car-interface-android

CarDash

A calm, configurable Android car dashboard launcher, built with Flutter.

CarDash replaces the tablet home screen with one landscape page: a large clock, battery and Wi-Fi status, a now-playing media card, and up to 16 buttons — Navigation, Music, optional Jellyfin, Radio, All apps, plus any apps you pin from All Apps. The fixed slots can be shown, hidden and assigned to installed apps; Jellyfin is a built-in music source when configured. Settings opens from the gear next to Wi-Fi. External apps open full-screen using the normal Android launcher mechanism. No overlays, no root, no kiosk setup.

Verified on Android 15 and Android 10 tablet emulators at 1280×800, 1280×720 and 1024×600. Runs on a physical Android 17 HyperOS tablet. OBD-II UI/parser is implemented; the ELM327 socket path still needs a real-car test. Landscape only.

Download

• Gogs release page — published releases
• cardash-android-1.2.0.apk — universal Android release
• SHA-256 and build details: releases/README.md

Gogs limits release attachments to 32 MB, so the 59 MB universal APK is linked directly from the repository.

Screenshots

Light	Dark

Also: Home with top-right Settings · Home at 1024×600 · All apps · app picker · Settings · accent & buttons · Settings · Media access · Now playing · 1280×720 · GPS speed · Update dot · Update dot close-up · Mocked OBD · 1280×720 · Mocked OBD · 1280×800 · Night mode · Blue accent · user-app icon on Home · pinned-app menu · change-icon grid · PIN lock · 1024×600 layout

The two Mocked OBD images are documentation renders with a simulated adapter state (82 km/h, 34% throttle, 7.4 L/100 km, Outside 17°C). They are not live vehicle data.

