45 lines
2.2 KiB
Markdown
45 lines
2.2 KiB
Markdown
# pdfcraft-annot
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Comments (annotations), ISO 32000-2 §12.5. Layer L3, depends only on `pdfcraft-cos`.
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## What it does
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- **Builders** for the comment types Acrobat's commenting tools create: sticky note (`Text` +
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`Popup`), highlight, underline, strikethrough, squiggly, rectangle (`Square`), oval (`Circle`),
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line and arrow (`Line` with `/LE`), freehand drawing (`Ink`) and text box (`FreeText`).
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- **Appearance streams** (`appearance::build`) generated from the annotation dictionary, so new
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and restyled comments look the same in every viewer. Highlights multiply (`/BM /Multiply`).
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Note icons are PdfCraft's own drawings. Text boxes use standard Helvetica (WinAnsi), with
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line breaking by approximate Helvetica proportions (no font program is bundled).
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- **Edits:** reply (`/IRT`), set review status (a `/State` reply, as Acrobat's "Set status"
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does), change text, move, resize, restyle, delete (with pop-up and replies).
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## API sketch
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```rust
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let index = add_annotation(&mut doc, &NewAnnotation { page, shape, style, contents, author }, &meta)?;
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add_reply(&mut doc, page, index, "Agreed", "Ada", &meta)?;
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set_review_state(&mut doc, page, index, ReviewState::Accepted, "Ada", &meta)?;
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move_annotation(&mut doc, page, index, dx, dy, &meta)?;
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set_style(&mut doc, page, index, Some(rgb), Some(0.5), Some(2.0), &meta)?;
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delete_annotation(&mut doc, page, index)?;
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```
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A comment is addressed by `(page, index in /Annots)`, the same pair
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`pdfcraft_render::Annotation` reports. `Meta` carries the date and the `/NM` id so edits stay
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deterministic; the engine supplies them.
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## Fidelity rules
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- Unknown keys are kept. Inline annotation dictionaries are promoted to indirect objects only
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when an edit needs a reference to them.
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- `set_style` refuses (and changes nothing) when it cannot redraw the comment, e.g. stamps,
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cloudy borders or callouts, instead of leaving a stale appearance.
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- Replies get the parent's `/Rect` and an empty appearance: they appear in comment lists but
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never paint a second icon.
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## Not yet
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Callouts, polygons and polylines, clouds, carets (insert/replace text), stamps, file
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attachments, rich text (`/RC`, `/DS`), and the shared named-appearance cache Acrobat writes.
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