ThumbHash

Added

• Added explicit srcset rendering support for responsive <picture> elements where each <source>/fallback <img> uses its own asset hash via child data-thumbhash attributes.
• Added JavaScript decoder coverage for srcset rendering, child-specific aspect ratios, dynamic DOM insertion, invalid child hashes, and compatibility with existing shared picture behavior.

Changed

• Refactored the client decoder around render roots so srcset picture parents coordinate child hashes without treating those children as standalone background placeholders.

Fixed

• Isolated invalid srcset child hashes so one bad child placeholder does not prevent valid sibling placeholders from rendering.
• Preserved existing shared picture behavior for child elements that provide their own data-thumbhash render settings.

Added

• PHP unit and integration test suites (Codeception).
• JavaScript decoder test suite (Vitest).
• Static analysis passing at PHPStan level 7.

Fixed

• Fixed CRC32 and Adler32 checksum calculations in the client-side PNG encoder for improved data integrity. Replaced the fragile nibble-based inline CRC and interleaved Adler32 with standard full-table CRC32 and a dedicated Adler32 pass over a pre-built scanline buffer.

Breaking Changes

• data-thumbhash-bg is no longer supported.
• Background placeholders must now use data-thumbhash with data-thumbhash-render="bg".
• The client decoder now supports explicit render modes (bg, picture, img) and defaults to bg unless overridden.

Added

• New Twig helper: thumbhashTransparentSvg(width = 4, height = 4).
• New setting: renderMethod (bg, picture, img).
• New setting: scriptPosition (head, end).
• Picture placeholder propagation support for <picture data-thumbhash ...> wrappers.
• Introduced ratio cropped PNG placeholders for better aspect ratio handling and reduced layout shift for both the frontend JS decoder and backend generated data URLs.

Changed

• Inline decoder config now includes renderMethod.
• Background placeholder behavior is now tied to the bg render mode instead of a dedicated data-thumbhash-bg attribute.

Upgrade Guide

• Replace all data-thumbhash-bg="..." usages with data-thumbhash="..." data-thumbhash-render="bg".
• If your implementation depends on setting <img src> from the hash, set data-thumbhash-render="img" per element, or set 'renderMethod' => 'img' globally.
• No database or migration changes are included in this release.
• schemaVersion remains 1.0.0.

• Initial release