Silverlight / WPF中的Control和ContentControl有什么区别？

Question

Please explain the actual differences between Control and ContentControl because googling didn't yielded good results.

Actually, I'm facing one issue related to this: I have a Autocompletebox control ( inheriting from ContentControl ). For a new value entered by user, the corresponding Property's Mode=TwoWay is working fine and Property's value is getting updated in ViewModel and same repeats if the user enters another new value. But if a previously entered value is again entered by the user then the Property's value is not being updated.

So I guess that may be this Autocompletebox control should inherit from Control class rather than ContentControl .

Am I correct?, please add your inputs and feedbacks.

EDIT - Adding pseudo code::

Control class:-

public class MyAutoBox : ContentControl
{
    public int MyProp
    {
        get { return (int)GetValue(MyPropProperty); }
        set { SetValue(MyPropProperty, value); }
    }

    public static readonly DependencyProperty MyPropProperty =
      DependencyProperty.Register("MyProp", typeof(int), typeof(MyAutoBox), new PropertyMetadata(0));

}

ViewModel:-

public class MyViewModel : ViewModelBase, INavigationAware
{
    private int MyProp;

    public int MyProp
    {
        get { return MyProp; }
        set
        {
            if (MyProp != value)
            {
                MyProp = value;
                RaisePropertyChanged(() => MyProp);
            }
        }
    }

}

Xaml:

<MyControls:MyAutoBox Grid.Row="1"
                    Grid.Column="0"
                    Margin="10,0"
                    CanTypeIn="True"
                    MyProp="{Binding MyProp,  Converter={StaticResource NullToNumericConverter},Mode=TwoWay}"
<MyControls/>  

Thanks.

Answer 1

ContentControl is actually inherited from Control class. So the issue does not appear due to that. Property Changed mechanism will work, when a property value really changed. If the new value and old value are equal, there is no need to update the ViewModel.

Apart from that, Control class is the base class for most of the UI Elements in WPF. It holds the properties like Background, Foreground, Font, etc.

ContentControl is a class which represents an element, that can accept single item as child. For example, ListBoxItem, ComboBoxItem, etc are ContentControls.