问从Adobe Reader的ActiveX控件中获取PDF文档的页码

EN

function EnumWindowProc(pHwnd: THandle; Edit: Integer): LongBool; stdcall;
    function GetWindowTxt(gwtHwnd: THandle): string;
    var dWTextBuf: PChar;
        TextLen: Integer;
    begin
      TextLen := SendMessage(gwtHwnd, WM_GetTextLength, 0, 0);;
      dWTextBuf := StrAlloc(TextLen + 1);
      SendMessage(gwtHwnd, WM_GetText, TextLen + 1, Integer(dWTextBuf));
      Result := dWTextBuf;
      StrDispose(dWTextBuf);
    end;

    function GetClassNameTxt(gcnHwnd: THandle): string;
    var dWClassBuf: PChar;
    begin
      dWClassBuf := StrAlloc(1024);
      GetClassName(gcnHwnd, dWClassBuf, 1024);
      Result := dWClassBuf;
      StrDispose(dWClassBuf);
    end;

begin
  Result := LongBool(True);
  if (GetClassNameTxt(pHwnd) = 'AVL_AVView') and (GetWindowTxt(pHwnd) = 'AVPageView') then
  begin
    TEdit(Edit).Text :=  GetWindowTxt(FindWindowEx(pHwnd, 0, 'RICHEDIT50W', nil));
    Result := LongBool(False);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  EnumChildWindows(AcroPDF1.Handle, @EnumWindowProc, LongInt(Edit1));
end;