Module annot_appearance 

Appearance generation for markup & geometric annotations whose producer shipped no /AP stream (PDF 32000-1 §12.5.6).

Acrobat writes an appearance stream for every annotation, but many other producers leave the visual representation implicit in the annotation’s geometry properties (/QuadPoints, /Vertices, /L, /InkList, /C, /IC, …). A viewer is expected to synthesize the appearance from those. This mirrors the form-widget generator in crate::forms: it returns a GeneratedAppearance (a form XObject — /BBox, /Matrix, /Resources and a content byte stream) that the interpreter’s annotation painter replays exactly like a real /AP /N, so both render backends draw it with no backend changes.

The synthesized content is emitted directly in default user space (the same space as the annotation’s /Rect and geometry arrays), and the /BBox is set equal to the /Rect. The painter therefore maps /BBox onto /Rect as the identity and clips to the rectangle — geometry that extends past /Rect (as it should not, for a conforming file) is clipped, never scaled.

Supported subtypes: text markup (Highlight / Underline / StrikeOut / Squiggly, from /QuadPoints), geometric markup (Square / Circle / Line / Polygon / PolyLine / Ink), FreeText, a conservative Link border, Text note icons (a small vector glyph chosen by /Name), Stamp rubber-stamp badges (a bordered label decoded from /Name), a Caret insertion mark, and Redact redaction-region marks. Everything else (an existing /AP, Widget, Popup, a PDF 2.0 Projection — which has no defined default appearance — …) is left to its own appearance or the widget generator.

Functions

generate_annotation_appearance

Build a generated appearance for a markup / geometric annotation that has no /AP, or None when the subtype is unsupported or nothing should be drawn. dict is the annotation dictionary and rect its /Rect.