WPF ValidationRule的特点（默认目标-源才校验）

默认是当目标发生改变时候，通过绑定改变源时候进行校验，因为WPF认为源是安全的，如果想让源改变时候，也进行校验则设置验证规则的ValidatesOnTargetUpdated =true

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace XamlTest
{
/// <summary>
/// Interaction logic for Window16.xaml
/// </summary>
public partial class Window16 : Window
{
public Window16()
{
InitializeComponent();
Binding b = new Binding();
b.Source= slider;
b.Path = new PropertyPath("Value");
b.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
RangeValidationRule vr = new RangeValidationRule();
//vr.ValidatesOnTargetUpdated =true;
b.NotifyOnValidationError = true;
b.ValidationRules.Add(vr);
txt.SetBinding(TextBox.TextProperty, b);
txt.AddHandler(Validation.ErrorEvent,new RoutedEventHandler(this.ValidationError));
}

private void ValidationError(object sender, RoutedEventArgs e)
{
if (Validation.GetErrors(txt).Count>0)
{
txt.ToolTip = Validation.GetErrors(txt)[0].ErrorContent.ToString();
}
}
}
}

巴特西

WPF ValidationRule的特点（默认目标-源才校验）

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