private void OnAdd()
        {
            user = Serializer.DeserializeUser();
            int count  = 0;
            int number = -1;

            CurrentPicture = new Picture(uri, Title, Description);
            CurrentPicture.Validate();
            if (CurrentPicture.IsValid)
            {
                user.Pictures.Add(new Picture(uri, Title, Description));
                PictureViewModel.picturesChange(user);
                allUsers = Serializer.Deserialize();
                foreach (Users tempuser in allUsers.Users)
                {
                    if (tempuser.Username == user.Username)
                    {
                        number = count;
                    }
                    count++;
                }
                allUsers.Users[number].Pictures.Add(CurrentPicture);
                Serializer.SerializeUser(allUsers.Users[number]);
                Serializer.Serialize(allUsers);
                Title       = "";
                Description = "";
                Bitmap bitmap = (Bitmap)Bitmap.FromFile(@"C:\Users\pc\Desktop\Blok5-Projekat1\MVVM1\bin\Debug\addLogo.png", true);
                ButtonSource = BitmapConversion.BitmapToBitmapSource(bitmap);
            }
        }
        public void Login()
        {
            bool valid = false;

            currentUsers = Serializer.Deserialize();

            foreach (Users user in currentUsers.Users)
            {
                if (CurrentUser.Username == user.Username && CurrentUser.Password == user.Password)
                {
                    curUserLog = user;
                }
            }

            CurrentUser.ValidateLogin(currentUsers);
            if (CurrentUser.IsValid)
            {
                MenuViewModel.mode = "l";
                Application.Current.MainWindow.Content = new MenuViewModel();
                //MenuViewModel.current = curUserLog;
                Serializer.SerializeUser(curUserLog);
                PictureViewModel.picturesChange(curUserLog);
            }
        }