Module build_android 

cargo xtask build-android: build the examples’ shared libraries, then the APK that packages them.

Two tools, split along the language boundary. cargo ndk cross-compiles the *_android crates, which hold the exported entry points and nothing else, and drops each .so into the app’s jniLibs directory, which is where Gradle looks for native libraries and packages whatever it finds; Gradle then compiles the activities and assembles the APK around them. The libraries are built first because an APK without them is an activity that cannot start.

Both tools configure themselves from the environment: cargo ndk reads the NDK out of ANDROID_NDK_HOME (or the newest one under ANDROID_HOME/ndk) and Gradle reads the SDK out of ANDROID_HOME (or android/local.properties).

Re-exports

use std::path::Path; 🔒

use std::process::Command; 🔒

use super::BuildAndroidArgs; 🔒

use super::step; 🔒

Constants

ABI 🔒

The ABI the APK carries. Kept in step with abiFilters in android/app/build.gradle.kts, which is what decides what the APK accepts.

ANDROID_DIR 🔒

The Android application’s Gradle project, relative to the workspace root.

JNI_LIBS_DIR 🔒

Where the Rust build puts the shared library, relative to the workspace root. This is Gradle’s own jniLibs source directory, whose subdirectory names are ABI identifiers, so cargo ndk -o writes exactly its layout.

LIBRARY_CRATES 🔒

The crates that build the libraries the activities load, in the order the tab bar lists them. Each is a cdylib exporting android_main, and each activity names the one it loads in its android.app.lib_name manifest entry — the package is the example’s name with _android appended, while the library keeps the example’s own name.

PLATFORM 🔒

The API level the library is compiled and linked against. Kept in step with minSdk in android/app/build.gradle.kts: linking against a higher one would let the library call into API the APK’s own floor does not promise.

Functions

apk 🔒

Assemble the APK, which packages whatever library staged.

apk_path 🔒

The APK the selected build type produces.

library 🔒

Cross-compile the libraries and stage them for the APK.

run

Build the shared library and the APK that packages it.