refactor(mobile): move the native core decoders into a codecs crate (#32765)

* refactor(mobile): move the native core decoders into a codecs crate

* make Format private

* rename the decode export and options for what they hold

* drop the unused ios and server groups and rename the target params

(cherry picked from commit 11bf875313782b8a9e10269bb6f85226b7bdcd72)

native/Cargo.lock

@@ -56,6 +56,18 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
+[[package]]
+name = "codecs"
+version = "0.1.0"
+dependencies = [
+ "jxl",
+ "libc",
+ "moxcms",
+ "pic-scale",
+ "quick_cache",
+ "rayon",
+]
+
 [[package]]
 name = "combine"
 version = "4.6.8"
@@ -287,12 +299,7 @@ dependencies = [
 name = "native_core"
 version = "0.1.0"
 dependencies = [
- "jxl",
- "libc",
- "moxcms",
- "pic-scale",
- "quick_cache",
- "rayon",
+ "codecs",
 ]
 
 [[package]]

native/Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
-members = ["crates/native_core", "crates/native_core_ffi"]
+members = ["crates/codecs", "crates/native_core", "crates/native_core_ffi"]
 
 [workspace.package]
 version = "0.1.0"

native/README.md

@@ -5,8 +5,9 @@ Rust code that ships inside the mobile app. Flutter compiles it from source thro
 in `mobile/` sets one up, otherwise install [rustup](https://rustup.rs) once and the build
 fetches the pinned toolchain itself.
 
-- `crates/native_core`: the shared logic
-- `crates/native_core_ffi`: the C ABI, cbindgen writes `include/native_core.h`
+- `crates/codecs`: the image decoders, a feature each, behind one `decode`
+- `crates/native_core`: the shared logic, a feature per part and a group per target
+- `crates/native_core_ffi`: the C ABI on the `flutter` group, cbindgen writes `include/native_core.h`
 - `native_core`: Flutter package with the build hook and the ffigen bindings
   (`NOTICES` carries the licenses of the crates compiled into the core, update it with the dependencies)
 

native/crates/codecs/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "codecs"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[features]
+default = ["jxl"]
+jxl = ["dep:jxl", "dep:rayon"]
+
+[dependencies]
+jxl = { workspace = true, optional = true }
+libc = { workspace = true }
+moxcms = { workspace = true }
+pic-scale = { workspace = true }
+quick_cache = { workspace = true }
+rayon = { workspace = true, optional = true }
+
+[lints]
+workspace = true

native/crates/codecs/src/jxl.rs

@@ -70,7 +70,7 @@ impl JxlParallelRunner for Cancellable<'_> {
 }
 
 impl<'a> Jxl<'a> {
-    pub fn open(mut input: &'a [u8], target: Target) -> Option<Self> {
+    pub fn open(mut input: &'a [u8], color_space: Target) -> Option<Self> {
         let mut options = JxlDecoderOptions::default();
         // Colour transforms need straight alpha; premultiplying happens last.
         options.alpha_mode = AlphaMode::Unpremultiplied;
@@ -85,7 +85,7 @@ impl<'a> Jxl<'a> {
             .ok()?;
         let profile = decoder.output_color_profile()?;
         if let Some(cicp) = cicp(profile)
-            && (target == Target::Source || color::is_srgb(cicp))
+            && (color_space == Target::Source || color::is_srgb(cicp))
         {
             if color::is_hdr(cicp) {
                 decoder
@@ -121,11 +121,11 @@ impl<'a> Jxl<'a> {
         })
     }
 
