Comment détecter une modification dans la propriété Text d'un TextBlock?

Question

Est-il possible de détecter une modification dans la propriété Text d'un élément TextBlock à l'aide d'événements?

(je suis en train de fournir une animation pour mettre en évidence les TextBlocks dont le changement propriété texte dans un DataGrid)

Answer 1

Pour autant que je peux comprendre qu'il n'y a pas un événement TextChanged dans TextBlock. En regardant votre exigence, je pense que reformater une zone de texte ne sera pas non plus une solution viable. De ma recherche préliminaire autour, this semble être une solution possible.

Answer 2

Voici un exemple similaire sur MSDN en utilisant le code-behind: http://msdn.microsoft.com/en-us/library/system.windows.data.binding.targetupdated.aspx

Answer 3

Ceci est du lien Décroché bioskope, mais simpliee.

<TextBlock Text="{Binding YourTextProperty, NotifyOnTargetUpdated=True}" 
      TargetUpdated="YourTextEventHandler"/> 

Answer 4

Bind la propriété Text à un DependencyProperty, qui a un événement déclencheur:

public static string GetTextBoxText(DependencyObject obj) 
{ 
    return (string)obj.GetValue(TextBoxTextProperty); 
} 

public static void SetTextBoxText(DependencyObject obj, string value) 
{ 
    obj.SetValue(TextBoxTextProperty, value); 
} 

public static readonly DependencyProperty TextBoxTextProperty = 
    DependencyProperty.RegisterAttached(
    "TextBoxText", 
    typeof(string), 
    typeof(TextBlockToolTipBehavior), 
    new FrameworkPropertyMetadata(string.Empty, TextBoxTextChangedCallback) 
    ); 

private static void TextBoxTextChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e) 
{ 
    TextBlock textBlock = d as TextBlock; 
    HandleTextChange(textBlock); 
} 

Dans le XAML Bind au texte TextBlock Propriété:

<TextBlock 
Text="{Binding SomeProperty, UpdateSourceTrigger=PropertyChanged}" 
    th:TextBlockBehavior.TextBoxText="{Binding Text, 
    RelativeSource={RelativeSource Self}}" /> 

Answer 5

Voici quelque chose que vous pouvez utiliser J'ai récupéré de Jerry Nixon et Daren May à la Microsoft Virtual Academy "Developing Universal Windows Apps with C# and XAML" et le code qui contient la logique DependencyObject est ici "(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 { }; 
} 
} 

Utilisation XAML:

<TextBlock Grid.Row="0" 
     x:Name="WritingMenuTitle" 
     HorizontalAlignment="Left" 
     FontSize="32" 
     FontWeight="SemiBold" 
     Text="{Binding WritingMenu.Title}" 
     TextAlignment="Left" 
     TextWrapping="Wrap"/> 

Utilisation xaml.cs:

Behaviors.DependencyPropertyChangedHelper helper = new Behaviors.DependencyPropertyChangedHelper(this.WritingMenuTitle, Models.CommonNames.TextBlockText); 
helper.PropertyChanged += viewModel.OnSenarioTextBlockTextChangedEvent; 

Utilisation viewmodel.cs:

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 
} 
} 

Answer 6

Il est plus facile que lol. Réponse tardive mais beaucoup plus simple.

// assume textBlock is your TextBlock 
DependencyPropertyDescriptor dp = DependencyPropertyDescriptor.FromProperty(TextBlock.TextProperty, typeof(TextBlock)); 

dp.AddValueChanged(textBlock, (object a, EventArgs b) => 
{ 
     MessageBox.Show("text changed"); 
});