Sergio Gonzalez Martin

This commit introduces a **new capability** to explicitly control the EXIF parsing mechanism within Skia. It adds a `ForceSkExif` method, primarily for **Chromium-specific EXIF handling**, which allows consumers to **force the use of the C++ `SkExif::Parse` implementation** even when the `rust_exif` feature is globally enabled. This modification to the **SkExif parsing logic** provides a critical override, ensuring specific downstream requirements can bypass the Rust-based parser when necessary. The change involves adding a new header `SkExifChromium.h` and updating `SkExif.cpp` to conditionally select the parser based on this new global flag.

This commit introduces the **initial implementation** of the **`rust_exif` component**, providing a **new capability** for EXIF parsing written in Rust. This **core Rust logic** (`exif_parse.rs`) handles TIFF/EXIF data, including specific tags like Apple MakerNote for HDR headroom, and is exposed to C++ via a **Foreign Function Interface (FFI)** (`FFI.rs`, `FFI.cpp`, `FFI.h`). The new `rust_exif` module is integrated into the build system (`BUILD.gn`, `BUILD.bazel`) and includes **comparison tests** (`RustExifTest.cpp`) to ensure its behavior matches the existing `SkExif::Parse` functionality. This work establishes a Rust-based alternative for EXIF processing, ensuring consistent results with current C++ implementations.

This commit introduces a **new capability** for **Chromium's integration with Skia's codec subsystem**, allowing it to **force `skcms` for ICC profile parsing**. A new **`ICCProfileChromium` class** is added in `include/private/chromium/SkCodecsICCProfileChromium.h`, providing methods like `ForceSkcms` and `Make` to explicitly enable `skcms` processing. This ensures that even when Rust-based ICC parsing is enabled, Chromium can override and mandate `skcms` for color profile interpretation, affecting how images are color-managed. This feature also extends `skcms` forcing to non-`skCodec` consumers within Chromium, with necessary build system updates to expose these new components.

This commit performs **maintenance refactoring** within the **`rust/icc` module**, specifically in `FFI.rs`, to resolve nine **Clippy lint errors** that were causing build failures in Chromium's `clippy-driver` pass. The changes include simplifying nested `if-let` chains using `.and_then()` in functions like `parse_icc_profile` and `convert_to_a2b`, removing needless borrowed references, replacing range-based loops with iterator-based enumeration, and optimizing redundant closures. These **code quality improvements** ensure compliance with linting standards and facilitate successful builds without introducing any **functional changes** to the ICC profile parsing or conversion logic.

This commit provides a **bug fix** and **refactoring** for **ICC profile processing** within the `rust/icc` module, resolving two distinct issues that caused CQ failures. It **corrects XYZ synthesis for GRAY profiles** by synthesizing a diagonal matrix from the profile's white point when colorant tags are absent, ensuring proper `to_xyzd50` conversion. Additionally, it **improves TRC (Tone Reproduction Curve) handling** by modifying the `IccProfile` structure to directly pass raw parametric or table bytes for `TRC` data, eliminating `±1 ULP` approximation errors previously seen with `skcms_ApproximateCurve` for profiles like Apple RGB. This change removes the now-obsolete `ApproximateCurveWrapper` and ensures **more accurate and robust color space conversions** for various ICC profiles.

This commit provides a **bug fix** for the **Rust ICC parser's C++ bridge** (`FFI.cpp`), addressing two critical issues that impacted **ICC profile parsing**. It corrects an **endianness problem** in `ApproximateCurveWrapper` by explicitly byte-swapping `uint16_t` entries, ensuring multi-entry TRC curves are correctly approximated on little-endian systems and preventing incorrect color rendering. Additionally, it resolves an issue in `ToSkcmsA2B` and `ToSkcmsB2A` where empty grid data for CLUT-less A2B/B2A tags could lead to spurious errors, by guarding assignments with `!grid_data.empty()`. These changes ensure **accurate color management** and robust profile handling, especially when `skia_use_rust_icc` is enabled.

This commit **fixes a use-after-free bug** in the **Rust ICC profile parsing** path, specifically within the `MakeICCProfileWithRust` function. Previously, `skcms_ICCProfile` objects returned by this function contained dangling pointers to data from a stack-allocated `rust_icc::IccProfile`, leading to potential crashes. The **bug fix** introduces a **new `fRetainedData` member** (a `std::shared_ptr<void>`) to the `ColorProfile` class, which now **heap-allocates** the `rust_icc::IccProfile` and retains ownership of its underlying data buffers. This ensures the necessary data remains valid for the lifetime of the `ColorProfile`, significantly improving the **stability of color profile handling** when using the Rust backend.