-    /// Decodes the first frame unless cancelled, downscaled to cover `target` pixels and to fit
-    /// within `max_pixel_size`.
+    /// Decodes the first frame unless cancelled, downscaled to cover `target_size` pixels and to
+    /// fit within `max_pixel_size`.
     pub fn decode(
         mut self,
-        target: Option<(usize, usize)>,
+        target_size: Option<(usize, usize)>,
         max_pixel_size: usize,
         cancelled: &AtomicBool,
     ) -> Option<Image> {
@@ -139,7 +139,7 @@ impl<'a> Jxl<'a> {
         let pixel_bytes =
             format.color_type.samples_per_pixel() * format.color_data_format?.bytes_per_sample();
         let stride = w.checked_mul(pixel_bytes)?;
-        let size = resize::cover((w, h), target, max_pixel_size);
+        let size = resize::cover((w, h), target_size, max_pixel_size);
         let samples = if color::is_hdr(self.cicp) {
             let mut rgba = Pixels::zeroed(w, h, pixel_bytes)?;
             self.decode_frame(&mut rgba, stride, cancelled)?;

native/crates/codecs/src/lib.rs

@@ -0,0 +1,49 @@
+use std::sync::atomic::AtomicBool;
+
+use color::Target;
+use image::Image;
+
+pub mod color;
+pub mod image;
+#[cfg(feature = "jxl")]
+pub mod jxl;
+mod resize;
+
+enum Format {
+    #[cfg(feature = "jxl")]
+    Jxl,
+}
+
+pub struct Options {
+    pub color_space: Target,
+
+    /// Downscales to the smallest size that still fills this.
+    pub target_size: Option<(usize, usize)>,
+
+    /// Downscales to fit within this many pixels per side.
+    pub max_pixel_size: usize,
+}
+
+fn probe(data: &[u8]) -> Option<Format> {
+    #[cfg(feature = "jxl")]
+    if matches!(
+        ::jxl::api::check_signature(data),
+        ::jxl::api::JxlSignature::Codestream | ::jxl::api::JxlSignature::Container
+    ) {
+        return Some(Format::Jxl);
+    }
+
+    None
+}
+
+/// Decodes the first frame of `data` unless cancelled.
+pub fn decode(data: &[u8], options: &Options, cancelled: &AtomicBool) -> Option<Image> {
+    match probe(data)? {
+        #[cfg(feature = "jxl")]
+        Format::Jxl => jxl::Jxl::open(data, options.color_space)?.decode(
+            options.target_size,
+            options.max_pixel_size,
+            cancelled,
+        ),
+    }
+}

native/crates/codecs/src/resize.rs

@@ -47,16 +47,16 @@ impl Lanczos for u16 {
     }
 }
 
-/// The size of `size` scaled down to cover `target` and to fit within `max_pixel_size`, if that
-/// is smaller.
+/// The size of `size` scaled down to cover `target_size` and to fit within `max_pixel_size`, if
+/// that is smaller.
 pub(crate) fn cover(
     (w, h): (usize, usize),
-    target: Option<(usize, usize)>,
+    target_size: Option<(usize, usize)>,
     max_pixel_size: usize,
 ) -> Option<(usize, usize)> {
     // Scales as side ratios, so the side that sets the scale lands exactly on its limit.
     let fit = (max_pixel_size, w.max(h));
-    let (num, den) = match target {
+    let (num, den) = match target_size {
         Some((tw, th)) => {
             let cover = if tw * h >= th * w { (tw, w) } else { (th, h) };
             if cover.0 * fit.1 < fit.0 * cover.1 {

native/crates/codecs/tests/jxl.rs

@@ -1,11 +1,19 @@
+#![cfg(feature = "jxl")]
+
 use std::sync::atomic::AtomicBool;
 
-use native_core::color::{CicpColorPrimaries, CicpProfile, Target, TransferCharacteristics};
-use native_core::image::{Image, Pixels, Samples};
-use native_core::jxl::Jxl;
+use codecs::Options;
+use codecs::color::{CicpColorPrimaries, CicpProfile, Target, TransferCharacteristics};
+use codecs::image::{Image, Pixels, Samples};
+use codecs::jxl::Jxl;
 
-fn decode(data: &[u8], target: Target) -> Option<Image> {
-    Jxl::open(data, target)?.decode(None, 16384, &AtomicBool::new(false))
+fn decode(data: &[u8], color_space: Target) -> Option<Image> {
+    let options = Options {
+        color_space,
+        target_size: None,
+        max_pixel_size: 16384,
+    };
+    codecs::decode(data, &options, &AtomicBool::new(false))
 }
 
 fn decode_srgb(data: &[u8]) -> Option<Pixels<u8>> {

native/crates/native_core/Cargo.toml

@@ -4,13 +4,16 @@ version.workspace = true
 edition.workspace = true
 license.workspace = true
 
