function ReadingUnits: TPdfReadingUnits;
TPdfReadingUnitsReading units keep headings and figure alternate text whole, split paragraph text at sentence boundaries, preserve decimal points, and leave the reading cursor as a caller-owned array index
Use Rects with TPdfView.SetReadingHighlight and Language to coordinate visual highlighting with a TTS voice
var Units: TPdfReadingUnits;
begin
Units := Pdf1.ReadingUnits;
if Length(Units) > 0 then
PdfView1.SetReadingHighlight(Units[0].Rects, Units[0].Page);
end;