A clean, minimal Android home-screen launcher for car head units — the cheap
aftermarket "Android radio" double-DIN units, not Android Auto.
Kotlin, classic Views, landscape-first with a portrait layout for upright
screens, no Google Play Services required,
and it runs all the way back to Android 4.4 (KitKat) so it works on old units too.
The whole launcher is one screen. A status bar across the top, two panels below it, and a tab bar along the bottom.
The top bar holds a Home button, five quick-launch favourites, and a Wi-Fi indicator that only appears when the unit is connected. Tap an empty favourite slot to assign an app, long-press one to change or clear it.
The left panel is the clock and weather: a large clock and date, current conditions, and a three-day forecast. The clock face can be digital, analog or minimal, and an optional stopwatch sits under it.
The right column is two cards, and both are yours to fill. Either one can be:
- the media player — album art, title and artist read from whatever app is actually playing, with play/pause, skip, a scrubbable seek bar and volume;
- the phone shortcut;
- a row of app shortcuts you choose;
- up to three Android home-screen widgets, hosted for real — the same widgets you'd put on a phone's home screen.
The bottom tabs are Audio, Radio, Phone, Nav, Apps and Settings, each mapped to an app you pick. They can be reordered, and any of them except Apps and Settings can be hidden — those two stay because they're the only way back into the launcher's own screens.
Settings → Customize home screen is a live editor: it inflates the real dashboard, so what you're dragging is exactly what you'll get. Drag the bar between the cards to resize them, swap their order, and choose what each one holds.
| Colour themes | Tab editor |
|---|---|
 |
 |
Portrait units stack the panels and fill the space underneath with the app drawer. It doesn't scroll: it measures the room it has, works out how many rows fit, and pages the rest — swipe across the icons or tap a dot to change page. Reaching for a scrollbar while driving is worse than a swipe.
Dashboard
- Large clock and date, current weather, and a 3-day forecast
- Digital, analog or minimal clock face, plus an optional stopwatch
- Live media panel: album art, title/artist, play-pause, next/previous, volume, and a scrubbable seek bar with elapsed/total times
- Controls drop out in order as a card shrinks, rather than being squashed
- Two configurable cards: media player, phone, app shortcuts, or app widgets
- Quick-launch dock of 5 favourite apps in the top bar
- Wi-Fi indicator (only shown when connected)
- Six tabs: Audio · Radio · Phone · Nav · Apps · Settings
App widgets
- Any installed home-screen widget can be hosted on either card, up to three side by side
- Add, swap and remove them from the Customize screen, or by long-pressing the card itself
- Widgets that need a configuration step get one, and are told their real size so they pick the right layout
App drawer
- Live search
- "Frequently used" strip based on your own launch history
- Long-press any app to hide it from the drawer
- Refreshes automatically when apps are installed or removed
- On portrait units, a paged drawer sits on the home screen itself
Appearance
- 7 colour schemes — Midnight, Ocean, Sunset, Forest, Violet, Crimson, Graphite — each applying a gradient and matching accent across the whole UI, icons included
- Light and dark palettes; dark by default, with Auto (by time of day), Light, and Follow-system options
- Runs fullscreen with the system bars hidden, using its own in-app Back/Home navigation on every screen
Staying up to date
- The sideloaded build checks GitHub Releases for a newer version, at most once a day, and offers it with its release notes — Update now, Later, or Skip this version. Skipping is remembered per version, so it never hides a later one
- It downloads the APK and hands it to the system installer, so there's no hunting for a browser on a unit that may not have one
- Settings → About shows the version and build number, and checks on demand: it answers either way, rather than leaving "no prompt" to mean both you're current and the check never ran
- Only in the sideloaded build. The Play version updates through Play, and the two are signed with different keys, so neither could install the other
Setup and settings
- Guided first-run setup: language, default apps, permissions, and a prompt to become the default launcher
- Everything re-configurable later in Settings
- 10 languages: English, Turkish, Spanish, German, French, Italian, Portuguese, Russian, Simplified Chinese, Arabic (with RTL support)
| Min Android | 4.4 KitKat (API 19) sideloaded · 5.0 (API 21) via Play |
| Target Android | 16 (API 36) |
| Orientation | Landscape and portrait |
| Google Play Services | Not required |
| API keys | None |
Designed for common head-unit resolutions — 1024×600 and 800×480 both work, and upright screens get their own stacked layout.
Grab the APK from the latest release and sideload it:
adb install -r dashline-v0.1.4.apkOr copy the APK to a USB stick, plug it into the head unit, and open it with the unit's file manager.
After that first install, the app offers its own updates: it checks GitHub once a day and can download and install a new release for itself. Android asks you to allow it to install packages the first time.
Open the project in Android Studio (Giraffe or newer). It will fetch the right Gradle and SDK versions and generate the Gradle wrapper on first sync.
Then, from the command line:
./gradlew assembleDebug./gradlew installDebugGoogle Play's installer refuses anything below API 21, but many cheap head units still run Android 4.4. The project therefore ships two flavours of the same app:
| Flavour | minSdk | Where it goes |
|---|---|---|
legacy |
19 | The sideloadable APK on GitHub Releases — works on KitKat |
play |
21 | The App Bundle uploaded to the Play Store |
./gradlew assembleLegacyRelease # APK for sideloading
./gradlew bundlePlayRelease # AAB for the Play ConsoleBoth share the same applicationId, so any given device only ever sees one of
them as "the app".
