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Dylan M. Taylor
fa26a2a4c6
The format half of PhotoCraft's Paint.NET import (crates/io/src/pdn.rs and pdn/nrbf.rs at abeb16c96): the PDN3 header, the .NET binary serialization graph, the layer list and blend modes, and the chunked gzip pixel blocks. Surfaces, blend-mode mapping and warnings stay in the app.
34 lines
1.7 KiB
Markdown
34 lines
1.7 KiB
Markdown
# craft-pdn
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Paint.NET documents (`.pdn`), read. Only the PDN3 layout (Paint.NET 3 and 4): the `PDN3`
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signature, an XML header (skipped), a .NET binary serialization stream holding a
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`PaintDotNet.Document`, then one block of pixels per surface in numbered chunks, each a gzip
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stream or raw bytes. The layout follows the reader of the pypdn project (MIT); the serialization
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records follow Microsoft's public MS-NRBF specification.
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- `is_pdn`: the signature.
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- `Document::parse`: canvas size, bitmap layers (name, visibility, opacity 0 to 255, Paint.NET's
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own `BlendMode`, from the current `blendMode` field or the older `UserBlendOps` class names)
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and which surface each layer shows. Every allocation the pixels need is checked first.
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- `Document::read_surfaces`: decodes the pixel blocks in file order, one `Surface` (rows of
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B, G, R, A bytes, straight alpha) at a time, with a `keep_going` callback.
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- `nrbf`: the data-only MS-NRBF reader on its own: a `Graph` of `Value`s with references kept as
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ids. No .NET type is instantiated or run.
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Paint.NET's Color Burn and Color Dodge are its own formulas; what an application maps them to is
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its own choice. There is no writer.
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## Limits
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| Limit | Value |
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| --- | --- |
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| Canvas, and all pixel blocks together | 1 GiB (`MAX_PIXEL_BYTES`) |
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| Layers | 1 to 1024 (`MAX_LAYERS`) |
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| A layer name; all names | 64 KiB (`MAX_NAME_BYTES`); 4 MiB (`MAX_TOTAL_NAME_BYTES`) |
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| Pixel chunks in one block | 1,000,000 |
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| NRBF records, items and members | 1,000,000 (`nrbf::MAX_ITEMS`) |
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| NRBF string bytes | 64 MiB (`nrbf::MAX_STRINGS`) |
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| NRBF nesting and reference chains | 64 (`nrbf::MAX_DEPTH`) |
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A raw pixel block shorter than it declares is refused before its buffer is allocated.
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