wpf - Default(Theme) style and its DefaultStyleKey

WPF样式查找机制解析

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本文探讨了WPF中DefaultStyleKey属性的作用及其在样式查找中的应用。通过反射获取DefaultStyleKey属性值，并展示了如何利用该属性为控件查找对应的主题样式。

As dicsused in the subsection of Default (theme) style from the topic of Dependency Property Value Precedence we know that the theme style use the type as the key for controls; But when theme is applied to a given Element instanfe, themes lookup for the particule type is performed by checking the DefaultStyleKey;

from DefaultStyleKey, we know that it is a protected internal property, out of curious we want to find out what is the value of the DefaultStyleKey;

Below is the code that I used for the look up .

To reflection get a property

    public static object ReflectionGetProperty(object obj, Type type , string propertyName, BindingFlags[] bindingFlags)
    {
      if (string.IsNullOrEmpty(propertyName)) throw new ArgumentException("propertyName");
      if (bindingFlags == null) throw new ArgumentNullException("bindingFlags");
      if (type == null) throw new ArgumentNullException("type");
      if (bindingFlags.Length == 0) throw new ArgumentException("bindingFlags");


      var binding = bindingFlags[0];
      for (int i = 0; i < bindingFlags.Length; i++)
      {
        binding |= bindingFlags[i];
      }
      var prop = type.GetProperty(propertyName, binding);
      if (prop != null)
      {
        return prop.GetValue(obj, null);
      }
      return null;
    }

To use the ReflectionGetProperty method to get the Value of "DefaultStyleKey"

    public static object ReflectionGetDefaultStyle(FrameworkElement frameworkElement)
    {
      if (frameworkElement == null) throw new ArgumentNullException("frameworkElement");
      object defaultStyleKey = ReflectionGetProperty(frameworkElement, typeof(FrameworkElement), "DefaultStyleKey", new BindingFlags[] { BindingFlags.NonPublic | BindingFlags.Instance });
      if (defaultStyleKey != null)
      {
        var style = frameworkElement.TryFindResource(defaultStyleKey);
        return style;
      }
      return null;
    }

and suppose visual is an FrameworkElement, this is how you get Default Style.

FrameworkElement visual = ...
var style = ReflectionGetDefaultStyle(visual);

If you inspect the value of DefaultStyleKey in the method, you will see that the value of the DefautlstyleKey as in the method ReflectionGetDefaultKey is

? defaultStyleKey
{Name = "TextBlock" FullName = "System.Windows.Controls.TextBlock"}
    base {System.Type}: {Name = "TextBlock" FullName = "System.Windows.Controls.TextBlock"}
    Assembly: {PresentationFramework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35}
...

As you can see that it is just the Type of textBlock (our Visual is a TextBlock);

It does not have some pratical siginificance, but some explore that is interesting.