build(android): Cargo configuration, crate-type cdylib and android_main entrypoint #42

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2026-10-25T13:49:39+01:00

harald commented

2026-10-25 13:49:39 +01:00

Description

To enable building ink-notes for Android, the workspace must be configured to produce a dynamic C library (cdylib) alongside the desktop binary, and provide an entrypoint that binds winit to Android's activity lifecycle.

Scope of Work

Update Cargo.toml:
- Add crate-type = ["cdylib", "rlib"] under [lib].
- Add conditional target dependencies for cfg(target_os = "android"): android-activity, winit (with matching Android feature flags to current eframe), and android_logger.
- Configure [package.metadata.android] with package identifier eu.pansi.inknotes, min SDK 26, target SDK 34.
Abstract application entrypoint:
- Ensure the core application initialization logic lives in lib.rs.
- Keep src/main.rs guarded with #[cfg(not(target_os = "android"))] for desktop execution.
- Implement #[no_mangle] fn android_main(app: AndroidApp) in src/lib.rs (guarded with #[cfg(target_os = "android")]).
- Configure eframe::NativeOptions with options.event_loop_builder passing builder.with_android_app(app).
- Initialize android_logger at start of android_main.

Acceptance Criteria

cargo check --target aarch64-linux-android succeeds without compiler errors.
Desktop builds (cargo build) continue to compile and run unaffected.

### Description To enable building `ink-notes` for Android, the workspace must be configured to produce a dynamic C library (`cdylib`) alongside the desktop binary, and provide an entrypoint that binds `winit` to Android's activity lifecycle. ### Scope of Work 1. Update `Cargo.toml`: - Add `crate-type = ["cdylib", "rlib"]` under `[lib]`. - Add conditional target dependencies for `cfg(target_os = "android")`: `android-activity`, `winit` (with matching Android feature flags to current `eframe`), and `android_logger`. - Configure `[package.metadata.android]` with package identifier `eu.pansi.inknotes`, min SDK 26, target SDK 34. 2. Abstract application entrypoint: - Ensure the core application initialization logic lives in `lib.rs`. - Keep `src/main.rs` guarded with `#[cfg(not(target_os = "android"))]` for desktop execution. - Implement `#[no_mangle] fn android_main(app: AndroidApp)` in `src/lib.rs` (guarded with `#[cfg(target_os = "android")]`). - Configure `eframe::NativeOptions` with `options.event_loop_builder` passing `builder.with_android_app(app)`. - Initialize `android_logger` at start of `android_main`. ### Acceptance Criteria - `cargo check --target aarch64-linux-android` succeeds without compiler errors. - Desktop builds (`cargo build`) continue to compile and run unaffected.

harald commented

2026-10-25 13:54:32 +01:00

Corrections after checking the code (planned for the future, not started)

ink-notes does not use eframe. It drives winit 0.29 (vendored and patched in vendor/winit), egui-winit 0.27 and wgpu 0.19 directly, so there is no eframe::NativeOptions. On Android:
- enable the winit feature android-native-activity;
- build the event loop with EventLoopBuilder::new().with_android_app(app) (winit::platform::android::EventLoopBuilderExtAndroid).
- The Wayland patch in vendor/winit does not affect Android.
There is no InkNotesApp struct. The whole app is one event loop in src/main.rs (~4300 lines, fn main plus helpers). src/lib.rs only exports the modules. The first and largest step is to move the event loop into the library, e.g. ink_notes::run(event_loop, options), so that both main() and android_main() call it. The desktop behaviour must not change.
Several dependencies are Linux/desktop only and have to be gated with cfg(not(target_os = "android")) or replaced:
- octotablet (pen input, see #44)
- wayland-client, wayland-backend and wayland-protocols (on-screen keyboard, src/osk.rs)
- arboard (clipboard)
- webbrowser
- the self-updater (src/updater.rs)
- the built-in file picker that reads XDG user dirs (src/file_picker.rs)
- fs2 file locks (probably fine, to be checked)
wgpu on Android must create the surface only after Resumed, and drop it on Suspended. Currently the window and surface are created once at startup.
android_logger is optional. The app logs with eprintln!, which goes nowhere on Android, so logging would need to switch to log.

Revised acceptance criteria stay the same:

cargo check --target aarch64-linux-android passes.
The desktop build and its tests are unchanged.

**Corrections after checking the code** (planned for the future, not started) - ink-notes does not use **eframe**. It drives winit 0.29 (vendored and patched in `vendor/winit`), egui-winit 0.27 and wgpu 0.19 directly, so there is no `eframe::NativeOptions`. On Android: - enable the winit feature `android-native-activity`; - build the event loop with `EventLoopBuilder::new().with_android_app(app)` (`winit::platform::android::EventLoopBuilderExtAndroid`). - The Wayland patch in `vendor/winit` does not affect Android. - There is no `InkNotesApp` struct. The whole app is one event loop in `src/main.rs` (~4300 lines, `fn main` plus helpers). `src/lib.rs` only exports the modules. The first and largest step is to move the event loop into the library, e.g. `ink_notes::run(event_loop, options)`, so that both `main()` and `android_main()` call it. The desktop behaviour must not change. - Several dependencies are Linux/desktop only and have to be gated with `cfg(not(target_os = "android"))` or replaced: - `octotablet` (pen input, see #44) - `wayland-client`, `wayland-backend` and `wayland-protocols` (on-screen keyboard, `src/osk.rs`) - `arboard` (clipboard) - `webbrowser` - the self-updater (`src/updater.rs`) - the built-in file picker that reads XDG user dirs (`src/file_picker.rs`) - `fs2` file locks (probably fine, to be checked) - wgpu on Android must create the surface only after `Resumed`, and drop it on `Suspended`. Currently the window and surface are created once at startup. - `android_logger` is optional. The app logs with `eprintln!`, which goes nowhere on Android, so logging would need to switch to `log`. Revised acceptance criteria stay the same: - `cargo check --target aarch64-linux-android` passes. - The desktop build and its tests are unchanged.

harald referenced this issue from a commit

2026-10-26 14:10:29 +01:00

refactor: move the event loop into the library as app::run (prep for Issue #42)

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Reference: harald/ink-notes#42