline), model (entities & enums), service (foreground service + receivers), and ui (single-activity Compose with MVVM).

For the full project structure and design decisions, see docs/ARCHITECTURE.md.

How It Works

  1. User creates a collection (folder or manual) → images are stored in Room.
  2. User presses Start → WallpaperService starts as a foreground service, loads & shuffles the active collection into an in-memory magazine, and pre-processes the first wallpaper into a WebP disk buffer.
  3. Screen turns off → ScreenOffReceiver fires, streams the buffer to WallpaperManager.setStream() on the lock screen flag, then triggers the repository to prepare the next image.
  4. Battery Saver ON → The receiver is unregistered (paused); OFF → re-registered (resumed).
  5. User presses Stop → Service stops; if "revert to default" is enabled, the saved default wallpaper is restored.
  6. Device reboots → BootReceiver checks persisted state and restarts the service if it was previously active.

Tech Stack

Category Library / API
Language Kotlin 2.1 (JVM 17)
UI Jetpack Compose + Material 3
Image loading Coil 2.7
Database Room 2.7 (KSP)
Async Kotlin Coroutines + SupervisorJob
Lifecycle ViewModel + StateFlow / SharedFlow
Min SDK 33 (Android 13)
Target SDK 36 (Android 16)

Permissions

Permission Reason
SET_WALLPAPER Apply wallpapers to the lock screen
FOREGROUND_SERVICE / FOREGROUND_SERVICE_SPECIAL_USE Keep the screen-off listener alive in the background
POST_NOTIFICATIONS Show the required foreground service notification
RECEIVE_BOOT_COMPLETED Restart the service after a reboot
REQUEST_IGNORE_BATTERY_OPTIMIZATIONS Improve reliability of boot-start and background operation

No internet permission is requested — your images never leave your device.

Development Approach

This is my first native Android project, built while actively learning about background services, wallpaper APIs, and system event architecture. I used AI tools as a learning accelerator for understanding unfamiliar Android internals and validating implementation approaches while iterating on the architecture and refining concurrency and system-level decisions.

Status

v0.2-alpha — Core rotation engine, collection management, disk-buffered image pipeline, and Quick Settings tile are functional. The app is under active development.

Author

NineCSdev (CS student @ UPM)

GitHub