Write Text on Pdf

function dicituraFissa(szNomeFile:pchar):boolean;
var StampMetaCan : TMetafileCanvas;
    aForm : TXForm;
    x,y,nrP: integer;
    lst :TStringlist;
    n,idx:integer;
    sz:String;
    wp :TWPViewPDF;
    StampMeta : TMetaFile;
begin
     wp:=TWPViewPDF.CreateParented(application.handle);
      wp.LoadFromFile(strpas(szNomeFile)) ;
      if true then
      begin
          StampMeta:=TmetaFile.create;
          StampMetaCan := TMetafileCanvas.Create(StampMeta,0);
          try
               StampMetaCan.Font.Height := -10;
               StampMetaCan.Font.Color := clBlack;
               StampMetaCan.Font.Name := 'Arial';
               StampMetaCan.Brush.Style := bsClear;
               aForm.eM11 := 1;
               aForm.eM12 := 1;
               aForm.eM21 := 1;
               aForm.eM22 := 1;
               aForm.eDx := Screen.PixelsPerInch;
               aForm.eDy := Screen.PixelsPerInch*2;
               SetWorldTransform(StampMetaCan.Handle, aForm);


               nrP:=wp.CommandEx(COMPDF_GetPageCount,0);
                y:=WPCentimeterToPixel(28,72);
                x:=WPCentimeterToPixel(1,72);


                lst:=TStringlist.create;
                lst.text:=strpas('Try write text on pdf');
                idx:=0;
                for n := lst.count - 1 downto 0 do
                begin
                   StampMetaCan.TextOut(x,y-(15*(n+1)), lst[idx]);
                   inc(idx);
                end;
                lst.free;


          finally
               StampMetaCan.Free;
          end;
                wp.CommandStrEx(495,inttostr(nrP)+'-'+inttostr(nrP), StampMeta.Handle)
          wp.Plus.SetSecurityMode(wpNoSecurity);
          wp.Plus.SaveToFile('C:\tmp\test.pdf');
          StampMeta.free;
      end;
      wp.free;
end;