Skip to main content

C# WPF Snippet - Synchronizing Selection [Beginner]


This is a short snippet on a cool little property for anything that derives from Selector (combo box, list box, etc..) called IsSynchronizedWithCurrentItem. This property allows multiple items controls that are bound to the same collection (on their ItemsSource property) to also display the same selection. This means that whatever is selected in one ItemsControl will be shown as selected in the other.

Below is a screenshot of the extremely simple sample app we will be creating today. It has a combo box and a list box which are both bound to the same backing collection. Granted, this is hard to convey in a screenshot, but if you change the current selection in either the combo box or the list box, the selection also changes in the other.


Selection Sync Screenshot

By default, the value of this property is null, which essentially means 'maybe'. Most of the time, the 'maybe' resolves to false, unless the Selector is using a CollectionView, in which case it resolves to true. If you explicitly set the property to true or false, that overrides this 'maybe' behavior.

Really, there isn't much special to do to get this to work - all that you need to do is set IsSynchronizedWithCurrentItem to true on both the ListBox and ComboBox:
<Window x:Class="SyncSelection.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="250" Width="300" Name="This">
  <StackPanel Margin="5">
    <ComboBox ItemsSource="{Binding ElementName=This, Path=BackingCollection}" 
                    IsSynchronizedWithCurrentItem="True" 
                    Margin="0 0 0 10" />
    <ListView ItemsSource="{Binding ElementName=This, Path=BackingCollection}" 
                  Height="150" 
                  IsSynchronizedWithCurrentItem="True" />
  </StackPanel>
</Window>
 
And the C# code behind is as simple as can be (nothing special needs to be done here to get the selection synchronization to work):
public partial class Window1 : Window
{
  private ObservableCollection<string> _BackingColllection = 
      new ObservableCollection<string>();

  public Window1()
  {
    _BackingColllection.Add("Item 1");
    _BackingColllection.Add("Item 2");
    _BackingColllection.Add("Item 3");
    _BackingColllection.Add("Item 4");
    _BackingColllection.Add("Item 5");
    _BackingColllection.Add("Item 6");
    InitializeComponent();
  }

  public ObservableCollection<string> BackingCollection
  { get { return _BackingColllection; } }
}
 
You might be wondering why something like this would be useful. Well, there are two reasons this can come in handy - first, the two views could possibly be sorted differently, and it might be useful for the user to interact with both. Another possibility is that by using data templates, the two views are actually displaying different data to the user, and so it is meaningful to have the selection stay synchronized.
Labels:

Comments

Post a Comment

Popular posts from this blog

C# Snippet - Shuffling a Dictionary [Beginner]

Randomizing something can be a daunting task, especially with all the algorithms out there. However, sometimes you just need to shuffle things up, in a simple, yet effective manner. Today we are going to take a quick look at an easy and simple way to randomize a dictionary, which is most likely something that you may be using in a complex application. The tricky thing about ordering dictionaries is that...well they are not ordered to begin with. Typically they are a chaotic collection of key/value pairs. There is no first element or last element, just elements. This is why it is a little tricky to randomize them. Before we get started, we need to build a quick dictionary. For this tutorial, we will be doing an extremely simple string/int dictionary, but rest assured the steps we take can be used for any kind of dictionary you can come up with, no matter what object types you use. Dictionary < String , int > origin = new Dictionary < string , int >(); ...
1 comment
Read more

C# WPF Printing Part 2 - Pagination [Intermediate]

About two weeks ago, we had a tutorial here at SOTC on the basics of printing in WPF . It covered the standard stuff, like popping the print dialog, and what you needed to do to print visuals (both created in XAML and on the fly). But really, that's barely scratching the surface - any decent printing system in pretty much any application needs to be able to do a lot more than that. So today, we are going to take one more baby step forward into the world of printing - we are going to take a look at pagination. The main class that we will need to do pagination is the DocumentPaginator . I mentioned this class very briefly in the previous tutorial, but only in the context of the printing methods on PrintDialog , PrintVisual (which we focused on last time) and PrintDocument (which we will be focusing on today). This PrintDocument function takes a DocumentPaginator to print - and this is why we need to create one. Unfortunately, making a DocumentPaginator is not as easy as...
Post a Comment
Read more

C# WPF Tutorial - Implementing IScrollInfo [Advanced]

The ScrollViewer in WPF is pretty handy (and quite flexible) - especially when compared to what you had to work with in WinForms ( ScrollableControl ). 98% of the time, I can make the ScrollViewer do what I need it to for the given situation. Those other 2 percent, though, can get kind of hairy. Fortunately, WPF provides the IScrollInfo interface - which is what we will be talking about today. So what is IScrollInfo ? Well, it is a way to take over the logic behind scrolling, while still maintaining the look and feel of the standard ScrollViewer . Now, first off, why in the world would we want to do that? To answer that question, I'm going to take a an example from a tutorial that is over a year old now - Creating a Custom Panel Control . In that tutorial, we created our own custom WPF panel (that animated!). One of the issues with that panel though (and the WPF WrapPanel in general) is that you have to disable the horizontal scrollbar if you put the panel in a ScrollV...
Post a Comment
Read more