+[features]
+convert = []
+rotate = []
+thumbhash = []
+jxl = ["codecs/jxl"]
+# One group per target.
+flutter = ["convert", "rotate", "thumbhash", "jxl"]
+
 [dependencies]
-jxl = { workspace = true }
-libc = { workspace = true }
-moxcms = { workspace = true }
-pic-scale = { workspace = true }
-quick_cache = { workspace = true }
-rayon = { workspace = true }
+codecs = { path = "../codecs", default-features = false, optional = true }
 
 [lints]
 workspace = true

native/crates/native_core/src/lib.rs

@@ -1,9 +1,10 @@
-pub mod color;
+#[cfg(feature = "codecs")]
+pub use codecs;
+#[cfg(feature = "convert")]
 pub mod convert;
-pub mod image;
-pub mod jxl;
-mod resize;
+#[cfg(feature = "rotate")]
 pub mod rotate;
+#[cfg(feature = "thumbhash")]
 pub mod thumbhash;
 
 pub fn version() -> &'static str {

native/crates/native_core/tests/convert.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "convert")]
+
 use native_core::convert::convert_1010102;
 
 #[test]

native/crates/native_core/tests/rotate.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "rotate")]
+
 use native_core::rotate::{Orientation, rotate};
 
 #[test]

native/crates/native_core/tests/thumbhash.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "thumbhash")]
+
 use native_core::thumbhash::decode;
 
 // Expected pixels come from the old Swift decoder patched to round like the Java did (it truncated),

native/crates/native_core_ffi/Cargo.toml

@@ -10,7 +10,7 @@ name = "native_core_ffi"
 crate-type = ["cdylib", "staticlib"]
 
 [dependencies]
-native_core = { path = "../native_core" }
+native_core = { path = "../native_core", features = ["flutter"] }
 libc = { workspace = true }
 
 [target.'cfg(target_os = "android")'.dependencies]

native/crates/native_core_ffi/build.rs

@@ -3,7 +3,7 @@ use std::path::Path;
 fn main() {
     // Files that define exported items. A directory here would make Flutter rerun the hook every build.
     println!("cargo:rerun-if-changed=src/lib.rs");
-    println!("cargo:rerun-if-changed=src/jxl.rs");
+    println!("cargo:rerun-if-changed=src/decode.rs");
     println!("cargo:rerun-if-changed=src/thumbhash.rs");
     println!("cargo:rerun-if-changed=cbindgen.toml");
     let crate_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();

native/crates/native_core_ffi/src/decode.rs

@@ -10,9 +10,9 @@ use jni::{
     objects::{JByteBuffer, JClass, JIntArray},
     sys::{jint, jlong},
 };
-use native_core::color::Target;
-use native_core::image::{Image, Samples};
-use native_core::jxl::Jxl;
+use native_core::codecs::color::Target;
+use native_core::codecs::image::{Image, Samples};
+use native_core::codecs::{self, Options};
 
 use super::guard;
 
