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POCan't get DependencyProperty to work
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  1. POCan't get DependencyProperty to work
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    copied!<p>I wrote a small attached property called "IsValid" for the WPF TextBox, like so:</p> <pre><code>public enum InputTypes { Any, Integer, Double, Float } /// &lt;summary&gt; /// This attached property can be used to validate input for &lt;see cref="TextBox"/&gt;. /// &lt;/summary&gt; public class IsValid : DependencyObject { public static readonly DependencyProperty InputProperty = DependencyProperty.Register( "Input", typeof(InputTypes), typeof(IsValid), new UIPropertyMetadata(InputTypes.Any, onInput)); public static InputTypes GetInput(DependencyObject d) { return (InputTypes)d.GetValue(InputProperty); } public static void SetInput(DependencyObject d, InputTypes value) { d.SetValue(InputProperty, value); } private static void onInput(DependencyObject d, DependencyPropertyChangedEventArgs e) { var textBox = (TextBox)d; var value = (InputTypes)e.NewValue; switch (value) { case InputTypes.Any: textBox.PreviewTextInput -= validateInput; textBox.PreviewKeyDown -= validateKeyDown; break; default: textBox.PreviewTextInput += validateInput; textBox.PreviewKeyDown += validateKeyDown; break; } } private static void validateInput(object sender, TextCompositionEventArgs e) { // enforce numeric input when configured ... var textBox = (TextBox) sender; var inputTypes = (InputTypes) textBox.GetValue(InputProperty); foreach (var c in e.Text) { switch (inputTypes) { case InputTypes.Integer: if (!char.IsDigit(c)) { e.Handled = true; return; } break; case InputTypes.Double: case InputTypes.Float: if (!char.IsNumber(c)) { e.Handled = true; return; } break; default: throw new ArgumentOutOfRangeException(); } } } private static void validateKeyDown(object sender, KeyEventArgs e) { // block [SPACE] when numeric input is expected ... var textBox = (TextBox)sender; var inputTypes = (InputTypes)textBox.GetValue(InputProperty); if (inputTypes != InputTypes.Any &amp;&amp; e.Key == Key.Space) e.Handled = true; } } </code></pre> <p>End here's how I've used it:</p> <pre><code>&lt;Window x:Class="Spike.Wpf.Controls.TestApp.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:values="clr-namespace:Spike.Wpf.Controls.Input;assembly=Spike.Wpf.Controls" Title="MainWindow" Height="350" Width="525"&gt; &lt;Grid&gt; &lt;TextBox values:IsValid.Input="Double" /&gt; &lt;/Grid&gt; </code></pre> <p></p> <p>After the initialization (of the <code>DependencyProperty</code>) none of the methods in <code>IsValid</code> gets called however. What am I missing?</p>
 

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