WPF 高级篇 MVVM 附加属性

原文:WPF 高级篇 MVVM 附加属性

WPF 特性之一 附加属性 在本文里实现文本框内容的验证

public  class TextBoxHelper:DependencyObject
{

public static bool GetisOnlyNumber(DependencyObject obj)
{
return (bool)obj.GetValue(isOnlyNumberProperty);
}

public static void SetisOnlyNumber(DependencyObject obj, bool value)
{
obj.SetValue(isOnlyNumberProperty, value);
}

// Using a DependencyProperty as the backing store for isOnlyNumber.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty isOnlyNumberProperty =
DependencyProperty.RegisterAttached("isOnlyNumber", typeof(bool), typeof(TextBoxHelper), new PropertyMetadata(false,OnIsOnlyNumberChange));

private static void OnIsOnlyNumberChange(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var text = d as TextBox;
if ((bool)e.NewValue) 
{
text.PreviewTextInput += text_PreviewTextInput;
}else{
text.PreviewTextInput -= text_PreviewTextInput;
}
}

static void text_PreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
{
e.Handled = IsNotNumber(e.Text);
}

private static bool IsNotNumber(string content) 
{
Regex regex = new Regex("[^0-9]");
return regex.IsMatch(content);
}


}

引用命名空间

  xmlns:bhx ="clr-namespace:WPF.Behaviors"

        <TextBox bhx:TextBoxHelper.isOnlyNumber="True" HorizontalAlignment="Left" Height="23" Margin="10,131,0,0" TextWrapping="Wrap" Text="{Binding CurrentBook.Pages}" VerticalAlignment="Top" Width="120"/>

原文地址：https://www.cnblogs.com/lonelyxmas/p/12075813.html