/// <summary>
/// Gets the binding source object of a binding.
/// </summary>
/// <param name="binding">The binding that indicates the source.</param>
/// <param name="serviceProvider">Service provider provided by the framework.</param>
/// <returns>The source object that is described by the binding.</returns>
protected object getBindingSource(Binding binding, IServiceProvider serviceProvider)
{
if (binding == null)
{
return(null);
}
// Optionaly get the target object:
var pvt = serviceProvider?.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
var targetObject = pvt?.TargetObject != null ? pvt.TargetObject as DependencyObject : null;
// -- Case where source is explicitely provided: --
if (binding.Source != null)
{
// Get target object as FE if provided:
if (targetObject is FrameworkElement targetAsFE)
{
// And if the binding source is the datacontext of the target object, then add
// the object the to list of datacontexts to be followed:
if (targetAsFE.IsLoaded && targetAsFE.DataContext == binding.Source)
{
if (!DataContextBindings.ContainsKey(binding))
{
DataContextBindings.Add(binding, targetAsFE);
}
return(binding.Source);
}
// Else we cannot know now ,so report assessment when target will be loaded by setting
// the current binding as 'unresolved':
else if (!targetAsFE.IsLoaded)
{
UnresolvedBindings.Add(binding, targetAsFE);
}
}
else
{
return(binding.Source);
}
}
// -- Case where element name is provided, seek source in xaml: --
else if (!string.IsNullOrWhiteSpace(binding.ElementName) && serviceProvider != null)
{
return(BindingHelpers.GetSourceFromElementName(binding.ElementName, serviceProvider));
}
// -- All other case where we have a target to provide: --
else if (targetObject != null)
{
return(getBindingSource(binding, targetObject)); // call the other method without service provider.
}
return(null);
}
/// <summary>
/// Executed when the targeted framework element is loaded.
/// </summary>
/// <param name="sender">The framework element that sent the event.</param>
/// <param name="e">Information about the loaded event.</param>
private void Unresolvedtarget_Loaded(object sender, RoutedEventArgs e)
{
if (sender is FrameworkElement casted)
{
casted.Loaded -= Unresolvedtarget_Loaded; // unsubscribe.
// Applies only if extension is still alive:
if (IsExtensionValid)
{
// Check for each unresolved binding:
foreach (var item in Bindings)
{
// If they lie in the unresolved list, and the FE that sent the event is registered for that purpose:
if (item is Binding binding && UnresolvedBindings.ContainsKey(binding) && UnresolvedBindings[binding] == casted)
{
// Get source (should be ok now that visual tree is constructed):
if (getBindingSourcePropertyValue(item as Binding, casted) is INotifyCollectionChanged collection)
{
CollectionChangedEventManager.AddListener(collection, this); // add this as listener to update collection when it changes
}
}
}
// Get the opportunity to register to datacontext change event
// in case we just processed a value that was unresolved and now marked in the
// list of the datacontext bindings to follow:
if (DataContextBindings.ContainsValue(casted))
{
foreach (Binding binding in Bindings)
{
if (UnresolvedBindings.ContainsKey(binding)) // was unresolved
{
if (DataContextBindings[binding] == casted) // and is in the datacontext list to follow
{
casted.DataContextChanged += DatacontextTarget_DataContextChanged;
}
}
}
}
// Since resolved, remove all related unresolved
// bindings for the current framework element:
foreach (Binding binding in Bindings)
{
if (UnresolvedBindings.ContainsKey(binding) && UnresolvedBindings[binding] == casted)
{
UnresolvedBindings.Remove(binding);
}
}
}
}
}
/// <summary>
/// Gets the binding source object of a binding.
/// </summary>
/// <param name="binding">The binding that indicates the source.</param>
/// <param name="target">A target object where the source might be found.</param>
/// <returns>The source object that is described by the binding.</returns>
protected object getBindingSource(Binding binding, DependencyObject target)
{
if (binding == null)
{
return(null);
}
var targetAsFE = target as FrameworkElement;
// -- Case where source is explicitely provided: --
if (binding.Source != null)
{
// If a target object is provided:
if (targetAsFE != null)
{
// And if the binding source is the datacontext of the target object, then add
// the object the to list of datacontexts to be followed:
if (targetAsFE.IsLoaded && targetAsFE.DataContext == binding.Source)
{
if (!DataContextBindings.ContainsKey(binding))
{
DataContextBindings.Add(binding, targetAsFE);
}
return(binding.Source);
}
// Else we cannot know now so report assessment at target loading:
else if (!targetAsFE.IsLoaded)
{
UnresolvedBindings.Add(binding, targetAsFE);
}
}
else
{
return(binding.Source);
}
}
// -- In other cases that depends on datacontext or visual tree --
else if (target != null)
{
// -- Case where relative source is provided: --
if (binding.RelativeSource != null)
{
var relative = BindingHelpers.GetSourceFromRelativeSource(binding.RelativeSource, target);
if (relative == null && targetAsFE != null && !targetAsFE.IsLoaded)
{
if (!UnresolvedBindings.ContainsKey(binding))
{
UnresolvedBindings.Add(binding, targetAsFE);
}
}
}
// -- Case where no source is given at all: --
else if (binding.Source == null && binding.RelativeSource == null &&
string.IsNullOrWhiteSpace(binding.ElementName) && targetAsFE != null)
{
if (targetAsFE.IsLoaded)
{
if (!DataContextBindings.ContainsKey(binding))
{
DataContextBindings.Add(binding, targetAsFE);
}
return(targetAsFE.DataContext);
}
else if (!UnresolvedBindings.ContainsKey(binding))
{
UnresolvedBindings.Add(binding, targetAsFE);
}
}
}
return(null);
}
