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SilentYetiandClaude Opus 5.5
db0fb07862
Squashed onto main, with the maintainer's asks applied: - Photoshop's blend menus (layers, brush, pencil, gradient, layer style) stay as they are; the Layers panel and Blending Options list a Paint.NET mode only for a layer that uses one. - The six Paint.NET mode labels are translated in every catalog, and the blend-mode i18n test iterates layer_modes(). - pdn::pixels rejects truncated uncompressed (version 1) data before allocating its buffer. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
55 lines
3.6 KiB
Markdown
55 lines
3.6 KiB
Markdown
# Paint.NET documents
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PhotoCraft opens PDN3 `.pdn` files natively, without Paint.NET, Python, .NET or an external
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converter. File › Open, recent files, drops, the CLI and automation use the shared importer.
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The browser file picker also accepts `.pdn`.
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Each bitmap layer remains editable. Layer order, Unicode names, visibility, opacity and pixel
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alpha are retained. Painting, masks, transforms, reordering, duplication and undo use the same
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commands as other pixel layers. All 14 PDN3 blend modes are supported on the CPU and GPU.
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Reflect, Glow, Negation and XOR have no Photoshop equivalent, and Color Burn and Color Dodge have
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separate Paint.NET variants because their edge cases differ. The blend menus stay Photoshop's: a
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layer that uses one of these six modes lists its own mode after Photoshop's, and other layers don't
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show them.
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PDN support is **import only**. Save opens Save As and suggests `.pcraft`, which preserves the
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layers and every blend mode. Exporting as `.pdn` fails with an explanatory error. PSD cannot
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represent six Paint.NET variants; exporting those as PSD reports that their blending was
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changed to Normal. Use `.pcraft` for continued editing, and PNG for a flattened rendering.
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The reader supports PDN3's typed NRBF objects, both numeric and older blend-operation records,
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BGRA32 surfaces with padded rows, shared pixel memory, and gzip or raw numbered pixel chunks.
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It validates references, dimensions, strides, counts, chunk ranges and gzip checksums. Metadata
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object nesting is capped at 64, layers at 1024 and total decoded pixel memory at 1 GiB. Imports
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can be cancelled while parsing, decompressing or copying pixels. Unsupported layouts and
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versions return errors. Paint.NET document metadata (including print resolution and profiles)
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is currently omitted; nonempty user metadata produces an import warning. Layer data is preserved.
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## Verification
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Synthetic unit tests exercise every blend mode, names, hidden layers, opacity, alpha, row
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padding, reversed chunks, old/new mode records, native saves, cancellation and malformed data.
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The GPU parity tests include the additional modes. Local real-file checks are opt-in:
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```sh
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PDN_TEST_DIR=/path/to/pdn-and-png-exports cargo test -p photocraft-io --test pdn_corpus -- --ignored --nocapture
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PDN_TEST_FILE=/path/to/layered.pdn cargo test -p photocraft-engine --test pdn -- --ignored
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```
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Each PDN in `PDN_TEST_DIR` needs a corresponding `.png` export with the same basename. The
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test checks pixels against that export and verifies layer preservation through `.pcraft`.
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Keep real-file corpora outside the application repository.
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The local Paint.NET 4.0.10 corpus (14 small texture documents, 1–8 layers) also matches its
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embedded full-size previews within 2.142/255. Older Paint.NET rounded between layers; PhotoCraft
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keeps floating-point precision, so layered composites are not necessarily byte-identical.
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A supplied 5.x document (1280×720, 11 layers, header version `5.3.8488.42200`) passes editing,
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painting, undo/redo and native-save checks. Its embedded 256×144 preview matches a Catmull–Rom
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downsample of our rendering with mean error 0.418/255 and maximum error 8/255. Its neighboring
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PNG differs from the saved PDN preview, so it is unsuitable as a full-size rendering oracle.
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These checks do not establish compatibility with every Paint.NET release.
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Format references: [MS-NRBF](https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-nrbf/)
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and the [pypdn reader](https://github.com/addisonElliott/pypdn/blob/master/pypdn/reader.py).
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This reader implements the layout independently; it does not run .NET deserialization.
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