Features

• One home screen — no pages, no top bar, no bottom dock; information and controls live on the home page.
• Large clock and date with the device's 12/24-hour preference.
• Battery, charging and Wi-Fi status, with one switch to hide the battery level and charging bolt.
• OBD-II car data — optional Bluetooth Classic ELM327 adapter. A dedicated OBD-II Settings card holds the adapter status, paired-device picker and Bluetooth actions. The live card shows speed, a throttle bar and rolling 5 km MAF economy, plus ambient temperature when the adapter provides it.
• Speed card with source choice — Settings → Speed shows or hides the speed card and, while an adapter is selected, chooses OBD-II or GPS. GPS is the fallback when OBD speed is off or unavailable; it reads 0 km/h when stationary, and enabling speed with GPS as the source asks for location permission.
• Temperature row with source choice — Settings → Temperature shows or hides the outside temperature and, while an adapter is selected, chooses OBD-II or GPS + weather. Enabling temperature asks for location permission for the Open-Meteo fallback; if denied, OBD temperature still works. The row reads Outside, 7°C for OBD or Sofia, 7°C for weather, and turns red below 3°C.
• Now-playing media card — the circular ring shows song progress around a play/pause button. The song title and artist scroll along the bottom; paused audio stops the scroll and holds its position. When nothing is playing it reads Nothing playing. The volume slider, −/+, and Mute pill remain.
• Jellyfin — optional music-server integration in Settings → Jellyfin. Turn it on, enter the server URL and pair it with a Quick Connect code; the saved token is reused on later starts. Once configured, turn on the Jellyfin Home button in Settings → General → Home buttons. The tile opens a full-screen dashboard with Recently played, Recently added and Random album rows (six cards when they fit, five otherwise), grouped genre selection and a full album page with track list, previous/next, play/pause and volume. Playback runs in CarDash through Media3, keeps playing in the background, shows a media notification when allowed, pauses on audio-focus loss and reports to Jellyfin. Selecting a Random album re-rolls the row. The home equalizer is exclusive: Jellyfin while it plays, Music only for another app. A rejected token is cleared and asks for pairing again; an unreachable server keeps the token and retries with backoff.
• Update check — on startup, CarDash queries the public Gogs release list without blocking the dashboard. Settings → Updates shows the current version, a Check button, and an Update action that downloads the APK and opens Android’s installer. Android still requires confirmation and a one-time “install unknown apps” allowance; silent installation is not attempted. A small yellow dot appears on the Settings gear whenever an update is available.
• Now-playing access — Settings → Media grants Android notification access, used only to read the active media session’s title, duration and position. CarDash never reads or stores notification content.
• Configurable home buttons — switches in Settings show or hide Navigation, Music, Jellyfin and Radio; the Jellyfin switch is disabled and off until the integration is configured. All apps is always the last button; Settings sits next to Wi-Fi in the top-right status area and is no longer a grid tile.
• Pin any app from All Apps — long-press an app to add it to Home. The home page holds up to 16 buttons including All apps; the grid shrinks as it fills and stays anchored to the bottom edge.
• Edit a pinned app — long-press it on Home for Rename, Change icon and Remove. Pinned apps show their own icon by default. Rename changes only the Home label; Change icon offers Default plus 29 monochrome line icons (white on dark, black on light); Remove takes effect without confirmation. Re-add the app from All Apps.
• One-time launcher tip — the first run shows a short notification that the default-launcher setting lives in Settings. It is not shown again.
• All apps — searchable grid of every launchable app, launched full-screen.
• Media-aware Music and Jellyfin tiles — the stylized music icon shows a small animated equalizer while another app is playing; the Jellyfin tile shows it only while CarDash's Jellyfin player is playing. The two are mutually exclusive. Android exposes media-active state, not the playing package, to a normal launcher; Jellyfin is known because CarDash owns that player. The tile labels are clipped to the rounded button width so long album names cannot widen the grid.
• Six accent colors — Green, Blue, Amber, Rose, Violet or Teal, applied across the whole interface.
• Prevent CarDash from sleeping — a Settings switch, on by default. Turn it off to use the system display timeout.
• Night mode — long-press an empty part of the Home background to go black with a very dim centered clock; tap anywhere to return. Long-presses on buttons and cards are unaffected.
• A short onboarding hint — the long-press hint is visible only during the first ten minutes after a fresh installation, then stays gone. Upgraded installs do not see it again.
• Light / Dark / Automatic theme. Automatic uses a fixed local-time window (default 19:00–07:00), editable in Settings.
• Optional PIN — four digits, stored as a salted PBKDF2 hash in Keystore-backed storage. It is requested only when the launcher process cold-starts, never when returning from an app.
• Standard Android home role — no overlay, kiosk or root.
• Android 10+, landscape-only, tablet-first (verified at 1280×800).
• No CarDash accounts, no telemetry, no T&C screen. Network access is used only for the optional Open-Meteo temperature fallback, the Jellyfin server you configure (library, artwork and audio), and the public release check.

Requirements

• Flutter 3.47.8 / Dart 3.13.7 (or a compatible newer stable release)
• Android SDK 36, build-tools 36
• JDK 21 for Gradle (the machine default is JDK 27, which is not validated)
• Android 10 (API 29) or newer device/emulator
• A landscape tablet or an emulator; the app locks itself to landscape
• The prepared tablet AVDs use the host GPU; a working GPU driver is recommended
• Optional: a Bluetooth Classic ELM327 adapter already paired in Android
• Optional: location access for the Open-Meteo temperature fallback
• Optional: a Jellyfin 12.x server and account for the built-in music source

The Android application ID is com.wasp.cardash_launcher. Android package segments cannot contain hyphens, so the requested com.wasp.cardash-launcher spelling is normalized to an underscore.

export JAVA_HOME=/usr/lib/jvm/java-21-openjdk
export ANDROID_HOME=/opt/android-sdk
export PATH="$ANDROID_HOME/platform-tools:$PATH"

Quick start

flutter pub get
./tool/check.sh

# Boot the prepared 10.1" 1280×800 Android 15 tablet (headless)
./tool/emulator.sh 35

# Build, install, and make CarDash the HOME app
./tool/install.sh debug

If the emulator does not yet exist on another machine, create it with:

sdkmanager "system-images;android-35;google_apis;x86_64"
avdmanager create avd -n cardash_tablet_api35 \
  -k "system-images;android-35;google_apis;x86_64" \
  -d "10.1in WXGA (Tablet)"

The repository also has an Android 10 AVD (cardash_tablet_api29) for minimum-version checks.