Release builds are minified with R8 and must be signed. Create a key once — choose your own passwords when prompted:
keytool -genkey -v -keystore release.jks -alias release -keyalg RSA -keysize 2048 -validity 10000Copy keystore.properties.example to keystore.properties and fill in your
values, then:
./gradlew assembleReleasekeystore.properties and *.jks are gitignored — never commit them. Losing
the key means you can't publish updates that upgrade an existing install, so back
it up somewhere safe.
Tagging a version builds and publishes a signed APK automatically:
git tag v0.1.4 && git push origin v0.1.4This needs four repository secrets under Settings → Secrets and variables →
Actions: KEYSTORE_BASE64 (base64 -i release.jks), KEYSTORE_PASSWORD,
KEY_ALIAS and KEY_PASSWORD.
After installing, press the unit's Home button and choose this launcher, then select "Always". To reset the default while developing:
adb shell cmd package set-home-activity com.dashline.launcher/.HomeActivityAll optional — the launcher degrades gracefully without them.
| Permission | Used for | Without it |
|---|---|---|
| Location | Local weather | Weather panel hides, clock still works |
| Notification access | Reading now-playing media | Media widget becomes a launch button |
| Query all packages | Listing installed apps | Required for the app drawer |
Notification access can't be granted by a normal permission dialog — Android requires the user to enable it in system settings. Setup links straight there, and you can revisit it at Settings → Media info access.
Weather comes from Open-Meteo, which is free and needs
no API key or account. Location is read through the platform
LocationManager, so no Play Services dependency. It refreshes every 15 minutes,
and you can switch between °C and °F in Settings.
app/src/main/
├── AndroidManifest.xml # HOME intent-filter, notification listener
├── java/com/dashline/launcher/
│ ├── App.kt # applies saved language + theme at startup
│ ├── BaseActivity.kt # locale, fullscreen, gradient, icon tint, nav
│ ├── HomeActivity.kt # the dashboard
│ ├── CustomizeActivity.kt # live layout editor
│ ├── WidgetHost.kt # binds and renders app widgets
│ ├── SwipeLinearLayout.kt # page-turning container for the drawer
│ ├── AnalogClockView.kt # the analog face
│ ├── AppDrawerActivity.kt # app grid: search, frequent, hide
│ ├── AppPickerActivity.kt # "choose an app for this role"
│ ├── AppAdapter.kt # app grid cells
│ ├── SetupActivity.kt # first-run onboarding
│ ├── SettingsActivity.kt # settings
│ ├── TabAction.kt # the six tabs and what they launch
│ ├── TabOrderActivity.kt # reorder / hide tabs
│ ├── GradientPickerActivity.kt # colour scheme picker
│ ├── GradientThemes.kt # the 7 colour schemes
│ ├── ThemeManager.kt # light / dark / auto
│ ├── LocaleManager.kt # in-app language override
│ ├── MediaMonitor.kt # reads the active MediaSession
│ ├── WeatherRepository.kt # Open-Meteo client
│ ├── AppRepository.kt # query + launch installed apps
│ ├── DefaultLauncher.kt # "make this the home app" helper
│ ├── Prefs.kt # all persisted settings
│ ├── Permissions.kt # runtime permission helpers
│ └── Usage.kt # launch-count tracking
└── res/
├── layout/ # landscape dashboard and all other screens
├── layout-port/ # portrait dashboard (same ids as landscape)
├── values/ # strings, light palette, styles
├── values-night/ # dark palette
├── values-h600dp/ # roomier sizes on taller screens
├── values-v21/ # API 21+ theme attributes
└── values-{ar,de,es,fr,it,pt,ru,tr,zh}/ # translations
Supporting old head units shapes a few decisions worth knowing before you change things:
- Dependencies are pinned to the last KitKat-compatible releases
(appcompat 1.4.2, core-ktx 1.9.0, recyclerview 1.2.1). Bumping to appcompat
1.6+ or core-ktx 1.10+ raises
minSdkto 21 and breaks the build. - Launcher icons ship as PNG mipmaps, because vector and adaptive icons don't
render as app icons before Android 5.0. Adaptive icons in
mipmap-anydpi-v26are used only on API 26+. - API 21+ theme attributes live in
values-v21/so they don't affect KitKat. - Fullscreen goes through
WindowInsetsControllerCompatrather than the rawsystemUiVisibilityflags: from targetSdk 35 Android enforces edge-to-edge and those flags stop behaving predictably. The compat layer maps to them on old devices, so KitKat still works. - The language override wraps each activity's context instead of using
AppCompatDelegate.setApplicationLocales, which needs appcompat 1.6+. - The media panel requires Android 5.0+ (
MediaSessionManager). On KitKat it falls back to acting as a launch button. - Widgets are bound through
ACTION_APPWIDGET_BIND, not the system's widget picker: that picker binds on the caller's behalf, which needs the signature-levelBIND_APPWIDGETpermission no normal app can hold.
Screenshots in this README are captured from a real unit. To refresh them after a UI change, connect the head unit (or an emulator) with USB debugging on and run:
./tools/capture-screenshots.shRead the Compatibility notes above before upgrading any dependency — several are pinned deliberately to keep Android 4.4 support.
- Reorderable favourites dock (drag and drop)
- Hourly forecast in the weather panel
- Quick-dial contacts on the phone card
GNU General Public License v3.0 only — see LICENSE. There is no "or any later version" clause, so v3 is the licence, not a floor.
Copyright © 2026 Metehan Kaygısız.
You may use, study, share and modify Dashline. If you distribute a modified version, it has to stay under the GPL and ship its source, so the people running it keep the same freedoms.
Source files carry SPDX-License-Identifier: GPL-3.0-only, so the terms travel
with the code rather than only with the repository.