This commit delivers a **bug fix** for the **`rust/icc`** module, resolving an **endianness issue** that caused **corrupted color transforms** when processing ICC profiles. Previously, the `u16_vec_to_bytes` function in `rust/icc/FFI.rs` incorrectly serialized `u16` data to little-endian bytes, while `skcms` expects this data (e.g., for A2B/B2A table-based curves or CLUT grid data) in big-endian format. The fix involves changing `to_le_bytes()` to `to_be_bytes()` to ensure proper data serialization for **ICC profile parsing**. Additionally, a new ICC profile (`apng19.png`) was added as a test resource, and the `RustIcc_equivalence_with_skcms_resource_files` test was enhanced to perform thorough byte-by-byte comparisons of curve entries and grid data, improving the robustness of **color management** validation.

This commit introduces **incremental and streaming decode support** for **BMP images** within the `SkBmpRustCodec`. It enables progressive loading of BMPs, particularly for network streaming, by leveraging a new resumable decoder API in the Rust `image` crate and updating the Rust toolchain. The **Rust FFI** now buffers decoded pixels and exposes them efficiently, while the **C++ `SkCodec` implementation** handles incremental decoding, subsetting, and **ICC color profile extraction** using `skcms_Transform`. This **new capability** significantly enhances the flexibility and performance of BMP decoding in scenarios where data arrives piecemeal, reducing cross-language overhead. Comprehensive tests for incremental decoding, streaming, and ICC profile handling have also been added.

This commit implements a **bug fix** within the `SkStreamAdapter` component, specifically addressing an issue with its `seek_relative` method. Previously, the **BMP decoder**'s use of `std::io::Seek::stream_position()` would trigger a zero-offset seek, which Chromium's `SegmentStream` incorrectly rejected. The fix modifies `SkStreamAdapter::seek_relative` in `rust/common/SkStreamAdapter.cpp` to prevent calling the underlying stream's `move` operation when the requested offset is zero. This ensures robust stream handling and prevents failures when decoding **BMP images** in environments that utilize `SegmentStream`, such as **Chromium**.

This commit performs a **refactoring** and **dependency update** within the **Rust ICC module**. It **updates the `moxcms` crate to version 0.8.0** and **eliminates previously replicated private code** for handling parametric curve parameters. Instead, the `rust/icc/FFI.rs` module now directly utilizes the public `moxcms::ParametricCurve` API for curve conversion logic, specifically impacting functions like `parametric_curve_to_transfer_function`. This change improves **code maintainability** by leveraging the upstream library's official implementation, thereby **reducing redundancy** in the color management subsystem.

This commit delivers **bug fixes** and **improvements** to the **`rust_icc` profile parsing library**, addressing several known gaps in its initial implementation. It enhances the `rust/icc/FFI.rs` module to correctly support a broader range of **ICC parametric curve types** and properly interpret **empty curve tables** as linear/identity functions. Furthermore, it adds crucial **A2B/B2A transform validation** and correct application of encoding factors, ensuring more accurate and robust parsing of ICC profiles. These corrections enable the `RustIcc_equivalence_with_skcms_resource_files` test to fully validate `rust_icc`'s parsed structures against `skcms`.

This commit introduces an **initial implementation** of a **Rust FFI layer** for **ICC profile parsing**, leveraging the `moxcms` crate. It provides the **color management** and **codec subsystems** with the ability to parse ICC profiles using Rust, converting them into `skcms`-compatible data structures via `rust/icc/FFI.rs` and its C++ FFI wrappers. This **new capability** required extensive updates to the **build system (GN and Bazel)** to integrate the Rust module and its dependencies, including a new `skia_use_rust_icc` flag. This foundational work prepares the project for **future integration of Rust-based ICC parsing into rustified image codecs**, enhancing color profile handling.