Manual install

flutter build apk --release
adb install -r build/app/outputs/flutter-apk/app-release.apk
adb shell cmd role add-role-holder android.app.role.HOME com.wasp.cardash_launcher
adb shell am start -a android.intent.action.MAIN -c android.intent.category.HOME

On a real tablet, use Settings → General → Home app → Set as default and accept the system prompt. Android will not let an app force itself into the home role silently. CarDash no longer keeps a home-role banner on the dashboard; the first run shows a one-time tip pointing to this setting.

Using CarDash

Action	Result
Tap Navigation / Music / Radio	Open the assigned app full-screen
Tap Jellyfin	Open the Jellyfin dashboard (Albums)
Long-press Navigation / Music / Radio	Pick a different installed app
Long-press Jellyfin	Nothing; Jellyfin is a built-in source
Tap an unassigned shortcut	Open the app picker
Settings → Accent	Pick Green, Blue, Amber, Rose, Violet or Teal
Settings → Battery & charging	Show or hide battery level and charging bolt
Settings → Prevent CarDash from sleeping	Keep the display on, or use the system timeout
Long-press an empty part of Home	Enter black night mode with a dim clock
Tap the night screen	Return to the dashboard
Settings → Home buttons switches	Show or hide Navigation, Music, Jellyfin, Radio
Settings → Jellyfin → Allow	Enable the media notification on Android 13+
Jellyfin dashboard → album	Start the album and open its track list
Jellyfin dashboard → Random → album	Start it and re-roll the Random row
Long-press an app in All Apps	Add it to Home (up to 16 buttons)
Long-press an added app on Home	Rename, Change icon or Remove
Settings → OBD-II	Pick a paired ELM327 or None; open Bluetooth settings
Settings → Speed	Show or hide the speed card; choose OBD-II or GPS source
Settings → Temperature	Show or hide the temperature row; choose OBD-II or GPS + weather
Speed card	OBD-II when connected, otherwise GPS; 0 km/h when stopped
Temperature row	OBD ambient, or location weather when OBD is off/unavailable
Settings	Theme, accent, media access, battery, home buttons, OBD/speed/temperature, default-home role, PIN
All apps	Search every launchable app; tap to open, hold to pin
Music tile while another app plays	Shows the selected app icon + equalizer
Jellyfin tile while Jellyfin plays	Shows the headphones icon + equalizer
Circular ring	Song progress; tap the centre to play/pause
Song title at the card bottom	Scrolls only while playing; holds when paused
Screen	Stays awake while CarDash is in front
Mute pill	Toggle media mute
Slider or − / +	Set media volume
Hardware volume keys	Adjust the dashboard's media volume; the slider follows
Long-press Media volume	Show/hide raw volume diagnostics while troubleshooting a car unit

The app hides the Android status and navigation bars while CarDash is in the foreground. Swipe from an edge to reveal them temporarily; they hide again when the app resumes.

Settings

General

• Light / Dark / Auto theme.
• Accent: Green, Blue, Amber, Rose, Violet or Teal.
• Battery & charging: one switch hides both the level and charging bolt.
• Prevent CarDash from sleeping: keep the display on; on by default.
• Auto night window (default dark from 19:00, light from 07:00).
• Home buttons: show/hide Navigation, Music, Jellyfin, Radio; live count out of
  1. Jellyfin is disabled and off until configured.
• Assign the app for Navigation, Music and Radio; Jellyfin is built-in, and All apps is fixed and last.
• Settings is always available from the gear next to Wi-Fi.
• Home role status and shortcut to the system prompt.

Media

• Notification access for the now-playing title, duration and progress.
• Read-only: CarDash does not read notification content.
• Without access the ring stays empty and the card shows a generic Playing / Nothing playing state.

