RetroFrame

Turn an old Android tablet into a digital photo frame.

Point it at a folder. It shows your photos. That's the whole app.

retroframe website → · Download v0.2.0 (3.1 MB) →

_{Captured on a 1280×800 tablet emulator. Real-hardware shots welcome.}

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RetroFrame is a free, open source digital photo frame app for Android tablets. It runs a fullscreen photo slideshow from one folder on the device, works entirely offline, and needs no account, no cloud service and no subscription. It supports Android 5.1 and newer, so it revives old tablets that modern photo frame apps have stopped supporting.

Why this exists

There is a drawer in most homes with a tablet in it. It still turns on. The battery is tired, the browser is too old for the modern web, and nobody has touched it in three years. It is not broken — it is just no longer useful.

A tablet is a screen, a power port, and some storage. That is exactly a digital photo frame, and commercial photo frames cost real money to do less.

RetroFrame is built for that device specifically. Not for a flagship phone that happens to also run it — for a 2015 tablet with 1 GB of RAM, a slow eMMC chip, and an Android version that stopped getting updates a long time ago.

That single constraint drives every decision in this project:

• No account. No cloud. No network. The app does not declare the INTERNET permission, so this is enforced by the manifest rather than promised in a README.
• Nothing runs that doesn't have to. No foreground service, no background sync, no push. The folder is watched by a ContentObserver that costs nothing until something changes.
• It has to survive being ignored. The intended use is "plug it in, put it on a shelf, never think about it again." A corrupt JPEG, a missing codec, a folder that vanished — none of them may take down the slideshow.

Features

Slideshow

• Reads any folder you pick, including SD cards and USB storage
• Photos: JPEG, PNG, GIF, BMP, WebP, HEIC
• Videos: MP4, MKV, WebM, AVI, MOV, 3GP — muted by default, played to the end, then advances
• Adjustable interval, 5 seconds to 1 hour
• Fade, slide or zoom transitions
• Pinch-to-zoom on any photo
• Notices photos added to or removed from the folder while running

Favourites

• Tap the heart and that photo comes around about 3× as often
• Spaced out so a favourite never appears twice in a row

Clock mode

• A big, legible fullscreen clock — good for a bedside or kitchen shelf
• Switch manually, or let the sleep schedule do it

Scheduling — what makes it usable as a permanent fixture

• Wake time: turns the screen on and starts the slideshow
• Sleep time: drops to clock mode and releases the screen so it can turn off
• Morning alarm: optional daily alarm with sound, over the lock screen
• Auto-start on boot: survives the inevitable power cut

Deliberately minimal UI

• Fullscreen and immersive — no status bar, no navigation bar, no chrome
• Controls hidden until you tap, then gone again after 3 seconds
• Large touch targets, sized for old low-resolution panels and imprecise digitisers

Privacy

RetroFrame collects nothing, transmits nothing, and has nowhere to send anything.

Network access	None. INTERNET is not in the manifest
Accounts	None
Analytics / crash reporting	None, and none will be accepted — see CONTRIBUTING
Storage access	One folder, chosen by you through the system picker. Read-only
Permissions	Boot, wake lock, alarms, notifications. That is the complete list

Compatibility

Minimum	Android 5.1 Lollipop (API 22)
Target	Android 16 (API 36)
Tested on	Nothing yet — please report what you run it on
Architecture	Any — no native code
RAM	Designed for 1 GB devices
Release APK	~3 MB

Android 5.1 is a deliberate floor: it covers essentially every tablet worth rescuing. Anything older lacks the Storage Access Framework, which is how the app reads your folder without demanding access to all your files.

Install

Download a build

Grab the signed APK from the latest release, copy it to your tablet and open it. You will need to allow installation from unknown sources.

Verify it first if you like — every release lists the APK's SHA-256:

sha256sum retroframe-v0.2.0.apk

Build it yourself

You need Android Studio, or JDK 17 plus the Android SDK.

git clone https://github.com/RobTar97/retroframe.git
cd retroframe
./gradlew assembleDebug          # Windows: gradlew.bat assembleDebug
adb install -r app/build/outputs/apk/debug/app-debug.apk

Distribution channels

Channel	Status
GitHub Releases	Available now — signed APK with a published checksum
F-Droid	Planned. GPL-3.0, no proprietary dependencies, no Play Services — a good fit
Google Play	Under consideration — tradeoffs here
Apple App Store	Not planned. Why not

Setting it up

New to this? → Getting started walks through it with no assumed knowledge. Not sure which tablet? → Choosing a tablet.

The short version:

1. Copy your photos into Pictures on the tablet — over a USB cable (choose File transfer on the tablet, not just charging), or on an SD card. A dedicated subfolder like Pictures/Frame keeps things tidy.
2. Install the APK from the latest release and allow installation from unknown sources when asked.
3. Open RetroFrame. It explains what happens next, then opens Android's folder browser already inside Pictures. Open your folder, tap Use this folder, then Allow.
4. Tap the screen → ⚙ and set the interval, plus wake and sleep times in 24-hour HH:mm. Turn on auto-start so a power cut doesn't leave a black screen.

If Android says "Can't use this folder" you've selected the top level of storage or the Downloads folder. Android blocks both for every app. Open a folder inside, or move the photos into Pictures. Verified: root ❌, Download ❌, Pictures ✅, DCIM ✅.