This commit **relays the initial implementation of a Rust-based BMP decoder** for Skia, introducing a **new experimental feature** aimed at providing a memory-safe alternative to the existing C++ decoder. It integrates the `image-rs` crate via a **Rust FFI layer** and a **C++ integration layer** (`SkBmpRustCodec`), while intentionally omitting support for embedded JPEG/PNG to simplify its architecture. The **build system** (GN and Bazel) is updated to support this new component, which can be enabled via the `skia_use_rust_bmp_decode` flag, and includes dedicated **unit tests and fuzzing**. This work significantly expands Skia's **image decoding capabilities** with a modern, memory-safe approach.

This commit introduces an **experimental new capability** to Skia: a **Rust-based BMP decoder**, providing a memory-safe alternative to the existing C++ implementation. This **new feature** leverages the `image-rs` crate and integrates into **Skia's image decoding subsystem** via a C++ FFI layer (`SkBmpRustCodec`), affecting how BMP images are processed. It is conditionally compiled using the `skia_use_rust_bmp_decode` flag and intentionally drops support for embedded JPEG and PNG to simplify its architecture. The change includes **build system updates** for Bazel and GN, along with comprehensive **unit tests** (`SkBmpRustDecoderTest.cpp`) and a **fuzzer** (`FuzzBMPRustDecoder.cpp`) to ensure its robustness.

This commit performs a **maintenance refactoring** of the **Rust build process** within the **Bazel build system**. It **consolidates multiple Rust Bazel build actions** defined in `BUILD.gn` into a single unified `rust_all_ffi_bazel_build` action. This change prevents **symbol duplication** from `std/core` Rust libraries that previously occurred when each action generated its own static library, ensuring a single static library is produced for all Rust FFI targets. The `gn/bazel_build.py` script was also updated to support building multiple targets in this consolidated manner, leading to a more robust and efficient build for Rust components by ensuring **correct linking of Rust FFI targets**.

This commit performs **build system maintenance** by adjusting dependencies within the **Rust CXX FFI integration** to ensure correct build order. It explicitly adds a dependency from the `rust_common` module to the `rust_cxx_core_bazel_build` action, guaranteeing that the critical `cxx.h` header is generated before `rust_common` compilation. Concurrently, an unnecessary dependency from the `png cxx_bridge` to `rust/common:ffi_utils` is removed, streamlining the build graph. This change also involves a **refactoring** of the build target name from `rust_png_cxx_core_bazel_build` to `rust_cxx_core_bazel_build` in `BUILD.gn`, impacting `png_decode_rust` and `png_encode_rust` to use the new, more general target.

This commit **refactors** the **Rust FFI stream adaptation** by extracting the `Read` and `Seek` trait implementations, previously specific to `rust/png`, into a new **`rust/common`** module. This centralizes the `SkStreamAdapter` C++ implementation and its Rust FFI bindings (`io_traits_ffi.rs`) to promote **code reuse** across various image codecs. The **`rust/png`** module is updated to utilize these new common utilities, removing its redundant local `ReadAndSeekTraits` implementation. This **architectural improvement** standardizes how **`SkStream`** is exposed to Rust as `Read` and `Seek` traits, enabling other Rust-based codec implementations (e.g., BMP, JPEG) to leverage this shared infrastructure and reducing future code duplication.

This commit **creates the foundational build system integration for Rust common FFI utilities** within Skia, specifically for Chromium's GN. It introduces a **new `gn/rust.gni` file** to define variables for Rust common FFI source files and updates **Bazel targets in `rust/common/BUILD.bazel`** to define new `rust_cxx_bridge` and `rust_library` targets. This work also **refactors existing `span_utils` references to `ffi_utils`** across various GN and Bazel files, establishing the necessary infrastructure for sharing Rust code. This **preparatory step** enables the integration of Rust common FFI utilities into Chromium's build system and is a prerequisite for refactoring the `rust/png` module to use these common traits.

This commit performs a significant **refactoring** of the project's Rust integration utilities by **moving and renaming** the `UtilsForFFI.h` header to `rust/common/SpanUtils.h`. This change centralizes common **FFI utility functions** into a new, shared `rust/common` module, making them accessible to multiple Rust-based codecs. The **Bazel** and **GN build configurations** are extensively updated across various files, including `src/codec/BUILD.bazel` and `gn/codec.gni`, to reflect the new location and ensure proper linking for existing Rust PNG components. This **maintenance** work is crucial for **enabling future Rust implementations**, such as a new BMP decoder, by providing a common set of tools.