Jellyfin

• One switch enables the optional integration. While it is off, CarDash never contacts a Jellyfin server.
• When enabled and not connected, enter the server URL (https://host, host:port or a path such as https://host/jellyfin) and press Connect.
• Without a saved pairing, the card shows a Quick Connect code. Open Jellyfin, choose Quick Connect, enter the code and approve it there.
• A saved pairing is reused on later starts; the card shows the server name and the signed-in user. Remove pairing clears it and turns the switch off.
• A rejected token turns the switch off, clears the token and offers Pair again.
• Without a network the card shows No internet — retrying and retries with backoff until the server is reachable again.
• Random genres: choose up to five grouped families (Metal, Rock, Jazz, Pop, Folk and so on) in the Jellyfin card. Raw tags such as Метъл, Рок, Melodic metal and Pop-Rock are grouped into those families. If none are selected, the dashboard asks you to choose genres in Settings.
• Home button: after pairing, turn on Jellyfin in Settings → General → Home buttons. The tile sits after Music and before Radio and opens the dashboard.
• Dashboard: Recently played (derived from played tracks across your Jellyfin devices), Recently added, and Random. Artists is shown but disabled for a later release. Six albums per row when they fit, otherwise five.
• Album page: large cover, track list, previous / play-pause / next, current track and the same volume/mute controls as Home.
• Playback: in-app Media3 with background playback, a media notification on Android 13+ when allowed, audio-focus pause/resume, and playback reporting to Jellyfin. Stops at the end of the album; no autoplay or repeat.
• Allow notifications asks for Android's notification permission; denying it only hides the playback notification, not playback itself.

OBD-II

• Adapter dropdown: None plus paired Bluetooth Classic devices that look like OBD-II adapters. Show all paired devices reveals phones, headsets and other bonded devices for unusual adapters.
• Connection status and a Find/Allow action for Bluetooth permission.
• If Bluetooth is off: Open Bluetooth settings to turn it on, then return. CarDash checks the adapter state and reuses the cached device list instead of querying the Bluetooth stack on every resume.
• Connection attempts are bounded. After three failures the card shows Retry connection instead of retrying forever.
• Read-only note: CarDash never writes to the ECU. Adapter settings only; speed and temperature choices live in their own cards.

Speed

• One switch shows or hides the speed card on Home.
• While an OBD-II adapter is selected, Use OBD-II for speed selects the source. Off means GPS is used.
• Without OBD (or with OBD speed off), the GPS fallback is used. Enabling speed or switching the source to GPS asks for location permission; if denied, the switch stays on and a message explains why. It reads 0 km/h when stationary.

Temperature

• One switch shows or hides the outside-temperature row below the clock.
• While an OBD-II adapter is selected, Use OBD-II for temperature selects the source. Off means GPS + the Open-Meteo weather provider is used.
• Enabling temperature or choosing the weather source asks for location permission and refreshes every 15 minutes. If permission is denied, OBD temperature still works when available.
• The row turns red below 3°C and hides when no fresh value exists.

Updates

• Non-blocking check against the public Gogs releases.
• Shows current/latest version; Update downloads the APK and opens Android’s installer.
• Android confirms the install and, on first use, asks to allow CarDash as an unknown-app source. No silent installation.

Security

• Set, change or remove a four-digit PIN.
• The PIN is requested only on a cold start. It does not re-lock when switching apps, after screen-off, or after returning from Navigation. This is the agreed behavior, not an oversight.
• The PIN protects the launcher UI. It is not the Android lock screen; set a device screen lock separately for device-level security.
• There is no PIN recovery. Resetting app data removes it.

Architecture

lib/
  core/        design tokens, theme controller, icons, shared widgets
  data/        models, platform services, SettingsRepository (single source of truth)
  features/
    home/      home page, shortcut grid, volume card, OBD/weather controllers
    apps/      All Apps, app-picker sheet
    settings/  General, OBD-II, Speed, Temperature + Security
    lock/      PIN pad, cold-start lock screen
android/...    MainActivity, LauncherBridge, SystemBridge, TelemetryBridge, ObdService
tool/          emulator, install, check scripts
docs/          implementation plan, design notes

• Flutter owns all UI. Kotlin exposes package enumeration/launching, the HOME role, battery/Wi-Fi, media volume, active media metadata, Bluetooth OBD and one-shot location over method channels.
• The OBD layer is read-only, Bluetooth Classic SPP, bonded devices only. A worker thread serializes ELM327 requests; Flutter polls the latest snapshot.
• SettingsRepository is the only persistence path. Controllers are ChangeNotifiers injected with provider.
• External apps are separate activities; Android has no public API to embed them inside the launcher. This app deliberately accepts full-screen launching for maximum compatibility.
• Full OBD/weather design and hardware notes: docs/OBD_TEMPERATURE.md.

