procedure TForm1.Demo_TgtPDFCaretAnnot;
var
  gtPDFCaretAnnot1: TgtPDFCaretAnnot;
  Size1: TSize;
  X1, Y1, X2, Y2: Double;
  gtPDFEngine1: TgtPDFEngine;
begin
  gtPDFEngine1 := TgtPDFEngine.Create(Nil);

  with gtPDFEngine1 do
  begin
    Preferences.ShowSetupDialog := False;
    Preferences.OpenAfterCreate := True;
    FileName := 'caret_annotation.pdf';

    // Store coordinates of the textout
    X1 := 1;
    Y1 := 1;

    // Obtain size of correct text in
    // textout in the current font size
    Size1 := TextSize('Hello', Font);

    // Store coordinates of the caret
    // - just below the textout
    X2 := X1 + (Size1.cx / 96);
    Y2 := Y1 + (Size1.cy / 96);

    // Create an caret annotation
    gtPDFCaretAnnot1 := TgtPDFCaretAnnot.Create;
    gtPDFCaretAnnot1.Rect := gtRect(X2, Y2, X2 + 0.1, Y2 + 0.1);
    gtPDFCaretAnnot1.Title := 'Document review';
    gtPDFCaretAnnot1.Subject := 'Spelling mistake 1';
    gtPDFCaretAnnot1.Contents :=
      'Your "Hello, world!" is not spelled correctly';
    gtPDFCaretAnnot1.BorderColor := clRed;

    BeginDoc;
    // Write textout
    TextOut(X1, Y1, 'Helloo, world');
    // Add caret annotation
    AddAnnotItem(gtPDFCaretAnnot1);
    EndDoc;
  end;
end;