为什么DefaultStyleKey不更改子类的默认样式？ [英] Why doesn't DefaultStyleKey change the default style for my subclasses?

问题描述

我有一个名为 Handle 的基类，从中可以导出几个基类，例如 RectHandle 和 EllipseHandle 。在那些子类中，我尝试覆盖默认样式键以指向 Handle ，但未应用定位到 Handle 的样式。 。我仍然必须直接或通过 BasedOn样式明确指定 RectHandle 或 EllipseHandle 的目标。我缺少什么？

I have a base class called Handle from which I derive several base classes such as RectHandle and EllipseHandle. In those subclasses I have attempted to override the default style key to point to Handle but a style targeting Handle is not applied. I still have to explicitly target RectHandle or EllipseHandle either directly, or via a 'BasedOn' style. What am I missing?

以下是DefaultStyleKeyProperty的MSDN摘录：

Here's the MSDN excerpt for DefaultStyleKeyProperty:

A控件通常会将此属性的默认值覆盖为其自己的类型，但是在某些情况下，也可以使用主题字典中存在其样式的基本类型。

A control typically overrides the default value of this property to be its own type, but in some cases could also use a base type for which a style in the theme dictionaries exists.

这是我的代码

public abstract class Handle : Shape
{
    static Handle()
    {
        WidthProperty.OverrideMetadata(
            typeof(Handle),
            new FrameworkPropertyMetadata(10.0));

        HeightProperty.OverrideMetadata(
            typeof(Handle),
            new FrameworkPropertyMetadata(10.0));

        FillProperty.OverrideMetadata(
            typeof(Handle),
            new FrameworkPropertyMetadata(Brushes.Yellow));

        StrokeProperty.OverrideMetadata(
            typeof(Handle),
            new FrameworkPropertyMetadata(Brushes.Gray));

        StrokeThicknessProperty.OverrideMetadata(
            typeof(Handle),
            new FrameworkPropertyMetadata(2.0));
    }
}

public class RectHandle : Handle
{
    static RectHandle()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(RectHandle),
            new FrameworkPropertyMetadata(typeof(Handle)));
    }

    protected override Geometry DefiningGeometry
    {
        get
        {
            var origin = new Point(-RenderSize.Width / 2, -RenderSize.Height / 2);
            var rect = new Rect(origin, RenderSize);
            return new RectangleGeometry(rect);
        }
    }
}

public class EllipseHandle : Handle
{
    static RectHandle()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(EllipseHandle),
            new FrameworkPropertyMetadata(typeof(Handle)));
    }

    protected override Geometry DefiningGeometry
    {
        get
        {
            var origin = new Point(-RenderSize.Width / 2, -RenderSize.Height / 2);
            var rect = new Rect(origin, RenderSize);
            return new EllipseGeometry(rect);
        }
    }
}

还有样式...

<Style TargetType="{x:Type annotations:Handle}">
    <Setter Property="Stroke" Value="Red" />
</Style>

同样，这不起作用。

我的解决方法是根据第一种创建其他两种样式，但是我认为这是 DefaultStyleKey 属性。

My work-around is to create two other styles based on the first, but I thought that was the entire point of the DefaultStyleKey property.

<Style TargetType="{x:Type annotations:Handle}">
    <Setter Property="Stroke" Value="Red" />
</Style>

<Style TargetType="{x:Type annotations:RectHandle}"
    BasedOn="{StaticResource {x:Type annotations:Handle}}" />

<Style TargetType="{x:Type annotations:EllipseHandle}"
    BasedOn="{StaticResource {x:Type annotations:Handle}}" />

推荐答案

我知道了。 DefaultStyleKey 属性 仅引用在主题 或 Generic.xaml中定义的样式。 在主题下。如果我将 Handle 样式移到那里，突然间，它就会起作用。相反，如果我将其复制到本地窗口中（已完成），则不会。有趣的是查找方式不同。

I figured it out. The DefaultStyleKey property only refers to styles defined in a theme, or in Generic.xaml under Themes. If I move my Handle style there, all of a sudden, it works. If I instead copy it local to the window, which I had done, it doesn't. Interesting that the lookups are different.

这篇关于为什么DefaultStyleKey不更改子类的默认样式？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！