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Dylan M. Taylor
a4b57d47b9
* Add craft-crs: Camera Raw crs: settings in XMP, read and written, from PhotoCraft The format half of PhotoCraft's Camera Raw settings files (crates/io/src/camera_raw_xmp.rs at abeb16c96): the crs: settings of an XMP packet as written, Camera Raw's number and curve point text, the crop and its orientation, a writer, and the toolkit marker. Which setting drives which control stays in the app. * craft-crs: structures carry their element and are written back Local corrections and other structured settings were dropped, and an rdf:Seq of descriptions read as empty strings. A structure now holds its crs: element, a sequence is only plain text items, descriptions inside a structure are not read as top-level settings, and to_xmp writes structures back. * craft-crs: read packets through craft-metadata's XMP reader One XMP reader for every crate: Settings::parse goes through craft_metadata::parse_xmp and Settings::from_xmp takes its XmpData. Settings are kept by name (the reader's map has no file order), structures are craft-metadata's XmpValue and are written back as rdf:parseType Resource elements and rdf:Seq arrays. toolkit stays a bounded first-start-tag scan, as the reader does not return x:xmptk.
36 lines
1.8 KiB
Markdown
36 lines
1.8 KiB
Markdown
# craft-crs
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Adobe Camera Raw settings: the `crs:` namespace (`http://ns.adobe.com/camera-raw-settings/1.0/`)
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in an XMP packet, as Camera Raw's Save Settings writes an `.xmp` settings file and as Camera Raw,
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Lightroom and Bridge write a raw file's sidecar.
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- `Settings::parse` reads a file; `Settings::from_xmp` takes a packet already read by
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`craft_metadata::parse_xmp`. Settings come back by name (`Exposure2012`), the last one winning
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where a name repeats: text from an attribute or a plain element, the plain items of an
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`rdf:Seq`, or a structure (`crs:GradientBasedCorrections` and other local corrections) as
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`craft_metadata`'s `XmpValue`, for the caller to read. The file's own prefixes do not matter.
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A description inside a structure belongs to the structure, not to the settings.
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- `number`, `signed` and `points`: Camera Raw's numbers (`+0.50`) and tone curve points
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(`"32, 22"`).
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- `Settings::crop`: the crop rectangle, only when `HasCrop` is `True`; straightened, inverted,
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empty or unreadable crops are reported as unusable with the keys present. `Crop::oriented` and
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`Crop::pixels` place it on an upright frame of a given size.
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- `Settings::to_xmp`: a settings file Camera Raw's Load Settings reads, structures included,
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naming the toolkit that wrote it; `toolkit` reads that name back.
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Which setting drives which control, and the ranges they clamp to, are the application's.
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## Limits
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| Limit | Value |
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| --- | --- |
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| Input | 4 MiB (`MAX_XMP_BYTES`) |
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| Nesting and size of the packet | `craft-metadata`'s XMP limits |
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| Structure depth written | 64 (`MAX_WRITE_DEPTH`) |
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## XMP
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Packets are read by `craft-metadata`'s XMP reader, the one every crate shares. `toolkit` reads
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only the `x:xmptk` attribute of the first `x:xmpmeta` start tag, with a bounded `craft-xml` scan,
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because that reader does not return it.
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