function UpdatePage;
Commits in-memory edits made through CreateAnnotation, AddImage, AddText, SetFormFieldFlagsAt, etc. to the underlying PDFium page.
Call after a batch of edits and before reading back the modified content or saving the document.
Wraps the corresponding PDFium API and exposes it as a TPdf instance member so consumers do not have to manage FPDF_DOCUMENT handles directly.
Pdf1.Active before calling page-scoped operations; methods that require an open document raise EPdfError otherwise.SaveAs to persist.
if Pdf1.Active then
Pdf1.UpdatePage;