Physical setup tips

• Heat kills batteries. A tablet permanently charging with a bright screen runs hot, and the battery will swell over months or years. If you can run it without the battery, do. Otherwise use the sleep schedule aggressively and give it airflow.
• Turn the brightness down. Full brightness is rarely needed indoors and is the biggest source of both heat and power draw.
• Disable the lock screen, or the wake schedule lands on it instead of your photos.
• A cheap stand and a right-angle USB cable look dramatically better than a tablet flat against a wall with a cable hanging off it.

Settings reference

Setting	Default	Notes
Seconds per photo	10	5–3600
Shuffle order	on	Off sorts by name, and IMG_2 comes before IMG_10
Include videos	on	Off makes the app noticeably lighter on old hardware
Play video sound	off	Videos are muted unless you enable this
Keep screen on	on	Off lets the device's own display timeout apply
Transition	Fade	Fade, Slide or Zoom
Wake time	disabled	HH:mm, 24-hour
Sleep time	disabled	HH:mm, 24-hour
Morning alarm	disabled	HH:mm, plays the system alarm sound
Auto-start on boot	off	The app must have been launched once first

Favourite weighting applies only when shuffle is on — repeating a photo inside a name-sorted list would just show it three times in a row.

The wake and sleep schedule uses inexact alarms and works everywhere. Only the morning alarm wants exact timing; on Android 12+ the settings screen will tell you if the system is withholding that permission, and offer to take you there.

How it works

Kotlin, Android Views, about 2,000 lines. No Compose, no DI framework, no multi-module setup — each would cost startup time and APK size on a device that has neither to spare.

MainActivity ──── swaps two fragments ────┬── SlideshowFragment (screen kept on)
     │                                    └── ClockFragment     (screen may sleep)
     │
     └── AlarmCompat ──► DailySchedule.AlarmReceiver
                              ├── wake  → wake lock + launch in PHOTO mode
                              └── sleep → launch in CLOCK mode

SlideshowFragment ── ViewPager2 ── SlideshowAdapter ──┬── ImageLoader (Glide) → PhotoView
        │                                             └── SharedPlayer (Media3) → PlayerView
        │
        └── SlideshowViewModel ──┬── PhotoRepository  → one SAF cursor query
                                 ├── PlaylistBuilder  → sort, weight, interleave
                                 └── FolderMonitor    → ContentObserver

Three decisions carry most of the performance:

• The folder is scanned with one cursor query, not DocumentFile.listFiles(). The latter costs an IPC round trip per file per property — about 1,500 calls for a 500-photo folder.
• The folder is watched with a ContentObserver, not a timer. The previous version polled every 10 seconds, forever.
• One video player is shared by the whole slideshow. ViewPager2 keeps offscreen pages alive, so a player per page meant up to three decoder sessions on a device with one decoder.

Full write-up in docs/ARCHITECTURE.md.

Project status

Version 0.2.0 — released, but unproven on real hardware.

The app builds cleanly, R8-minifies to ~3 MB, and passes 30 unit tests plus 14 instrumented tests run on emulators at API 22, 28 and 36 on every push. Version 0.2.0 was a substantial rewrite that fixed a long list of real defects — including a crash on Android 5.1 that had been latent since the beginning, a release build that could never be produced at all, and a folder watcher that hammered the storage provider every 10 seconds.

It still has not run on a physical tablet. CI proves the code executes on Android 5.1; it proves nothing about a 2015 vendor ROM's storage provider, its single hardware video decoder, its power management, or how warm it gets after a fortnight on a shelf. That is the honest state of it, and it is the first entry in docs/KNOWN_ISSUES.md rather than something you find out after installing.

If you have an old tablet, running this and telling us what happened is the most useful thing you can do for the project — more useful than code.

Send a device report →

Roadmap

Towards 1.0

• Signed release and a first GitHub Release
• Verify the rewrite on real hardware across several Android versions
• Recursive subfolder scanning
• Loading indicator while a large folder is scanned
• Video poster frames instead of a flash of black
• Screenshots taken on a real tablet
• F-Droid submission

Later

• Sort by date as well as name
• Per-photo captions
• Translations
• Analog clock face

Explicitly not planned

• Cloud photo services. They need accounts, network access and API keys, and contradict the point of the project.
• Any form of telemetry, even opt-in.
• An iOS version — reasoning.

Documentation

Getting started	Setup for everyone — a simple path and a technical one
Choosing a tablet	Which old devices work, and how to check yours
Architecture	How the code works and why
Known issues	Every current defect, written down
Publishing	Distribution channels and their tradeoffs

Contributing

Contributions are welcome, and device reports count as contributions. The hardware this app targets cannot be bought new and cannot be emulated faithfully, so real-world reports are genuinely the scarce resource here.

See CONTRIBUTING.md to get started and docs/KNOWN_ISSUES.md for what needs doing. By participating you agree to the Code of Conduct.

License

RetroFrame is free software under the GNU General Public License v3.0.

You may use, study, share and modify it. If you distribute a modified version, you must release your changes under the same license. That is deliberate: the project exists to keep old hardware out of landfill, and that goal is not served by someone repackaging it as a closed-source app with ads.

Copyright (C) 2025 RetroFrame contributors

This program is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software Foundation,
either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

Built with

Glide · AndroidX Media3 · PhotoView · AndroidX

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_{Every tablet kept out of a landfill is a small win.}