Get selected List Box item in user control from Window

Question

I have a User control with a list box.

This User control located on my window. how can I detect and get selected item from list box in user control?

I previously tried this but when i select an item from list box e.OriginalSource return TextBlock type.

  private void searchdialog_PreviewMouseDown(object sender, MouseButtonEventArgs e)
        {
            //This return TextBlock type
            var conrol= e.OriginalSource;
            //I Want something like this
            if (e.OriginalSource is ListBoxItem)
            {
                ListBoxItem Selected = e.OriginalSource as ListBoxItem;
                //Do somting
            }
        }

Or there is any better way that I detect list box SelectionChanged in From My form?

Answer 1

I think the best soution would be to declare an event on your user control, that is fired whenever the SelectedValueChanged event is fired on the listbox.

public class MyUserControl : UserControl
{
  public event EventHandler MyListBoxSelectedValueChanged;

  public object MyListBoxSelectedValue
  {
    get { return MyListBox.SelectedValue; }
  }

  public MyUserControl()
  {
    MyListBox.SelectedValueChanged += MyListBox_SelectedValueChanged;
  }

  private void MyListBox_SelectedValueChanged(object sender, EventArgs eventArgs)
  {
    EventHandler handler = MyListBoxSelectedValueChanged;
    if(handler != null)
      handler(sender, eventArgs);
  }
}

In your window, you listen to the event and use the exposed property in the user control.

public class MyForm : Form
{
  public MyForm()
  {
    MyUserControl.MyListBoxSelectedValueChanged += MyUserControl_MyListBoxSelectedValueChanged;
  }

  private void MyUserControl_MyListBoxSelectedValueChanged(object sender, EventArgs eventArgs)
  {
    object selected = MyUserControl.MyListBoxSelectedValue;
  }
}

Answer 2

there are a few ways to handle this:

1. Implement the SelectionChanged event in your usercontrol, and raise a custom event that you handle in your window:

   //in your usercontrol

   private void OnListBoxSelectionChanged(object s, EventArgs e){
       if (e.AddedItems != null && e.AddedItems.Any() && NewItemSelectedEvent != null){   
           NewItemsSelectedEvent(this, new CustomEventArgs(e.AddedItems[0]))
       }
   }
   

   //in your window

   myUserControl.NewItemsSelected += (s,e) => HandleOnNewItemSelected();
   

2. If you use binding or any form of MVVM, you can use a DependencyProperty to bind the selected item to an object in your viewmodel

   //in your usercontrol:

   public static readonly DependencyProperty CurrentItemProperty = 
    DependencyProperty.Register("CurrentItem", typeof(MyListBoxItemObject), 
   typeof(MyUserControl), new PropertyMetadata(default(MyListBoxItemObject)));
   
   public LiveTextBox CurrentItem
   {
       get { return (MyListBoxItemObject)GetValue(CurrentItemProperty ); }
       set { SetValue(CurrentItemProperty , value); }
   }
   

   //in your window xaml

   <MyUserControl CurrentItem={Binding MyCurrentItem} ... />