Dưới đây là một cái gì đó bạn có thể sử dụng Tôi đã chọn từ Jerry Nixon và Daren May tại Học viện ảo của Microsoft "Developing Universal Windows Apps with C# and XAML" và mã chứa logic DependencyObject ở đây "(W8.1-WP8.1) UNIVERSAL APP FOR MVA".
namespace App1.Behaviors
{
// <summary>
/// Helper class that allows you to monitor a property corresponding to a dependency property
/// on some object for changes and have an event raised from
/// the instance of this helper that you can handle.
/// Usage: Construct an instance, passing in the object and the name of the normal .NET property that
/// wraps a DependencyProperty, then subscribe to the PropertyChanged event on this helper instance.
/// Your subscriber will be called whenever the source DependencyProperty changes.
/// </summary>
public class DependencyPropertyChangedHelper : DependencyObject
{
/// <summary>
/// Constructor for the helper.
/// </summary>
/// <param name="source">Source object that exposes the DependencyProperty you wish to monitor.</param>
/// <param name="propertyPath">The name of the property on that object that you want to monitor.</param>
public DependencyPropertyChangedHelper(DependencyObject source, string propertyPath)
{
// Set up a binding that flows changes from the source DependencyProperty through to a DP contained by this helper
Binding binding = new Binding
{
Source = source,
Path = new PropertyPath(propertyPath)
};
BindingOperations.SetBinding(this, HelperProperty, binding);
}
/// <summary>
/// Dependency property that is used to hook property change events when an internal binding causes its value to change.
/// This is only public because the DependencyProperty syntax requires it to be, do not use this property directly in your code.
/// </summary>
public static DependencyProperty HelperProperty =
DependencyProperty.Register("Helper", typeof(object), typeof(DependencyPropertyChangedHelper), new PropertyMetadata(null, OnPropertyChanged));
/// <summary>
/// Wrapper property for a helper DependencyProperty used by this class. Only public because the DependencyProperty syntax requires it.
/// DO NOT use this property directly.
/// </summary>
public object Helper
{
get { return (object)GetValue(HelperProperty); }
set { SetValue(HelperProperty, value); }
}
// When our dependency property gets set by the binding, trigger the property changed event that the user of this helper can subscribe to
private static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var helper = (DependencyPropertyChangedHelper)d;
helper.PropertyChanged(d, e);
}
/// <summary>
/// This event will be raised whenever the source object property changes, and carries along the before and after values
/// </summary>
public event EventHandler<DependencyPropertyChangedEventArgs> PropertyChanged = delegate { };
}
}
Cách sử dụng XAML:
<TextBlock Grid.Row="0"
x:Name="WritingMenuTitle"
HorizontalAlignment="Left"
FontSize="32"
FontWeight="SemiBold"
Text="{Binding WritingMenu.Title}"
TextAlignment="Left"
TextWrapping="Wrap"/>
xaml.cs Cách sử dụng:
Behaviors.DependencyPropertyChangedHelper helper = new Behaviors.DependencyPropertyChangedHelper(this.WritingMenuTitle, Models.CommonNames.TextBlockText);
helper.PropertyChanged += viewModel.OnSenarioTextBlockTextChangedEvent;
viewmodel.cs Cách sử dụng:
public async void OnSenarioTextBlockTextChangedEvent(object sender, DependencyPropertyChangedEventArgs args)
{
StringBuilder sMsg = new StringBuilder();
try
{
Debug.WriteLine(String.Format(".....WritingMenuTitle : New ({0}), Old ({1})", args.NewValue, args.OldValue));
}
catch (Exception msg)
{
#region Exception
.....
#endregion
}
}
Hãy xem này: http://stackoverflow.com/a/2964694/2550529 – SepehrM