Callback when dependency property recieves xaml change

by

You would have to register a PropertyChangedCallback with property metadata.

The reason is that dependency properties set in XAML or by bindings or some other source do not invoke the CLR wrapper (the setter method). The reason is explained in the XAML Loading and Dependency Properties article on MSDN:

For implementation reasons, it is computationally less expensive to
identify a property as a dependency property and access the property
system SetValue method to set it, rather than using the property
wrapper and its setter.

…

Because the current WPF implementation of the XAML processor behavior
for property setting bypasses the wrappers entirely, you should not
put any additional logic into the set definitions of the wrapper for
your custom dependency property. If you put such logic in the set
definition, then the logic will not be executed when the property is
set in XAML rather than in code.

Your code should look like this:

public static readonly DependencyProperty IsClosedProperty =
    DependencyProperty.Register(
        "IsClosed", typeof(bool), typeof(GroupBox),
        new FrameworkPropertyMetadata(false,
            FrameworkPropertyMetadataOptions.AffectsRender,
            (o, e) => ((GroupBox)o).OnIsClosedChanged()));

public bool IsClosed
{
    get { return (bool)GetValue(IsClosedProperty); }
    set { SetValue(IsClosedProperty, value); }
}

private void OnIsClosedChanged()
{
    _rowDefContent.Height = new GridLength((IsClosed ? 0 : 1), GridUnitType.Star);
}

More Related Contents:

  1. XAML binding not working on dependency property?
  2. How do I bind a WPF DataGrid to a variable number of columns?
  3. How to pass values (parameters) between XAML pages?
  4. How to get the size of the current screen in WPF?
  5. How to bind an enum to a combobox control in WPF?
  6. How to create a WPF UserControl with NAMED content
  7. WPF: Binding a ContextMenu to an MVVM Command
  8. Listen to changes of dependency property
  9. Data Binding in WPF User Controls
  10. How to pass data from MainWindow to a User Control that’s inside the MainWindow?
  11. Can bindings create memory leaks in WPF?
  12. What’s the best way to pass event to ViewModel?
  13. How to format TimeSpan in XAML
  14. WPF Binding – Default value for empty string
  15. How to implement a navigation button in shared application resources?
  16. How to hide wpf datagrid columns depending on a property
  17. WPF TextBlock memory leak when using Font
  18. WPF: The name does not exist in the namespace [duplicate]
  19. WPF ListView: Attaching a double-click (on an item) event
  20. How to build A WPF Datagrid with an unknown number of columns
  21. The name “XYZ” does not exist in the namespace “clr-namespace:ABC”
  22. Really simple WPF form data validation – how to?
  23. Load a ResourceDictionary from an assembly
  24. WPF Filter a ListBox
  25. Interaction Triggers in Style in ResourceDictionary WPF
  26. Loading XAML XML through runtime?
  27. Stop WPF animation, storyboard begin in xaml but stopping it in codebehind?
  28. How can I use enum types in XAML?
  29. How to use nested class in WPF XAML?
  30. Binding datagrid column width

Leave a Comment