THPDFHeadlessDocument.SetRichTextFieldValueWithAppearance

procedure SetRichTextFieldValueWithAppearance(FieldIndex: Integer;
  const Runs: THPDFHeadlessRichTextRuns;
  const Fonts: THPDFHeadlessRichTextFonts;
  const Options: THPDFHeadlessTextAppearanceOptions);

Replace an existing text field with synchronized plain and styled values, enable its RichText flag, and create actual Unicode appearances for every widget after complete transactional preflight

Fonts contains actual regular, bold, italic and bold-italic font bytes; unused style entries may be empty, while every style used by nonempty text requires its own valid font program

Native rich-text field behavior · Document API