Comments on: Implementing RelativeSource binding in Silverlight

By: Luc Bos

Luc Bos — Tue, 27 Dec 2011 12:42:14 +0000

I found a memory leak in your class. You don’t remove items out of the dictionary when they are unloaded. A big PIA when switching pages.

Here is the fix:

Add a property to RelayBindingKey:

private struct RelayBindingKey
{
public DependencyProperty dependencyObject;
public FrameworkElement frameworkElement;
public FrameworkElement targetFrameworkElement;
}

Then set the targetFrameworkElement in CreateRelayBinding:

private static void CreateRelayBinding(FrameworkElement targetElement, FrameworkElement sourceElement,
BindingProperties bindingProperties)
{
…

// create a key that identifies this source binding
RelayBindingKey key = new RelayBindingKey()
{
dependencyObject = sourceDependencyProperty,
frameworkElement = sourceElement,
targetFrameworkElement = targetElement
};

…
}

Then set that on unload of the element you remove the eventhandler and the dictionary entry:

private static void OnBinding(
DependencyObject depObj, DependencyPropertyChangedEventArgs e)
{
FrameworkElement targetElement = depObj as FrameworkElement;

targetElement.Loaded += TargetElement_Loaded;
targetElement.Unloaded += TargetElement_Unloaded;
}

private static void TargetElement_Unloaded(object sender, RoutedEventArgs e)
{
FrameworkElement targetElement = sender as FrameworkElement;
if (targetElement != null)
{
targetElement.Loaded -= TargetElement_Loaded;
targetElement.Unloaded -= TargetElement_Unloaded;
}

var elementToDelete = relayBindings.Keys.FirstOrDefault(x => x.targetFrameworkElement.Equals(targetElement));
if (elementToDelete.dependencyObject != null)
{
relayBindings.Remove(elementToDelete);
Debug.WriteLine(“Element deleted”);
}
}

By: Mister Goodcat | Silverlight 5 Tidbits–Data binding

Mister Goodcat | Silverlight 5 Tidbits–Data binding — Sun, 11 Dec 2011 10:49:46 +0000

[...] way from the data context of the item back to the context of the items control, so people like Colin Eberhardt and Kiener have come up with clever ways to work around this [...]

By: José Ribeiro

José Ribeiro — Fri, 29 Jul 2011 08:19:15 +0000

Thank you very much!
It solves the problem for binding within a DataTemplate!
Not even ElementName could do that! Great!

Cheers!

By: .Net Follower

.Net Follower — Thu, 09 Jun 2011 19:43:53 +0000

In my blog I described the BoundToSelfControl, which binds itself to itself and in the same time it saves what was passed through DataContext in special field. Take a look at http://dotnetfollower.com/wordpress/2011/06/silverlight-for-windows-phone-7-how-to-bound-usercontrol-to-itself/ Thanks! .NET Follower (http://dotnetfollower.com)

By: Eivind Gussiås Løkseth

Eivind Gussiås Løkseth — Sun, 29 May 2011 11:32:20 +0000

Thanks a lot! This solved my frustrating problem!

By: Colin Eberhardt

Colin Eberhardt — Thu, 07 Apr 2011 14:31:45 +0000

Hi,

To have multiple relative source bindings you could update the code as per my multibinding solution:

http://www.scottlogic.co.uk/blog/colin/2010/08/silverlight-multibinding-updated-adding-support-for-elementname-and-twoway-binding/

To answer your second question, I like to provide working solutions to interesting problems, however I am not trying to create some all-encompassing framework of Silverlight extensions. Therefore my solutions often will not integrate together fully.

Regards, Colin E.

By: Ozz

Ozz — Thu, 07 Apr 2011 13:32:01 +0000

Has this been addressed at all? It looked like a great solution but unusable if its not production ready.

By: Javier Cobo

Javier Cobo — Thu, 07 Apr 2011 12:53:29 +0000

I’m a Silverlight newbie and I found your owesome tools googling for some solutions to my problems. At first sight your tools solve them, but then I’ve got some new ones.

I’m trying your code for relative binding and for multibinding, and I have the following questions:

1. How can I define relative binding for more than one property in a control ? ( for example, inside a listboxitem, I need to bind an Ischecked property of a control to the IsSelected property of the listboxitem, and at the same time, I need to bind the Width property of the same control to the Width of the listbox

2.- Why didn’t you implemented relative binding in multibinding – or did I miss it -?

thank uou