在类型 "ResourceDictionary" 中找不到可附加的 属性 "ThemeDictionaries"

The attachable property "ThemeDictionaries" was not found in type "ResourceDictionary"

以下代码在 app.xaml Windows Phone 8 应用程序中。它收到错误 The attachable property "ThemeDictionaries" was not found in type "ResourceDictionary"。同样,它不设置背景。我正在尝试在整个应用程序中设置背景,并可以选择使用 (App.Current.Resources["BackgroundImage"] as ImageBrush).ImageSource = imgSrc; 通过 c# 代码更改它。

<Application
    x:Class="MyApp.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone">  
     <Application.Resources>
          <ResourceDictionary>
           <ResourceDictionary.ThemeDictionaries>
              <ResourceDictionary x:Key="Default">
                    <ImageBrush x:Key="BackgroundImage" ImageSource="Assets/BackgroundDefault.jpg" Stretch="UniformToFill" />
              </ResourceDictionary>
              <ResourceDictionary x:Key="Dark">
                    <ImageBrush x:Key="BackgroundImage" ImageSource="Assets/BackgroundDark.jpg" Stretch="UniformToFill" />
              </ResourceDictionary>
           </ResourceDictionary.ThemeDictionaries>
            <local:LocalizedStrings xmlns:local="clr-namespace:MyApp" x:Key="LocalizedStrings"/>
            <DataTemplate x:Key="SmallPanoramaTitle">
                <ContentPresenter>
                    <TextBlock Text="{Binding}" FontSize="25" Margin="0,30,0,0" />
                </ContentPresenter>
            </DataTemplate>
        </ResourceDictionary>
      </Application.Resources>
      <Application.ApplicationLifetimeObjects>
        <!--Required object that handles lifetime events for the application-->
        <shell:PhoneApplicationService
            Launching="Application_Launching" Closing="Application_Closing"
            Activated="Application_Activated" Deactivated="Application_Deactivated"/>
       </Application.ApplicationLifetimeObjects>
</Application>

ResourceDictionary.ThemeDictionaries 在 windows phone silverlight 应用程序中不可用。

您也可以使用 ThemeManager library to mange your themes in WP silverlight. This is an excellent library and its available in nuget

请参阅 this 页面以了解如何使用 ThemeManager 。您还可以加载自定义主题文件