Re: ListBox does not display SelectedItem the first time when ItemsSource are value types

07-01-2009 4:56 AM |

Hi HiPerFreak,

We reproduced your issue with your code. As a workaround, we can change your code like below.

DemoPresentationModel.cs

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Collections.Generic;
using System.ComponentModel;

namespace ListBoxBugDemo
{
  public class DemoPresentationModel : INotifyPropertyChanged
  {
    private List months;
    private Data selectedMonth;

    public List Months
    {
      get { return this.months; }
    }

    public Data SelectedMonth
    {
      get { return this.selectedMonth; }
      set
      {
        if (this.selectedMonth != value)
        {
          this.selectedMonth = value;
          OnPropertyChanged("SelectedMonth");
        }
      }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public DemoPresentationModel(Page view)
    {
        this.months = new List() { new Data(1), new Data(2), new Data(3), new Data(4) };
        this.selectedMonth = months[1];
        view.Model = this;
      
    }

    protected virtual void OnPropertyChanged(string propertyName)
    {
      if (PropertyChanged != null)
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

  }

  public class Data
  {
      public Data(int i)
      {
          this.I = i;
      }
      public int I { get; set; }
      public override string ToString()
      {
          return this.I.ToString();
      }
  }
  
}

Page.xaml.cs 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace ListBoxBugDemo
{
  public partial class Page : UserControl
  {
    public Page()
    {
      InitializeComponent();
      Loaded += new RoutedEventHandler(Page_Loaded);
    }

    void Page_Loaded(object sender, RoutedEventArgs e)
    {
        
    }

    public DemoPresentationModel Model
    {
      get { return DataContext as DemoPresentationModel; }
      set { DataContext = value; }
    }

    private void HandleShowSelectedClick(object sender, RoutedEventArgs e)
    {
      MessageBox.Show("listBox.SelectedItem = " + listBox.SelectedItem);
    }

    private void HandleSetTo11Click(object sender, RoutedEventArgs e)
    {
        DemoPresentationModel dpm = (DemoPresentationModel)this.DataContext;
        listBox.SelectedItem = dpm.Months[2];
    }
  }
}

Please add the styles and have a try.  If it doesn't work, please share the demo just as you did on your initial post.  Thanks

Best regards,

Jonathan 

 

Re: ListBox does not display SelectedItem the first time when ItemsSource are value types

07-02-2009 4:48 AM |

Hi HiperFreak,

Ok. If you are using Silverlight 2, it won't work if we use ImplicitStyleManager just as you did in your last demo.  The workaround is move new DemoPresentationModel(view); from App.xaml.cs to Page_Loaded event.  For example,

   void Page_Loaded(object sender, RoutedEventArgs e)
    {
         new DemoPresentationModel(this);
    }

By the way,  this issue will be fixed with the coming up Silverlight 3 RTW.  Actually, I have updated my Silverlight 3 beta environments to Silverlight 3 (3.0.40624.0 , for internal only) and your sample works pretty well with Silverlight Toolkit for Silverlight 3.   So, just do some tiny modifications and waiting for the RTW version.  By the way, I cannot assure you the release date.   Thanks.

Best regards,

Jonathan