defining-wpf-dependencyproperty

Register a static readonly DependencyProperty using DependencyProperty.Register with the property name, type, owner type, and PropertyMetadata, then expose it through a CLR wrapper that calls GetValue and SetValue. This enables data binding, styling, and animation support.

Pass both callbacks through FrameworkPropertyMetadata when registering the property. Validation runs first via ValidateValueCallback, then CoerceValueCallback can modify the value, and finally PropertyChangedCallback handles the applied change.

A DependencyProperty is registered on the owning control type with a CLR wrapper, while an attached property is registered via RegisterAttached on a static class with static Get and Set methods. Attached properties can be set on any DependencyObject in XAML.

The default value must be set through PropertyMetadata during registration, not by assigning the CLR wrapper in the constructor. Setting the wrapper creates a local value that overrides the metadata default and can break style triggers.

Use DependencyProperty on visual elements like custom controls where you need styling, animation, and property value inheritance. Use INotifyPropertyChanged in ViewModels and plain data classes that are not DependencyObjects.