/// <summary>
/// Handle the Loaded event of the element to which this view model is attached
/// inorder to enable the attached
/// view model to bind to properties of the parent element
/// </summary>
static void Element_Loaded(object sender, RoutedEventArgs e)
{
FrameworkElement targetElement = sender as FrameworkElement;
FrameworkElement parent = targetElement.Parent as FrameworkElement;
// use the attached view model as the DataContext of the element it is attached to
AttachedViewModelBase attachedModel = GetAttach(targetElement);
targetElement.DataContext = attachedModel;
// find the ProgressBar and associated it with the view model
var progressBar = targetElement.Ancestors <ProgressBar>().Single() as ProgressBar;
attachedModel.SetProgressBar(progressBar);
// bind the DataContext of the view model to the DataContext of the parent.
attachedModel.SetBinding(AttachedViewModelBase.DataContextProperty,
new Binding("DataContext")
{
Source = parent
});
// bind the piggyback to give DataContext change notification
attachedModel.SetBinding(AttachedViewModelBase.DataContextPiggyBackProperty,
new Binding("DataContext")
{
Source = parent
});
}
/// <summary>
/// Change handler for the Attach property
/// </summary>
private static void OnAttachChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
FrameworkElement targetElement = d as FrameworkElement;
AttachedViewModelBase viewModel = e.NewValue as AttachedViewModelBase;
viewModel.AttachedElement = targetElement;
// handle the loaded event
targetElement.Loaded += new RoutedEventHandler(Element_Loaded);
}
/// <summary>
/// Handles changes to the DataContextPiggyBack property.
/// </summary>
private static void OnDataContextPiggyBackChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
AttachedViewModelBase viewModel = d as AttachedViewModelBase;
viewModel.OnDataContextChanged();
}
public static void SetAttach(DependencyObject d, AttachedViewModelBase value)
{
d.SetValue(AttachProperty, value);
}
public static void SetAttach(DependencyObject d, AttachedViewModelBase value)
{
d.SetValue(AttachProperty, value);
}