隐藏控件时隐藏验证装饰 [英] Hiding validation adornment when hiding a control

问题描述

在WPF中，如何隐藏控件时如何隐藏验证错误模板装饰（默认为红色框）？当我隐藏控件（以方便在视图之间切换）时，错误装饰仍然存在。

How, in WPF, do you hide the validation error template adornment (red box by default) when you hide a control? When I hide my controls (to facilitate switching between views) the error adornment sticks around.

更困难的是，如何使用MVVM做到这一点？

Even more difficult, how do I do this using MVVM?

推荐答案

Validation.ErrorTemplate ControlTemplate c $ c>具有 AdornedElementPlaceholder ，而该引用又引用了其 AdornedElement 。看起来像这样

The default ControlTemplate for the Validation.ErrorTemplate has an AdornedElementPlaceholder which in turn has a reference to its AdornedElement. It looks like this

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

从这里可以绑定 Border 到 AdornedElementPlaceholder.AdornedElement 的可见性以链接其可见性。然后，使所有出现此问题的 Control 都使用此 Validation.ErrorTemplate 而不是默认值。这是一个示例

From here would could bind the Visibility of the Border to the Visibility of the AdornedElementPlaceholder.AdornedElement to link their Visibility. Then we make all the Control's that has this problem use this Validation.ErrorTemplate instead of the default one. Here's an example

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

引用父级 UserControl 在绑定中您可以

1。对于特定控件，您可以使用父项属性

1.For a specific control you can walk up the logical tree using the Parent Property

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

Example: If the TextBox is located in a StackPanel in the UserControl we can reference it with Parent.Parent

<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。要获得更动态的方法，可以使用 ResourceDictionary ，并在文件后面添加代码，您可以在其中使用 Border 的Loaded事件。在其中，您可以走到可视树上，找到父 UserControl 并将其用作绑定的源

2.For a more dynamic approach you can use a ResourceDictionary with a code behind file where you make use of the Loaded event for the Border. In it, you walk up the visual tree to find the parent UserControl and use that as the source for the Binding

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;
    }
}

您的UserControl

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

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