2.5 KiB
Gearslip
Bring any app to your car screen.
What Gearslip is
Gearslip is an Android Auto client for the phone. It speaks the Android Auto protocol directly to a car head unit over USB, with no Google software in the path. Gearslip acts as a Car App Library host: an app that ships a car interface hands Gearslip a template, and Gearslip renders that template natively on the car screen. Nothing is mirrored from the phone. For apps without a car interface, Gearslip offers a separate screen-sharing mode.
The author reverse-engineered the protocol for interoperability, so that a client other than Google's own can talk to a car head unit.
Status
- Templated apps work. Gearslip renders all 16 template types that the Car App Library defines, and it draws its own keyboard for search and sign-in. It has been tested against several real navigation and media apps.
- Media playback works. Gearslip lets you browse and control car-enabled media apps from the car screen, with lyrics and playback state, over the same host connection.
- A real head unit needs a certificate that Google controls. A head unit accepts only a phone identity that chains to Google's Automotive Link certificate authority, and Google alone issues those certificates. Gearslip does not ship one. Without it, Gearslip runs and renders correctly against a debug harness, but a real car rejects the connection. A leaked certificate exists that older head units accept; newer firmware and Google's reference tooling reject it.
- Gearslip needs no adb, root, or Shizuku. Every feature relies on an ordinary Android permission or an on-device consent dialog.
Building
./gradlew :gearslip:assembleDebug
The APK lands at build/Gearslip-debug.apk.
A release build needs a signing key. Copy keystore.properties.example to
keystore.properties, fill in your own values, and run
./gradlew :gearslip:assembleRelease. Git ignores both the properties file and the
keystore. Without them, the debug build still works.
Writing apps for Gearslip
docs/BUILDING_APPS.md specifies how to write apps that Gearslip can render: templated apps, media apps, and the Gearslip app protocol.
License
Gearslip is licensed under AGPL-3.0; see LICENSE. The author offers a separate commercial license for private use outside the AGPL's terms; see NOTICE.md.