有没有办法使用事件检测TextBlock元素的Text属性的变化?
(我正在尝试提供一个动画来突出显示在DataGrid中Text属性发生变化的TextBlock)
答案 0 :(得分:12)
这是来自bioskope答案中的链接,但是简单。
<TextBlock Text="{Binding YourTextProperty, NotifyOnTargetUpdated=True}"
TargetUpdated="YourTextEventHandler"/>
答案 1 :(得分:2)
据我所知,TextBlock中没有任何textchanged事件。看看你的要求,我觉得重新模板化文本框也不是一个可行的解决方案。从我的初步搜索中, this 似乎是一种可能的解决方案。
答案 2 :(得分:1)
将Text属性绑定到DependencyProperty,它具有事件触发器:
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);
}
在XAML中绑定到TextBlock文本属性:
<TextBlock
Text="{Binding SomeProperty, UpdateSourceTrigger=PropertyChanged}"
th:TextBlockBehavior.TextBoxText="{Binding Text,
RelativeSource={RelativeSource Self}}" />
答案 3 :(得分:0)
以下是使用代码隐藏的MSDN上的类似示例: http://msdn.microsoft.com/en-us/library/system.windows.data.binding.targetupdated.aspx
答案 4 :(得分:0)
您可以使用我从Jerry Nixon和Daren May在Microsoft Virtual Academy“Developing Universal Windows Apps with C# and XAML”中获取的内容,包含DependencyObject逻辑的代码在此处为“(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 { };
}
}
用法XAML:
<TextBlock Grid.Row="0"
x:Name="WritingMenuTitle"
HorizontalAlignment="Left"
FontSize="32"
FontWeight="SemiBold"
Text="{Binding WritingMenu.Title}"
TextAlignment="Left"
TextWrapping="Wrap"/>
用法xaml.cs:
Behaviors.DependencyPropertyChangedHelper helper = new Behaviors.DependencyPropertyChangedHelper(this.WritingMenuTitle, Models.CommonNames.TextBlockText);
helper.PropertyChanged += viewModel.OnSenarioTextBlockTextChangedEvent;
用法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
}
}