隐藏控件时隐藏验证装饰

Question

在WPF中,如何在隐藏控件时隐藏验证错误模板装饰(默认情况下为红色框)？当我隐藏我的控件(以便于在视图之间切换)时,错误装饰会一直存在.

更难的是,我如何使用MVVM做到这一点？

Answer 1

有一个的默认值ControlTemplate,其中有一个引用它.看起来像这样Validation.ErrorTemplateAdornedElementPlaceholderAdornedElement

<ControlTemplate>
    <Border BorderBrush="Red" BorderThickness="1">
        <AdornedElementPlaceholder />
    </Border>
</ControlTemplate>

从这里可以将的可见性绑定Border到的可见性AdornedElementPlaceholder.AdornedElement,从而将其可见性.然后我们让所有Control有这个问题的人使用它Validation.ErrorTemplate而不是默认的.这是一个例子

XAML

<Window.Resources>
    <ControlTemplate x:Key="ValidationErrorTamplate">
        <Border Visibility="{Binding ElementName=placeHolder,
                                     Path=AdornedElement.Visibility}"
                BorderBrush="Red"
                BorderThickness="1">
            <AdornedElementPlaceholder x:Name="placeHolder"/>
        </Border>
    </ControlTemplate>
</Window.Resources>
<TextBox ...
         Validation.ErrorTemplate="{StaticResource ValidationErrorTamplate}">

更新
要引用UserControl绑定中的父级,您可以

1.对于特定控件,您可以使用Parent属性向上走逻辑树

示例:如果TextBox位于a StackPanel中,UserControl我们可以使用Parent.Parent引用它

<UserControl ...>
    <StackPanel>
        <TextBox ...
                 Validation.ErrorTemplate="{StaticResource ValidationErrorTamplate2}">

<ControlTemplate x:Key="ValidationErrorTamplate2">
    <Border Visibility="{Binding ElementName=placeHolder,
                                 Path=AdornedElement.Parent.Parent.Visibility}"
            BorderBrush="Red"
            BorderThickness="1">
        <AdornedElementPlaceholder x:Name="placeHolder"/>
    </Border>
</ControlTemplate>

2.对于一个更动态的方法,你可以使用一个ResourceDictionary代码隐藏文件,你可以在其中使用Loaded事件Border.在其中,您沿着可视​​树向上查找父级UserControl并将其用作绑定的源

ValidationErrorTemplateDictionary.xaml

<ResourceDictionary x:Class="ValidationErrorVisibility.ValidationErrorTemplateDictionary"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <ControlTemplate x:Key="ValidationErrorTamplate3">
        <Border BorderBrush="Red"
                BorderThickness="1"
                Loaded="ValidationAdorner_Loaded">
            <AdornedElementPlaceholder/>
        </Border>
    </ControlTemplate>
</ResourceDictionary>

ValidationErrorTemplateDictionary.xaml.cs

public partial class ValidationErrorTemplateDictionary
{
    private void ValidationAdorner_Loaded(object sender, RoutedEventArgs e)
    {
        Border adornedBorder = sender as Border;
        Binding visibilityBinding = new Binding("Visibility");
        UIElement adornedElement = ((AdornedElementPlaceholder)adornedBorder.Child).AdornedElement;
        UserControl parentUserControl = GetVisualParent<UserControl>(adornedElement);
        visibilityBinding.Source = parentUserControl;
        adornedBorder.SetBinding(Border.VisibilityProperty, visibilityBinding);
    }

    public static T GetVisualParent<T>(object childObject) where T : Visual
    {
        DependencyObject child = childObject as DependencyObject;
        while ((child != null) && !(child is T))
        {
            child = VisualTreeHelper.GetParent(child);
        }
        return child as T;
    }
}

你的UserControl

<UserControl ...>
    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="ValidationErrorTemplateDictionary.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <StackPanel>
        <TextBox ...
                 Validation.ErrorTemplate="{StaticResource ValidationErrorTamplate3}">