[bobsingor]

A markup annotation's /RC is its comment (ISO 32000-2 §12.5.6.2). A comment draws nothing on the page, so it states its style over the reader's defaults: Acrobat writes a note's /RC with no body style at all. The parser read every annotation's /RC over its /DA and /DS, the base style a free text draws its text in.

Among the comment kinds, only a redact has a /DA, and it styles the overlay text ("CONFIDENTIAL"). So with a Courier 10pt red overlay:

• a redact comment that stated no font read as Courier 10pt red;
• a comment written in the default style read back as Courier 10pt red. The writer (Write a markup annotation's comment as rich text #110) leaves out what matches the reader's defaults, and the read then filled in the overlay's.

Now CPDF_RichTextParser::DefaultsFromAnnotation takes /DA, /DS, /Q and /TextColor only for a free text and a widget, whose rich text is the text they draw. Any other annotation's rich text reads over CPDF_RichTextStyle{}, the same defaults the comment writer compares against. EPDFAnnot_GetRichTextJSON, EPDFAnnot_SetRichTextJSON and EPDFAnnot_SetRichTextXHTML all go through it. Free text and form fields are unchanged, and a redact's overlay still reads from its /DA through EPDFAnnot_GetDefaultAppearance.

Pin this after embedpdf/embed-pdf-viewer#978. Main's engine still reads a redact's overlay font through EPDFAnnot_GetRichTextJSON; #978 reads it from /DA directly (EPDFAnnot_GetDefaultAppearanceFontFace). With this change and without #978, a redact whose overlay uses a registered font would read back as a standard font.

Tests

• RedactCommentReadsOverTheReadersDefaults, on a redact whose overlay is Courier 10pt red:

  • a comment written as JSON stores no body style and reads in the reader's defaults (no family, 12pt, black);
  • so does one imported from XHTML;
  • the overlay keeps its /DA.

  It fails without the change, on both the JSON and the XHTML write. It is recorded as a layer-mode writer (6 objects).

• On macOS: every *EPDFAnnot*, *RichText* and *Redact* embedder test passes (305, 2 skipped), and the 19 rich text unit tests pass. In layer mode, the 47 rich text and comment tests pass with no unknown writers. Linux CI hasn't run yet.