Lukasz Anforowicz

This commit **updates** the **Skia project's dependency** on the `png` Rust library from version `0.18.0-rc` to `0.18.1`. This **maintenance** task involves modifying the `MODULE.bazel` configuration to reflect the new version. The change ensures that **Skia's build system** and any **Rust components** relying on `png` for image processing are using the latest stable release. This update helps maintain compatibility and potentially incorporates upstream bug fixes or performance improvements from the `png` crate.

This **maintenance** commit **refactors** the conditional compilation within `gm/image.cpp` to support more flexible PNG codec configurations. Specifically, it enables the build system to correctly handle scenarios where the **Rust PNG encoder** is used in conjunction with the **libpng decoder**. This change enhances **build system testability** by allowing developers to exercise mixed codec implementations, which is crucial for validating build changes and ensuring robust support for various `skia_use_rust_png_*` and `skia_use_libpng_*` `args.gn` flags. The modifications primarily affect the `make_codec` and `new_texture_image` functions, ensuring `gm/image.cpp` can be built under these previously unsupported configurations.

This commit **fixes a bug** in the **Rust PNG codec** by restricting `sBIT` chunk handling to only 8-bit images within the `ToColor` function in `src/codec/SkPngRustCodec.cpp`. This prevents `SkEncodedInfo` assertions that could occur when `sBIT` data was incorrectly applied to higher bit-depth images. A **new test case**, `RustPngCodec_sbit565_ihdr16bits`, was added to `tests/SkPngRustDecoderTest.cpp` to verify the corrected `sBIT` behavior, particularly for 565-bit `sBIT` with 16-bit `IHDR` images. This improves the robustness of the **Rust PNG decoder** by preventing crashes during image decoding.

This commit performs **maintenance** on the **Rust PNG encoder** by removing an obsolete TODO comment from the `SkPngRustEncoderImpl` class. This **code cleanup** ensures that the internal documentation for the `SkPngRustEncoderImpl` implementation is up-to-date and accurate, reflecting that the previously noted task has been addressed. The change has no functional impact on the PNG encoding process, but improves the clarity and maintainability of the **image encoding subsystem**.

This commit performs **maintenance** by removing an obsolete TODO comment from the `tests/SkPngRustDecoderTest.cpp` file. The comment, which suggested APNG support was pending, is no longer relevant because **APNG decoding** has already been implemented in the `SkPngRustCodec` module. This cleanup improves the clarity and accuracy of the **test suite documentation** for the **Rust-based PNG decoder** without affecting any functional aspects of the decoder itself.

This commit **enhances the `fuzz` module** by introducing conditional support for PNG encoding within `FuzzMain.cpp`. It updates the `dump_png` function to dynamically select between the `SkPngRustEncoder` and the traditional `SkPngEncoder` based on the `SK_CODEC_ENCODES_PNG_WITH_RUST` build flag. This **feature improvement** removes a hard-coded dependency on `libpng`-based encoding, enabling more flexible **testing and validation of the Rust-based PNG encoder** within the fuzzing infrastructure. This change allows the fuzzer to comprehensively test different PNG encoding paths.

This commit **relands** a previous change to **update PNG encoder fuzzing infrastructure**, ensuring **fuzzer coverage for the new Rust-based PNG encoder** (`SkPngRustEncoder`). It modifies `fuzz/FuzzEncoders.cpp` to conditionally compile the `libpng`-based encoder fuzzer and introduces a new fuzzer entry point in `fuzz/oss_fuzz/FuzzPNGRustEncoder.cpp`. This **maintenance** work was made possible by a prior Chromium change, allowing the project to properly test both PNG encoding implementations and maintain robust **testing infrastructure**.

This commit **enhances the fuzzing infrastructure** by integrating the `SkPngRustEncoder` into `fuzz/FuzzEncoders.cpp`. It replaces a hard-coded dependency on the `libpng`-based `SkPngEncoder` with a conditional choice governed by `SK_CODEC_ENCODES_PNG_WITH_RUST`. This **maintenance** change introduces a new fuzzing target, allowing for more comprehensive testing of the **Rust-based PNG encoder** implementation. The update improves the flexibility and coverage of the **PNG encoding subsystem's fuzzing**, enabling testing of different encoder backends.

This commit **refactors** the **PNG encoding** infrastructure by **removing** the `SkXPSLibpngHelpers.h` and `SkXPSRustPngHelpers.h` helper files and their associated build system components. It replaces their usage, notably in `dm/DMSrcSink.cpp`, with inline lambda functions provided by callers, thereby **simplifying** the code and reducing the API surface. This **maintenance** effort streamlines **Skia's build configuration** and aligns with similar removals in Chromium and PDFium, resulting in a **cleaner and more maintainable codebase** without functional changes.

This commit **refactors the SVG subsystem** to **decouple `SkSVGDevice` from a hard-coded `libpng` dependency**, enabling more flexible PNG encoding. It introduces an `EncodePngCallback` via `SkSVGCanvas::Options` to allow **dependency injection of PNG encoders** into `SkSVGCanvas::Make` and `SkSVGDevice`. This **maintenance** change allows `SkSVGDevice` to use either `SkPngRustEncoder` or `SkPngEncoder` without direct knowledge, improving modularity and supporting `libpng`/Rust-agnostic PNG generation for SVG. The `SkSVGCanvas` API is updated to accept these options, and `SkSVGDevice.cpp` is refactored to utilize the injected callback, removing its previous hard-coded dependency. This **new capability** enhances the flexibility and testability of PNG encoding within SVG generation.

