WPF custom DependencyProperty notify changes

Question

Hey guys

I have a class called MyComponent and it has a DependencyProperty caled BackgroundProperty.

public class MyComponent
{
    public MyBackground Background
    {
        get { return (MyBackground)GetValue(BackgroundProperty); }
        set { SetValue(BackgroundProperty, value); }
    }
    public static readonly DependencyProperty BackgroundProperty =
        DependencyProperty.Register("Background", typeof(MyBackground),
            typeof(MyComponent), new FrameworkPropertyMetadata(default(MyBackground), new PropertyChangedCallback(OnPropertyChanged)));
}

MyBackground is a class that derives from DependencyObject and it has some DependencyProperties.

public class MyBackground : DependencyObject
{
    public Color BaseColor
    {
        set { SetValue(BaseColorProperty, value); }
        get { return (Color)GetValue(BaseColorProperty); }
    }
    public static readonly DependencyProperty BaseColorProperty =
        DependencyProperty.Register("BaseColor", typeof(Color),
            typeof(MyBackground ), new UIPropertyMetadata(Colors.White));

    [...]
}

Now, what I want is when a property from MyBackground is changed, MyComponent to be notified that MyBackground has changed and the PropertyChangedCallback named OnPropertyChanged to be called.

Answer 1

Sounds like you want to use a DependencyPropertyDescriptor and AddValueChanged.

Here's an article on it: http://www.codeproject.com/Articles/34741/Change-Notification-for-Dependency-Properties.aspx

..and possibly a better implementation: http://agsmith.wordpress.com/2008/04/07/propertydescriptor-addvaluechanged-alternative/