mirror of
https://github.com/storytold/craft-libs.git
synced 2026-11-12 08:52:32 +00:00
Dylan M. Taylor
473fe09862
* Add craft-kra: Krita archives, maindoc.xml and tiled pixel files, from PhotoCraft The format half of PhotoCraft's Krita import (crates/io/src/kra.rs and kra/tiles.rs at abeb16c96): the archive and its mimetype, maindoc.xml as a tree of nodes with the attributes Krita writes, the tiled pixel files and their LZF compression. The mapping onto a document (blend modes, surfaces, warnings) stays in the app. maindoc.xml is read with craft-xml and the archive with the zip crate. * craft-kra: a default pixel is read under a one-pixel limit The .defaultpixel member (1 to 8 bytes) was inflated under the 1 GiB layer-file limit before its size was checked. Ported from storytold/photocraft#11138. * craft-kra: the tile table is not reserved from the declared count A tiled file may declare one record per eight bytes of its size. Reserving that many up front is 3 GiB for a 1 GiB member that holds none of them. Reserve 65,536 records at first and grow as records are read, never past the declared count. Ported from storytold/photocraft#13309.
45 lines
2.2 KiB
Markdown
45 lines
2.2 KiB
Markdown
# craft-kra
|
||
|
||
Krita documents (`.kra`, `.krz`), read. Written from files Krita writes; no Krita code is used.
|
||
|
||
A Krita document is a ZIP whose first, stored entry is `mimetype` = `application/x-krita`. It
|
||
holds `maindoc.xml` (the node tree), one tiled pixel file per paint layer and mask under
|
||
`<image name>/layers/`, the ICC profile in `<image name>/annotations/icc`, and Krita's rendering
|
||
of the whole image in `mergedimage.png`.
|
||
|
||
- `is_kra`, `zip_mimetype`: recognise an archive by its first entry, without unzipping.
|
||
- `Archive::open`: checks the mimetype and reads `maindoc.xml` into an `Image` of `Node`s. Every
|
||
node kind is kept with the attributes the file has (`nodetype`, `compositeop`, `opacity`,
|
||
offsets, `colorspacename`, `filename`, masks, ...). No pixel is read.
|
||
- `Archive::layer_file`, `default_pixel`, `icc_profile`, `merged_image`: the other entries, each
|
||
with a size limit.
|
||
- `tiles::TileFile`: a tiled pixel file's header and tile table; `decode` gives one tile's
|
||
interleaved pixels. `tiles::lzf_decompress` is the LZF inside.
|
||
- `tiles::Space`: the pixel layouts read (`RGBA`, `RGBA16`, `GRAYA`, `GRAYAU16`, and one-byte
|
||
masks), with `rgba` and `samples` to turn Krita's B, G, R, A little-endian pixels into channel
|
||
order.
|
||
|
||
What a node kind, a composite operation or a colour space means to an application is not decided
|
||
here. There is no writer.
|
||
|
||
## Limits
|
||
|
||
| Limit | Value |
|
||
| --- | --- |
|
||
| Canvas side | 300,000 px (`MAX_SIDE`); offsets and tile positions up to four times that |
|
||
| Canvas area | 1 GiB at 8 bytes per pixel (`MAX_PIXEL_BYTES`) |
|
||
| `<layer>` nodes | 8192 (`MAX_NODES`) |
|
||
| `maindoc.xml` | 32 MiB, 512 levels of nesting, no internal DTD subset |
|
||
| A pixel file, inflated | 1 GiB (`MAX_LAYER_FILE`) |
|
||
| ICC profile | 16 MiB |
|
||
| Tile | 1024 × 1024 px, 64 bytes per pixel, header lines of 256 bytes |
|
||
|
||
A pixel file is decoded one tile at a time into a buffer the caller owns, so the memory a
|
||
document takes is the caller's to budget.
|
||
|
||
## ZIP
|
||
|
||
The archive is read with the `zip` crate directly. `zip_mimetype` (the leading stored `mimetype`
|
||
entry) and the bounded entry read are the same in every mimetype-first ZIP format and belong in a
|
||
shared ZIP crate once there is one.
|