c# - ResourceDictionary.MergedDictionaries导致奇怪的错误

Question

在我的WPF应用程序内部，我包括另一个项目的ResourceDictionary。

<Application x:Class="namespace.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <!-- This Line causes an Error -->
                <ResourceDictionary Source="pack://application:,,,/Commons;Component/Generic.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

Metadata override and base metadata must be of the same type or derived type.

该解决方案可以成功构建并运行。

重新启动Visual Studio无法修复它。

剪切和粘贴<ResourceDictionary Source="..." />行会导致另一个错误，如注释中here所述:Value Cannot be Null. Parameter Name: item。重新启动Visual Studio将带回旧错误。

可悲的是，我还没有找到如何重现此错误的方法，我只能告诉您有关环境的更多信息:

Visual Studio 2015专业版，版本14.0.25431.01更新3

尽管我对此表示怀疑，但这些都是与我的问题有关的，这里是我安装的插件:

Resharper Ultimate 2017.1.1版

GitExtensions版本2.49.03

Answer 1

Sinatr 的评论提示我阅读有关主题的更多信息。ThemeInfo在自定义控件库内部，在ThemeInfoAttribute内部自动创建了AssemblyInfo.cs

[assembly:ThemeInfo(
 ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
                          //(used if a resource is not found in the page, 
                          // or application resource dictionaries)
 ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
                                   //(used if a resource is not found in the page, 
                                   // app, or any theme specific resource dictionaries)
)]

参量
正如它在自动生成的注释中指出的那样，第一个参数用于确定是否存在主题或特定于主题的资源字典。
第二个参数定义了是否存在通用ResourceDictionary(Generic.xaml)或在哪里找到。ResourceDictionaryLocation-枚举ResourceDictionaryLocation -Enumeration本身用于指定这些词典的位置。ResourceDictionaryLocation.None

No theme dictionaries exist.

ResourceDictionaryLocation.SourceAssembly

Theme dictionaries exist in the assembly that defines the types being themed. This expects the ResourceDictionary to be located in a /Themes-Folder. Explanation later.

ResourceDictionaryLocation.ExternalAssembly

Theme dictionaries exist in assemblies external to the one defining the types being themed.

我不会解释它是如何工作的。
为什么/Themes-文件夹
可悲的是我找不到太多的东西。如果有人有更多信息，请分享。
您是否想过，如何应用无外观控件的样式？
如果创建了一个看不见的控件，他将执行以下操作:

public class MyControl : ControlTemplate
{
    static MyControl() 
    {
        // This tells WPF to search for a Style for this type
        DefaultStyleKeyProperty.OverrideMetadata(typeof(MyControl)), 
            new FrameworkPropertyMetadata(typeof(MyControl)));
    }
}

简而言之，通过搜索Logical-Tree，然后在Application的Resources中，最后在sth中，可以找到WPF中的资源。他们叫System-Area(如果您知道更好的话，这是我的德语翻译)。
因此，取决于ThemeInfo，MyControl可能在ResourceDictionary -Folder内部的/Themes中具有其样式。 /Themes/Generic.xaml。还有，即告诉WPF将资源添加到System-Area中，最终导致自动解析适当的样式。
在/Themes/Generic.xaml内的某处:

<Style TargetType="{x:Type MyControl}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type MyControl}">
            ..
            </ControlTemplate/>
        </Setter.Value>
    </Setter>
</Style>

That's why the above ThemeInfoAttribute requires Generic.xaml to be located in a /Themes-Folder. - And somehow, even if in my case the System-Area-Functionality isn't even used for this generic file, this causes those errors. But I wasn't able to find out why.

资料来源:

ThemeInfoAttribute Constructor

ResourceDictionaryLocation Enumeration

Windows Presentation Foundation-Das Umfassende Handbuch，Rheinwerk Computing版本4