@@ -30,7 +30,7 @@ pub struct NativeCoreImageInfo {
     pub transfer: u8,
 }
 
-/// Decodes a JPEG XL image to premultiplied RGBA in sRGB, or with `keep_space`, in the image's own
+/// Decodes an image to premultiplied RGBA in sRGB, or with `keep_space`, in the image's own
 /// space when it has BT.709, BT.2020 or Display P3 primaries with the sRGB, PQ or HLG transfer.
 /// Unless either is 0, it is downscaled to cover `target_width` x `target_height`, and it never
 /// exceeds `max_pixel_size` pixels per side. `info` gets the size and space. The caller frees the
@@ -42,7 +42,7 @@ pub struct NativeCoreImageInfo {
 /// `cancelled` must be null or valid for the call and only changed through `native_core_cancel`.
 /// `info` must be null or a valid writable pointer, outside `data`.
 #[unsafe(no_mangle)]
-pub unsafe extern "C" fn native_core_jxl_decode(
+pub unsafe extern "C" fn native_core_decode_image(
     data: *const u8,
     len: size_t,
     keep_space: bool,
@@ -60,16 +60,19 @@ pub unsafe extern "C" fn native_core_jxl_decode(
         let cancelled = unsafe { AtomicBool::from_ptr(cancelled) };
         // SAFETY: the caller provides a buffer readable for len bytes.
         let input = unsafe { slice::from_raw_parts(data, len) };
-        let target = if keep_space {
+        let color_space = if keep_space {
             Target::Source
         } else {
             Target::Srgb
         };
-        let cover = (target_width > 0 && target_height > 0)
+        let target_size = (target_width > 0 && target_height > 0)
             .then_some((target_width as usize, target_height as usize));
-        let Some(Image { cicp, samples }) = Jxl::open(input, target)
-            .and_then(|image| image.decode(cover, max_pixel_size as usize, cancelled))
-        else {
+        let options = Options {
+            color_space,
+            target_size,
+            max_pixel_size: max_pixel_size as usize,
+        };
+        let Some(Image { cicp, samples }) = codecs::decode(input, &options, cancelled) else {
             return ptr::null_mut();
         };
         let (width, height, bit_depth, pixels) = match samples {
@@ -93,7 +96,7 @@ pub unsafe extern "C" fn native_core_jxl_decode(
 /// Asks the decode given `flag` to stop early.
 ///
 /// # Safety
-/// `flag` must be null or valid and otherwise only read by `native_core_jxl_decode`.
+/// `flag` must be null or valid and otherwise only read by `native_core_decode_image`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn native_core_cancel(flag: *mut bool) {
     if !flag.is_null() {
@@ -104,7 +107,7 @@ pub unsafe extern "C" fn native_core_cancel(flag: *mut bool) {
 
 #[cfg(target_os = "android")]
 #[unsafe(no_mangle)]
-pub extern "system" fn Java_app_alextran_immich_NativeImage_decodeJxl<'caller>(
+pub extern "system" fn Java_app_alextran_immich_NativeImage_decode<'caller>(
     mut env: EnvUnowned<'caller>,
     _class: JClass<'caller>,
     data: jlong,
@@ -121,7 +124,7 @@ pub extern "system" fn Java_app_alextran_immich_NativeImage_decodeJxl<'caller>(
         // SAFETY: Kotlin passes a live native buffer of `length` bytes and a direct buffer it only
         // changes through `cancel`, and the output is valid.
         let rgba = unsafe {
-            native_core_jxl_decode(
+            native_core_decode_image(
                 data as *const u8,
                 length as size_t,
                 false,
@@ -154,7 +157,7 @@ pub extern "system" fn Java_app_alextran_immich_NativeImage_cancel<'caller>(
 ) {
     env.with_env(|env| -> jni::errors::Result<()> {
         let flag = env.get_direct_buffer_address(&flag)?.cast::<bool>();
-        // SAFETY: the buffer is the live one-byte flag Kotlin passed to `decodeJxl`.
+        // SAFETY: the buffer is the live one-byte flag Kotlin passed to `decode`.
         unsafe { native_core_cancel(flag) };
         Ok(())
     })

native/crates/native_core_ffi/src/lib.rs

@@ -9,7 +9,7 @@ mod android;
 mod bitmap;
 #[cfg(target_os = "android")]
 mod convert;
-mod jxl;
+mod decode;
 #[cfg(target_os = "android")]
 mod rotate;
 mod thumbhash;

native/native_core/hook/build.dart

@@ -11,6 +11,7 @@ const _manifests = [
   '../.cargo/config.toml',
   '../Cargo.toml',
   '../Cargo.lock',
+  '../crates/codecs/Cargo.toml',
   '../crates/native_core/Cargo.toml',
   '$_crate/Cargo.toml',
   '$_crate/rust-toolchain.toml',