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pdfcraft/crates/annot/README.md
T
Guillem Hermida 32ca91a31f M5: sticky notes stay upright where they are placed on rotated pages (#2583)
Notes and file attachments are saved with the NoRotate flag (/F bit 5),
but nothing honoured it: on a page with /Rotate the icon was fitted to
/Rect and turned with the page, and sat away from where it was placed.

The vendored renderer now honours NoRotate (hayro-interpret patch 37):
the appearance fitted to /Rect is turned against the page's rotation
about the rectangle's upper-left corner, which stays put (ISO 32000-2
12.5.3). Form fields and links stay in /Rect, where their click targets
come from. A counterrotated appearance, as stamps use, would be turned
twice by viewers that honour the flag.

Annotation::shown_rect gives the box the note is drawn in. The UI uses
it for hit-testing, outlines, moving, the hover pop-up, the Comments
panel flash and the edit composer; a resize maps it back to /Rect.
comment_add anchors an icon's displayed top-left at `at`, and
comment_list, doc_info and comment_edit use the drawn box.

This also covers the sticky-note part of #1869.
2026-10-17 11:52:14 +02:00

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pdfcraft-annot

Comments (annotations), ISO 32000-2 §12.5. Layer L3, depends on pdfcraft-cos, pdfcraft-fonts and pdfcraft-model.

What it does

  • Builders for the comment types Acrobat's commenting tools create: sticky note (Text + Popup), highlight, underline, strikethrough, squiggly, rectangle (Square), oval (Circle), line and arrow (Line with /LE), freehand drawing (Ink) and text box (FreeText).
  • Appearance streams (appearance::build) generated from the annotation dictionary, so new and restyled comments look the same in every viewer. Highlights multiply (/BM /Multiply). Note icons are PdfCraft's own drawings. Text boxes use standard Helvetica (WinAnsi), with line breaking by approximate Helvetica proportions (no font program is bundled). Text it can't draw (in a text box, callout, Fill & Sign text, measurement label or dynamic stamp's by-line; appearance::undrawable_text) is kept as typed and drawn as ?, and the comment is marked with the first such character (pdfcraft_fonts::UNDRAWN_MARK) so the engine reports the edit and flattening refuses to make it permanent. Two refusals (AnnotError::Undrawable): a redaction mark's overlay text, which becomes page content when applied; and a restyle or resize of a comment another program drew with a font that has those characters, whose appearance is kept rather than redrawn with ? (new text for it is taken).
  • Edits: reply (/IRT), set review status (a /State reply, as Acrobat's "Set status" does), change text, move, resize, restyle, delete (with pop-up and replies).

API sketch

let index = add_annotation(&mut doc, &NewAnnotation { page, shape, style, contents, author }, &meta)?;
add_reply(&mut doc, page, index, "Agreed", "Ada", &meta)?;
set_review_state(&mut doc, page, index, ReviewState::Accepted, "Ada", &meta)?;
move_annotation(&mut doc, page, index, dx, dy, &meta)?;
set_style(&mut doc, page, index, Some(rgb), Some(0.5), Some(2.0), &meta)?;
delete_annotation(&mut doc, page, index)?;
signature_image(&doc, page, index)?; // embedded image XObject of Fill & Sign signature/initials

A comment is addressed by (page, index in /Annots), the same pair pdfcraft_render::Annotation reports. Meta carries the date and the /NM id so edits stay deterministic; the engine supplies them.

Fidelity rules

  • Unknown keys are kept. Inline annotation dictionaries are promoted to indirect objects only when an edit needs a reference to them.
  • set_style refuses (and changes nothing) when it cannot redraw the comment, e.g. stamps, cloudy borders or callouts, instead of leaving a stale appearance.
  • Replies get the parent's /Rect and an empty appearance: they appear in comment lists but never paint a second icon.
  • Resizing a stamp changes its /Rect and preserves its original appearance and resources; viewers scale that appearance into the new rectangle. Locked stamps refuse the edit.
  • Picture stamps (a natural-size or explicit-rectangle image, a PDF page, or an image signature) and PdfCraft's rubber stamps counterrotate their appearance on rotated pages, so the picture or label reads upright as the page is displayed. Restyling a picture stamp keeps that appearance matrix. The rotation is the page's /Rotate at placement.
  • Sticky notes and file attachments are not counterrotated: they carry the NoRotate flag and their icon is drawn in an unturned 20 × 20 box. A viewer keeps them upright on a turned page, about the upper-left corner of /Rect (ISO 32000-2 §12.5.3). PdfCraft's renderer does so (vendored hayro-interpret patch 37), and Summary::no_rotate tells the UI where the icon is drawn.

Not yet

Callouts, polygons and polylines, clouds, carets (insert/replace text), stamps, file attachments, rich text (/RC, /DS), and the shared named-appearance cache Acrobat writes.