45 lines
1.1 KiB
C#
45 lines
1.1 KiB
C#
using System.Windows;
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using System.Windows.Controls;
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using Microsoft.Xaml.Behaviors;
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namespace ShrlAlgoToolkit.Mvvm.Behaviors;
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/// <summary>
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/// 在xaml的资源中声明，viewModel继承IValidationExceptionHandler，通过IsValid判断能否执行
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/// </summary>
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public class ValidationRuleBehavior : Behavior<FrameworkElement>
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{
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private int errorCount;
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protected override void OnAttached()
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{
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base.OnAttached();
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AssociatedObject.AddHandler(Validation.ErrorEvent, new EventHandler<ValidationErrorEventArgs>(OnValidationError));
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}
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protected override void OnDetaching()
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{
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AssociatedObject.RemoveHandler(Validation.ErrorEvent, new EventHandler<ValidationErrorEventArgs>(OnValidationError));
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}
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private void OnValidationError(object sender, ValidationErrorEventArgs e)
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{
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if (AssociatedObject.DataContext is IValidationExceptionHandler handler)
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{
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if (e.OriginalSource is UIElement elem)
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{
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if (e.Action == ValidationErrorEventAction.Added)
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{
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errorCount++;
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}
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else if (e.Action == ValidationErrorEventAction.Removed)
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{
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errorCount--;
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}
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}
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handler.IsValid = errorCount == 0;
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}
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}
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}
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