Testing

flutter analyze
flutter test
./tool/check.sh

The 134 tests cover PIN hashing/persistence, settings persistence, theme/accent, dark accent tinting, battery visibility, first-run state, the ten-minute onboarding hint, slot visibility, pinned apps, custom labels/icons, the 16-button cap at 1280×800, 1280×720 and 1024×600, the dense shortcut grid, the equalizer animation, OBD economy, the OBD card, media-key playback, media metadata/progress, the marquee, the play/pause ring, fixed-volume handling, volume-write diagnostics, the keep-awake preference, the night overlay, GPS speed fallback and its permission prompt, speed/temperature source persistence, weather fallback, the update version/availability logic and the Settings update dot. Jellyfin coverage includes genre grouping, recent-played dedupe, the 12.2 request contract, the dashboard controller and widget states, the genre picker and five-family cap, album page/track list/transport, playback queue and state mapping, the settings gating and the Home tile width clipping. Native package enumeration, the HOME role, volume, app launching and PIN flows were verified on API 35 and API 29 emulators. Location permission, reverse geocoding and the Open-Meteo fallback were verified live on the API 35 emulator. Now-playing title, artist, progress and pause/resume were verified against a live Chrome MediaSession. Jellyfin was verified end-to-end on API 34 against a real 12.2 server (Quick Connect, grouped genres, 6/5-card dashboard, album page, background playback, notification, media keys, exclusive equalizers, audio-focus handover, Random re-shuffle) and against a local 12.2 container. The OBD hardware path compiles and is covered by the parser/economy design, but no ELM327 adapter is available on this machine; socket behavior still needs a car test. The 1.2.0 universal APK is built from this tree and published. The emulator has verified the in-app update path.

Troubleshooting the emulator

The prepared AVDs use the host GPU (-gpu host), which is the verified setup on this machine. Software rendering with SwiftShader segfaulted on the API 35 image. If your machine has no usable GPU, you can try:

CARDASH_GPU=swiftshader_indirect ./tool/emulator.sh 35

The prepared AVD resolution is 1280×800. If the emulator is already running, ./tool/emulator.sh stop shuts it down before starting a different one. The Android 15 AVD is left running headlessly after development; use ./tool/emulator.sh 35 window for a visible window.

