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craft-libs/crates/psd/src/tiff
f462bb8128 craft-psd: deferred global blocks and a merged-image preview (ported from PhotoCraft) (#1037)
* craft-psd: Photoshop PSD/PSB reader and writer, moved from PhotoCraft

PhotoCraft's `photocraft-psd` crate (crates/psd at storytold/photocraft
63b641b55e54bf8f5c83efd977fdb16a2c255431) as `craft-psd`: the lossless
PSD/PSB model, reader, writer and builder, descriptors, the Photoshop
resource files that share its primitives (.abr, .asl, .aco, .act, .ase,
.grd, .pat, .atn, .csh, .shc) and the Photoshop blocks of a layered TIFF.
The crate had no dependency on any other PhotoCraft crate.

Code is unchanged apart from the crate name, craft-libs' rustfmt width,
comments that named other PhotoCraft crates, issue references (now
`photocraft#N`), and the corpus tests' directory (`CRAFT_PSD_CORPUS` or
`corpus/` at the workspace root). Tests, proptests, fuzz targets and
fixtures move with it.

Part of #778, #786.

* craft-psd: engine_data, the text engine document of type layers

The EngineData reader and writer from PhotoCraft's photocraft-text
(crates/text/src/engine_data.rs at storytold/photocraft 63b641b5): a
tree of values that is written back in Photoshop's layout, with strings
stored as plain bytes kept as plain bytes.

From EffectCraft's effectcraft-psd (crates/psd/src/engine_data.rs at
storytold/effectcraft 072e1af9), ported onto that tree: `first_style`,
the first style run as a typed `TextStyle` with bounded sizes and
spacings, and `minimal`, a one-run document for writers and fixtures.
`Value::index` is new.

Both apps had their own parser for the same syntax.

* craft-psd: engine_data::parse_lossy reads what it can of a damaged document

EffectCraft's EngineData reader was best effort: a truncated or damaged
document still gave the text and style it held. `parse_lossy` does that
on the same parser: a truncated dictionary, array or string keeps what
it has, a byte that starts no key is skipped, a token that is no number
becomes a name, and garbage gives an empty dictionary. `parse` stays
strict and is unchanged in what it accepts.

The parser's `value` is split into one function per kind of value, and
reads with `get` instead of indexing.

* craft-psd: typed views of type layers, smart objects and adjustments

Read-only views EffectCraft's effectcraft-psd had over the blocks this
crate keeps raw (storytold/effectcraft f334bcf3, crates/psd/src/parse.rs
and placed.rs). The blocks stay raw and write back unchanged.

- `text`: `TypeLayer` from `TySh`: text, transform (the identity when not
  finite), bounds, the first style run (read with
  `engine_data::parse_lossy`) and the text descriptor.
  `LayerRecord::type_layer`.
- `smart`: `SmartObject` from `SoLd`/`SoLE` (id, quad, non-affine
  transform, size, warp) and `PlLd`; `Warp` with the named styles and the
  custom quilt mesh; the quad geometry (`map`, `placed_bounds`,
  `placed_size`, `bake_scale`, `placement`). `LinkedFile` and
  `linked_files` for `lnk2`/`lnkD`/`lnk3`/`lnkE`, `PsdFile::linked_files`
  and `PsdFile::linked_data`. `LayerRecord::smart_object`.
- `adjust`: `Adjustment` from `nvrt`, `brit`, `CgEd`, `hue2`/`hue `,
  `levl`, `expA`, and the other adjustment keys by name;
  `LayerRecord::adjustment`, `solid_color` (`SoCo`) and `effects` (`lfx2`).
- `Descriptor`: `object`, `number`, `numbers`, `boolean`, `text`,
  `enumerated`, `raw_data`, `color`; `Value::as_number`.

Linked-file data is a range of the block's data, checked against the
record, instead of a range of the whole file.

* craft-psd: shared descriptor lookups

Descriptor::get_bool, get_number, get_text, get_enum and get_object,
used by asl, grd and slices in place of their own copies.

Ported from storytold/photocraft#9552 (its crates/psd part).

* craft-psd: the typed views use the shared descriptor lookups

One set of Descriptor accessors: the get_* lookups from photocraft#9552.
numbers, raw_data and color move next to them as get_numbers,
get_raw_data and get_color.

* craft-psd: global blocks can stay in the source, and a preview of the merged image

- `PsdFile::from_source_deferring` leaves the data of each global block a
  callback picks in the source (`TaggedBlock::stored`), so an embedded
  smart-object file that is most of a PSD is not read on open.
  `TaggedBlock::encoded`, `encoded_data_len` and `load` give the data
  wherever it is; writing copies it from the source; equality compares the
  bytes, and the same range of the same source without reading it.
  `parsed` refuses a block still in the source.
- `FileSource` fails a read after the file changed in place (length or
  modification time), instead of mixing old offsets with new bytes.
- `PsdFile::merged_preview(max_side)` samples every k-th row and pixel of
  a raw or RLE RGB/gray merged image, 8/16/32-bit (32-bit encoded to sRGB),
  reading a few megabytes of a large file. `ImageData::row_decoder` decodes
  the merged image's rows on their own.

Ported from storytold/photocraft#11586, which contains #6589 and #6616's
crates/psd changes (photocraft#5106).

* craft-psd: linked files read deferred blocks, and the preview size is capped

- `PsdFile::linked_files` and `linked_data` read a linked-layer block
  through `TaggedBlock::encoded`, so a block left in the source is found;
  they return `Result`, and `linked_data` a `Cow` borrowed from a block in
  memory.
- `merged_preview` refuses an output over `MAX_DECODED_BYTES` before it
  decodes or allocates (the size is the caller's), and a failed allocation
  is `OutOfMemory`.

---------

Co-authored-by: Omar Saidahmed <osaidahm@uwaterloo.ca>
Co-authored-by: Phil Trinh <ptrinh@me.com>
2026-11-11 20:56:55 -05:00
..