This commit **refactors Skia's PNG encoding infrastructure** by **removing the `SkXPSLibpngHelpers.h` and `SkXPSRustPngHelpers.h` files** and their associated build system components. It replaces their usage in modules like `dm/DMSrcSink.cpp` with direct lambda-based PNG encoding, simplifying the codebase. This **maintenance** effort streamlines Skia's build configuration, eliminates unnecessary header dependencies, and aligns with prior removals in Chromium and PDFium. The change primarily impacts the **XPS subsystem's PNG handling** and the overall build system, reducing complexity and improving maintainability.

This commit introduces a **new feature** to the **PNG encoding mechanism** within the `SkWriteBuffer` module, allowing for a flexible choice of encoder. It modifies `src/core/SkWriteBuffer.cpp`, specifically within the `serialize_image` function, to conditionally utilize the `SkPngRustEncoder` instead of the previously hard-coded `libpng`-based `SkPngEncoder`. This change enables the build system to select the **PNG encoding backend** by checking the `SK_CODEC_ENCODES_PNG_WITH_RUST` flag, providing greater control and modularity for image serialization.

This commit performs a **maintenance refactoring** by **removing the `SK_API` macro** from specific `inline` PNG encoding helper functions. It modifies the `SkXPS` documentation headers, specifically `include/docs/SkXPSLibpngHelpers.h` and `include/docs/SkXPSRustPngHelpers.h`, to remove `SK_API` from the `EncodePngUsingLibpng` and `EncodePngUsingRust` declarations. This change resolves **build errors** that arise when `SK_API` is incorrectly applied to `inline` functions, ensuring the **SkXPS PNG encoding utilities** compile correctly. The fix is crucial for downstream projects, like Chromium, that integrate these headers and rely on their proper compilation.

This commit implements a **documentation fix** within the **SkXPSDocument API** to correct an inaccurate comment. Specifically, it updates the description for the `SK_DISABLE_LEGACY_XPS_FACTORIES` macro in `include/docs/SkXPSDocument.h`. The comment now correctly states that certain behavior occurs when the macro "isn't set," rather than "is set," providing accurate guidance for developers. This minor **maintenance** update improves the clarity and precision of the **XPS document generation** configuration documentation.

This commit **introduces a new `detachAsVector` method** to the **`SkDynamicMemoryWStream` class**, a **new capability** that allows the stream's accumulated data to be efficiently detached and returned as a `std::vector<uint8_t>`. This enhancement to the **`SkStream` module** is designed to **facilitate the removal of `BufferWStream` from downstream projects like Chromium and PDFium**, thereby simplifying their stream data handling. The change includes the method's declaration in `include/core/SkStream.h`, its implementation in `src/core/SkStream.cpp`, and a dedicated test case in `tests/StreamTest.cpp` to ensure correctness. A release note entry for `relnotes/SkDynamicMemoryWStream-detachAsVector.md` is also included.

This commit **resolves a linking error** that prevented PDFium from utilizing the `SkPngRustEncoder` during XPS document generation. It introduces a **new capability** within the **XPS subsystem** by allowing configurable PNG encoding, specifically enabling the use of the Rust-based encoder. This is achieved by defining `SkXPS::Options` to specify an encoder callback and adding helper functions like `EncodePngUsingRust` for `SkXPSDevice` and `SkXPSDocument`. The **build system** (GN, Bazel) is updated to expose these new helpers, thereby **unblocking PDFium integration** and providing more flexible PNG encoding for XPS output.

This commit **introduces new public API overloads** for **`SkPngRustEncoder`**, allowing direct encoding of **`SkPixmap`** and **`SkImage`** into **`SkData`**. These **`EncodePngAsSkData`** functions, previously internal to Chromium, are now exposed in Skia's official API to facilitate **code reuse** and enhance **API consistency** with other Skia encoders. This **new capability** streamlines PNG encoding workflows for consumers of the Rust-based encoder, offering a unified interface that benefits projects like Chromium and PDFium.

This commit provides a **bug fix** within the **SkEncodedInfo** module by correcting an **implicit integer cast** in the `VerifyColor` function. Specifically, it changes the type of the `bitsPerComponent` parameter from `uint8_t` to `int` in `include/private/SkEncodedInfo.h`. This resolves a regression introduced in a previous commit, ensuring type safety and **unblocking the Chromium roll**. The fix prevents potential issues arising from incorrect type conversions in color verification logic, maintaining the integrity of **PNG encoding** operations.

This commit **refactors** the **Skia library's `SkEncodedInfo` component** to address a `-Wcovered-switch-default` compiler warning that occurred during standalone Pdfium builds. It extracts existing color verification logic into a new static helper function, `VerifyColor`, and modifies the `componentCount` method to remove a redundant default case. This **maintenance refactoring** is purely cosmetic, eliminating a build-time warning without affecting generated code, functional behavior, or performance. The changes are confined to `include/private/SkEncodedInfo.h`, improving code hygiene within the `SkEncodedInfo` class.

This commit **fixes a critical bug** in the **PNG decoding** module, specifically within the `blendAllRows` function in `src/codec/SkPngRustCodec.cpp`. Previously, when processing **animated PNG frames** that were sub-rectangles of a larger image, `subspan` could be called with an offset exceeding the buffer's bounds, leading to an out-of-memory access and a crash. The **bug fix** ensures `subspan` arguments are correctly constrained using `std::min`, preventing these crashes and improving the robustness of **animated PNG playback**. A new test case, `RustPngCodec_crbug445556737`, has been added to validate this fix.