What are the scenarios in which we need to use dependency property in WPF?

Question

We can achieve the binding by simply CLR property, so why do we need to use DP?

Answer 1

When do you need DPs over CLRPs?

• When you need binding
• when you need property value change callback (Default Implementation)
• When you need property value validation
• When you need animation
• When you need property value inheritance
• When you need to attach a property value to another element (Attached Property, but still)
• When you need styling

Some of these can be implemented in CLR properties. But, with DPs, its piece of cake.

Answer 2

Typically these are declared in UserControls and derived controls.

You can bind to a CLR property, but you can't bind with a CLR property; you'll need a dependency property to do any binding.

Edit (in response to comment)

Let's say you need a TextBox, but you want to customize it to have different behaviour in "EditMode" and "ReadMode". You'll need to either create a derived class or a UserControl; in either case you'll add a DependencyPropery.

public class TextBoxWithModes : TextBox
{
    public bool EditMode
    {
        get { return (bool) GetValue(EditModeProperty); }
        set { SetValue(EditModeProperty, value); }
    }

    public static readonly DependencyProperty EditModeProperty = DependencyProperty.Register(
        "EditMode", typeof (bool), typeof (TextBoxWithModes));
}

With this in place, you can declare it in XAML:

<Namespace:TextBoxWithModes Text="enter text here"
    Width="200"
    HorizontalAlignment="Center"
    EditMode="{Binding IsChecked, ElementName=editModeCheckBox}" />