Add C-ABI iOS/Swift FFI wrapper crate (dithering only)#56
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Adds `packages/rust/ios`, a thin C-ABI wrapper around `epaper-dithering-core` so the OpenDisplay iOS app can call the same OKLab dithering as the website/Python instead of its divergent sRGB-Euclidean Swift reimplementation. Scope is deliberately minimal — matching + error diffusion only. Tone/ gamut/exposure/saturation pre-processing is NOT surfaced: the app keeps its own tone-compression pass in Swift for now and hands us already-pre-processed pixels, so we run at DitherConfig defaults. Design (locked for iOS-only): - Plain C ABI (`ed_dither`, `ed_abi_version`), no UniFFI. - Caller-allocated output: output length is deterministically width*height, so Swift allocates; nothing crosses the boundary to free. - Indices returned in the caller's palette order, so the app's existing wire-format packing needs no remap. - Panics can't cross FFI (catch_unwind -> ED_ERR_PANIC); errors are negative status codes. Wiring: - staticlib+cdylib+rlib crate, excluded from the workspace (like `wasm`) so Linux `cargo build --workspace` and the Python sdist vendoring are unaffected. - build-xcframework.sh produces EpaperDithering.xcframework (device arm64 + simulator arm64/x86_64) — the only Xcode-gated step. - ios-test.yml runs the FFI unit/integration tests on the HOST target (Ubuntu, no Xcode) on every PR; includes a test asserting byte-for-byte parity with calling core::dither directly. Not built/verified locally: no Rust toolchain on the authoring machine. CI (ios-test.yml) builds and tests the FFI; the XCFramework must be built on a Mac with Rust + iOS targets. App-side ImageProcessor integration is a follow-up PR in the app repo. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KCmHoU5FHgL4Sec6EFfLpy
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Retargeting to davelee98/epaper-dithering (origin) as intended. |
Codecov Report✅ All modified and coverable lines are covered by tests. 📢 Thoughts on this report? Let us know! |
Matches the idiom already used in the wasm crate. Verified locally: cargo test (6 pass, incl. core::dither byte-parity), cargo clippy clean, and build-xcframework.sh produces a valid XCFramework (device arm64 + simulator arm64/x86_64) exporting ed_dither / ed_abi_version. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KCmHoU5FHgL4Sec6EFfLpy
The XCFramework is vendored into the app repo's git, so keep the static archives lean: release profile now uses lto + codegen-units=1 + strip="debuginfo", and build-xcframework.sh runs `strip -S -x` on each archive (retaining the ed_dither/ed_abi_version globals needed for linking). Cuts the framework from ~54MB to ~36MB. panic stays "unwind" — the FFI relies on catch_unwind. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KCmHoU5FHgL4Sec6EFfLpy
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This is so I can re-use the Rust core in the iOS app. |
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Adds
packages/rust/ios— a thin C-ABI wrapper aroundepaper-dithering-coreso the OpenDisplay iOS app can call the same OKLab dithering as the website / Python, replacing a divergent sRGB-Euclidean Swift reimplementation. Sibling of the existingwasmcrate.Scope (deliberately minimal)
Matching + error diffusion only. Tone / gamut / exposure / saturation pre-processing is not surfaced — the app keeps its tone pass in Swift and hands us pre-processed pixels, so we run at
DitherConfigdefaults.API (
include/epaper_dithering.h)ed_dither(...) -> int32_t— dither flat sRGB → palette indices.ed_abi_version() -> uint32_t.Design: plain C ABI (no UniFFI); caller-allocated output (length is deterministically
width*height, so nothing crosses the boundary to free); indices in the caller's palette order (lines up with the app's wire packing, no remap); panics can't cross FFI (catch_unwind→ status code).Wiring
staticlib+cdylib+rlibcrate, excluded from the workspace (likewasm) so Linuxcargo build --workspaceand the Python sdist vendoring (Packaging issues with pypi package #40) are unaffected.build-xcframework.sh→ device arm64 + simulator arm64/x86_64 XCFramework, stripped/LTO'd (~36 MB). The only Xcode-gated step..github/workflows/ios-test.yml— builds & tests the FFI on the host target (Ubuntu, no Xcode) every PR, including a byte-for-byte parity test againstcore::dither.Verified locally (Rust 1.97.1, Xcode 26.6)
cargo test→ 6/6;cargo clippy -- -D warnings→ clean;build-xcframework.sh→ valid XCFramework exportinged_dither/ed_abi_version. Already consumed by the OpenDisplay iOS app (vendored XCFramework), where its output matches the reference byte-for-byte on real photos.🤖 Generated with Claude Code