Compatibility and limitations

• minSdk 29 (Android 10); compile/targetSdk 36. Nothing in the design requires a newer Android release.
• Landscape only (sensorLandscape). The home page is designed for 1280×800 and verified at 1280×720 and 1024×600; 16 buttons fit at all three.
• 16-button cap includes All apps; Settings lives in the top-right status area and does not consume a slot. Only apps pinned from All Apps show an original app icon by default; the predefined slots, All apps and the Settings gear stay stylized. A pinned icon can be replaced with the Default app icon or the 29 stylized choices.
• Accent-tinted dark theme — dark canvas, surfaces and borders blend toward the selected accent, so Blue no longer shows a green base.
• Media equalizer reacts to system media activity. The now-playing title and progress use the active Android MediaSession, which requires the special notification-access grant in Settings → Media.
• Notification access is used only for media metadata. CarDash does not read notification text or store track history. Revoke it in Android settings at any time; the ring and title then fall back to an empty/generic state.
• Volume control writes the media stream. If Android reports a fixed-volume policy (common on car head units), the vehicle amplifier owns the level; CarDash disables the slider and explains why. Otherwise, if a unit ignores absolute volume writes, CarDash falls back to the same relative steps as the hardware volume keys.
• Volume diagnostics — long-press the Media volume label to show the raw index/max, fixed-volume flag, every stream level, and the target/actual of the last write. The same values are logged under the CarDashVolume logcat tag.
• Screen-on is controlled by Settings → Prevent CarDash from sleeping (default on). It applies only while CarDash is the foreground window; with the switch off, the normal Android display timeout applies.
• Night mode is a display overlay only. It does not change panel brightness or keep the screen awake by itself; the screen-on preference still applies. Long-press on cards and buttons is reserved for their own actions.
• Onboarding hint is anchored to the first launch after a fresh install and disappears after ten minutes. It is migrated to expired for upgraded installs and never returns.
• No embedded third-party app UI. Navigation/Music/Radio are launched in their own full-screen windows. Jellyfin is the exception: its music library and player are a first-party CarDash dashboard, because it is an API/music source rather than an embedded app.
• Renaming changes the Home label only. Android does not allow a launcher to rename another app's installed label.
• Custom icons are bundled monochrome SVGs, so they follow the light/dark theme. Default restores the pinned app's own icon.
• Play/pause uses the Jellyfin player when it is active, otherwise Android media keys. With no active session it opens the app assigned to the Music slot (or asks you to choose one). The ring shows Play whenever the selected source is paused/inactive.
• Updates download and invoke Android’s installer. CarDash never silently installs. Android requires the user to confirm each install and, once, to allow CarDash as an unknown-app source.
• Song progress/title for other apps require notification access. Without it, Android does not expose MediaSession metadata to a normal launcher; the card still controls playback and shows Nothing playing or Playing. Jellyfin's own title/progress come from CarDash's player and work without it.
• Jellyfin is online-only in 1.2.0. There is no offline library cache or download. An unreachable server shows an inline Retry state; selected genres and the token persist. The Artists tab is disabled for a later release.
• Jellyfin genre grouping is heuristic. Built-in family rules group known raw tags (including Cyrillic aliases); unusual tags become standalone families. The picker is capped at five families.
• Jellyfin notification permission is optional. On Android 13+, allow it in Settings → Jellyfin to see the playback notification. Playback continues without it; the Home card and dashboard still control the player.
• Jellyfin drives the car audio focus. It pauses on a permanent focus loss (another music app) and stays paused; a short transient loss (navigation prompt) resumes only if it was playing. It stops at the end of the album.
• Speed source is selectable only while an OBD adapter is selected. GPS fallback requires fine location and the GPS provider enabled; enabling speed with GPS as the source asks for location permission. Stale/no-fix GPS values are hidden.
• OBD-II is a subset: Bluetooth Classic SPP only, paired devices only, read-only. Speed, throttle, MAF economy and ambient temperature are implemented; RPM, coolant, voltage, MIL/DTCs, fuel level and BLE/Wi-Fi adapters are not. The adapter list is class/name filtered, and connections stop after three failures so an absent adapter cannot keep the Bluetooth stack busy.
• Temperature source is selectable only while an OBD adapter is selected. Weather fallback uses Open-Meteo and the device location; it requires location permission and network access, and hides the row when unavailable.
• Location data is not stored. Only the selected adapter address, the speed/temperature choices, the weather preference, the Jellyfin URL and the selected genre families are persisted. The Jellyfin access token is kept in Keystore-backed storage.
• QUERY_ALL_PACKAGES is used to list all launchable apps. It is reasonable for a launcher but requires a Play policy declaration if the app is ever distributed; this is a local/sideload build for now.
• Network access is used for the optional Open-Meteo temperature fallback, the Jellyfin server you configure (library, artwork and audio) and the Gogs release check. There are no CarDash accounts, ads, telemetry or silent auto-updates.
• The launcher cannot replace Android's lock screen. The PIN does not protect a running session, by design.

Design

The visual language is inspired by the TrailCurrent Godwit head unit (MIT): warm neutral surfaces, a selectable instrument accent, large numerals and quiet line icons. It is not a copy of that UI.

• Typeface: Manrope (SIL Open Font License), bundled offline.
• Icons: Lucide (ISC), bundled as SVGs.
• Palette and tokens: lib/core/theme/app_colors.dart.

Roadmap

• Optional compact now-playing control beside the volume card.
• Real-car ELM327 soak test (speed/throttle/MAF/ambient).
• Release signing configuration.
• Real-device soak test on an Android 10 car tablet.

License

This repository is in local development and has not been pushed or published. A project license has not been chosen yet. Third-party asset licenses: Manrope (OFL) and Lucide (ISC). The design is inspired by TrailCurrent Godwit (MIT).