private static void SaveMultibindingInfoForFutureAccess(MultiBindingTargetInfo multiBindingTargetInfo, MultiBinding multiBinding)
{
var frameworkElement = multiBindingTargetInfo.FrameworkElement;
RoutedEventHandler unloadedEventHandler = null;
unloadedEventHandler += (sender, args) =>
{
frameworkElement.Unloaded -= unloadedEventHandler;
MultiBindings.Remove(multiBindingTargetInfo);
};
frameworkElement.Unloaded += unloadedEventHandler;
MultiBindings[multiBindingTargetInfo] = multiBinding;
}
private static void OnMultiBindingsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var associatedObject = (FrameworkElement)d;
var multiBindings = (MultiBindingCollection)e.NewValue;
multiBindings.ForEach(multiBinding =>
{
var targetPropertyName = multiBinding.TargetProperty;
var dependencyPropertyOwnerType = multiBinding.IsBindingToAttachedProperty
? multiBinding.AttachedPropertyOwnerTypeProvider.GetType()
: associatedObject.GetType();
var targetDependencyProperty = dependencyPropertyOwnerType.ExtractDependencyProperty(targetPropertyName);
if (targetDependencyProperty == null)
{
throw new InvalidOperationException($"{targetPropertyName} is not a DependencyProperty.");
}
var multiBindingTargetInfo = new MultiBindingTargetInfo(associatedObject, targetDependencyProperty);
SaveMultibindingInfoForFutureAccess(multiBindingTargetInfo, multiBinding);
multiBinding.OnAttached(associatedObject);
});
}
internal static MultiBinding GetMultiBindingFor(FrameworkElement frameworkElement, DependencyProperty dependencyProperty)
{
var dependencyPropertyInfo = new MultiBindingTargetInfo(frameworkElement, dependencyProperty);
return(MultiBindings.ContainsKey(dependencyPropertyInfo) ? MultiBindings[dependencyPropertyInfo] : null);
}