android-compose

RPort Android Compose Sample

Minimal Jetpack Compose sample for the real UniFFI embedding API. The app keeps two independent RSession instances alive, evaluates code, renders PNG plots, lists and loads a bundled pure-R package, and cancels a long-running eval.

Use this example to learn how to embed R in your own Android app. For a complete editor, console, project browser and plot history, use the R Workbench. These are independent Gradle projects; the example uses the Rust/UniFFI API directly, without workbench code.

What It Demonstrates

• Two Android tabs backed by separate Rust R sessions.
• App-private runtime paths via configureAndroidPaths(...).
• Typed asynchronous eval results through evalAsync(...) and takeResult(...).
• PNG plot rendering through renderAsync(...) and takeResult(...).
• Pure-R package discovery/loading through installedPackages() and loadPackage(...).
• S3 dispatch from the bundled androiddemo package.
• Cooperative cancellation via operation-specific cancelOperation(...).

Callbacks carry the operation ID returned by evalAsync or renderAsync. The sample accepts progress only for the active ID and polls terminal results by ID, so delayed callbacks cannot overwrite a newer operation. Console output comes from the completed result, including fast operations that finish before their ID reaches the caller. UI state transitions run on the main dispatcher; blocking runtime calls run on the IO dispatcher.

Prepare Bindings

Generate Kotlin bindings and build the Android native library from the repo root:

scripts/generate_uniffi_bindings.sh --out-dir examples/android-compose/app/generated
cargo ndk -t arm64-v8a -o examples/android-compose/app/src/main/jniLibs build -p r-uniffi --release

The checked-in crates/r-uniffi/uniffi.toml sets the Kotlin package to com.rport.uniffi, which matches the sample imports.

For a versioned local release layout instead of editing the sample tree directly, run:

scripts/package_release_artifacts.sh --check

The generated bundle contains Kotlin bindings under bindings/kotlin/ and the Android shared library at android/jniLibs/arm64-v8a/libr_uniffi.so.

Build And Run

From the repository root, after preparing bindings and the native library:

examples/android-compose/gradlew -p examples/android-compose :app:assembleDebug
adb install -r examples/android-compose/app/build/outputs/apk/debug/app-debug.apk
adb shell am start -W -n com.rport.sample/.MainActivity

The example has its own checksum-pinned Gradle wrapper. Use JDK 17 and an Android SDK with API 35 installed. You can also open this directory directly in Android Studio.

Use the Showcase action first. It loads androiddemo, runs an S3 method in Session A, proves Session B has separate state, and renders labeled line/point plots.

Reproducible Showcase Artifacts

The host-side artifact script exercises the same runtime capabilities without an emulator and writes a transcript plus plot PNGs:

scripts/android_showcase_artifacts.sh --check

Generated files:

• target/android-showcase/showcase-transcript.txt
• target/android-showcase/line-plot.png
• target/android-showcase/point-plot.png

Demo Plot Scripts

plot(c(1, 2, 3, 4), c(1, 4, 9, 16), type = "l", col = "blue", lwd = 2,
     main = "Android growth", xlab = "x", ylab = "x^2")
plot(c(1, 2, 3, 4), c(3, 1, 4, 2), type = "b", col = "green", cex = 1.3,
     main = "Android points", xlab = "sample", ylab = "value")