只读依赖项属性更新,但在首次使用时不起作用

我正试图创建一些WPF用户控件,将其包含在库中,以便与我的团队共享,但只读属性对我的工作方式有一些问题。

对于这个问题,我制作了一个具有两个DependencyProperties的非常简单的用户控件。一种基于 enum 另一个根据所选参数执行操作 枚举 . 这个 枚举 用于选择按钮将使用的样式。

该应用程序是一个常规Wpf应用程序,有一个Wpf用户控件库作为参考。我怀疑控制库 可以 是问题的原因,所以我觉得它与示例相关。

Wpf控制库1

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:WpfControlLibrary1">
    <Style x:Key="SampleStyle-Font1">
        <Setter Property="TextElement.FontFamily" Value="Wingdings" />
        <Setter Property="TextElement.FontSize" Value="30" />
    </Style>
    <Style x:Key="SampleStyle-Font2">
        <Setter Property="TextElement.FontFamily" Value="Elephant" />
        <Setter Property="TextElement.FontSize" Value="30" />
    </Style>
    <Style x:Key="SampleStyle-Font3">
        <Setter Property="TextElement.FontFamily" Value="Times New Roman" />
        <Setter Property="TextElement.FontSize" Value="30" />
    </Style>
</ResourceDictionary>

UserControl1.xaml:

<UserControl x:Class="WpfControlLibrary1.UserControl1"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
            xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
            xmlns:local="clr-namespace:WpfControlLibrary1"
            mc:Ignorable="d"
            d:DesignHeight="100" d:DesignWidth="200">
    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Dictionary1.xaml"></ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <UserControl.Template>
        <ControlTemplate>
            <Button Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:UserControl1}}, Path=Command}">
                <StackPanel>
                    <Label Style="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:UserControl1}}, Path=ReadOnlyStyle}" Content="{Binding Path=Content, RelativeSource={x:Static RelativeSource.TemplatedParent}}"></Label>
                </StackPanel>
            </Button>
        </ControlTemplate>
    </UserControl.Template>
</UserControl>

UserControl1.xaml.cs

namespace WpfControlLibrary1 {
    using System.Windows;
    using System.Windows.Controls;

    /// <summary>
    /// Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl {
        public enum StyleSelector {
            Style1,
            Style2,
            Style3
        }

        public static DependencyProperty SelectedStyleProperty =
            DependencyProperty.Register("SelectedStyle", typeof(StyleSelector), typeof(UserControl1), new PropertyMetadata(ReadOnlyStyle_Changed));

        private static readonly DependencyPropertyKey ReadOnlyStylePropertyKey =
            DependencyProperty.RegisterReadOnly("ReadOnlyStyle", typeof(Style),
                typeof(UserControl1), null);

        public UserControl1() {
            InitializeComponent();
        }

        public StyleSelector SelectedStyle {
            get => (StyleSelector)GetValue(SelectedStyleProperty);
            set => SetValue(SelectedStyleProperty, value);
        }

        public Style ReadOnlyStyle => (Style)GetValue(ReadOnlyStylePropertyKey.DependencyProperty);

        private static void ReadOnlyStyle_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e) {
            if (!(d is UserControl1 userControl1)) {
                return;
            }

            Style style;
            switch (userControl1.SelectedStyle) {
                case StyleSelector.Style1:
                    style = (Style)userControl1.FindResource("SampleStyle-Font1");
                    break;
                case StyleSelector.Style2:
                    style = (Style)userControl1.FindResource("SampleStyle-Font2");
                    break;
                case StyleSelector.Style3:
                    style = (Style)userControl1.FindResource("SampleStyle-Font3");
                    break;
                default:
                    style = (Style)userControl1.FindResource("SampleStyle-Font1");
                    break;
            }

            userControl1.SetValue(ReadOnlyStylePropertyKey, style);
        }
    }
}

Wpf应用程序

MainWindow.xaml:

<Window x:Class="ReadOnlyDependencyPropertiesWithUserControls.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:ReadOnlyDependencyPropertiesWithUserControls"
        xmlns:wpfControlLibrary1="clr-namespace:WpfControlLibrary1;assembly=WpfControlLibrary1"
        mc:Ignorable="d"
        Title="Example" Height="200" Width="400">
    <StackPanel>
        <wpfControlLibrary1:UserControl1 SelectedStyle="Style1" Content="This is the first control"></wpfControlLibrary1:UserControl1>
        <wpfControlLibrary1:UserControl1 SelectedStyle="Style2" Content="This is the second control"></wpfControlLibrary1:UserControl1>
        <wpfControlLibrary1:UserControl1 SelectedStyle="Style3" Content="This is the third control"></wpfControlLibrary1:UserControl1>
    </StackPanel>
</Window>

下面的输出显示第一个控件没有 不 展示 Style . 如果我运行应用程序,使用Live编辑器将其切换到Style2,然后返回Style1,WingDings字体确实会接管,但在新运行时不会。这看起来确实像是一个依赖属性问题,但据我所知,我的设置是正确的,特别是因为其他两个控件似乎都可以工作。