WPF 如何给多个资源字典相同的 class？

Question

I'm not sure if I'm asking the right type of question, but here's my issue.

I have multiple resource dictionaries, and I would like to allow for users to customise these resource dictionaries to create their own styles. There are styles built in , and styles loaded from files, each style has a single resource dictionary with a specified class .

I wanted to keep the styles separate so they could be customised, but I need some event handlers, so I made a generic event handler class ResourceDictionaryEventHandler.cs .

The issue now is when I assign more than one resource dictionary the same class, I get this error . The app.xaml had some of the styles already loaded, but even after only loading one set of styles I still got the same error.

Its weird too because it seemed to be working earlier, but simply restarting Visual Studio the issue surfaced.

This image does have 2 resource dictionaries per style, but only one have them has been assigned a class.

So how do I assign this EventHandler class to multiple resource dictionaries? Or is there a better way of doing it?

Answer 1

I made a small example for you. I have added two resource dictionaries named Dark.xaml and Light.xaml to the project.

I have defined the colors that I will use in these resource dictionaries.

Dark.xaml Code

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:ThemeExample">
<ResourceDictionary.MergedDictionaries>
    <ResourceDictionary>
        <SolidColorBrush x:Key="ColorMode" Color="DarkBlue"/>
    </ResourceDictionary>
</ResourceDictionary.MergedDictionaries>

Light.xaml code

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:ThemeExample">

<ResourceDictionary.MergedDictionaries>
    <ResourceDictionary>
        <SolidColorBrush x:Key="ColorMode" Color="LightBlue"/>
    </ResourceDictionary>
</ResourceDictionary.MergedDictionaries>

Then I added two buttons to the home page and changed the source dictionaries to change the color of the frame.

MainWindow.xaml Code

<Button x:Name="DarkButton" Content="Dark" HorizontalAlignment="Left" Margin="151,132,0,0" VerticalAlignment="Top" Width="75" Click="DarkButton_Click"/>
    <Button x:Name="LightButton" Content="Light" HorizontalAlignment="Left" Margin="248,132,0,0" VerticalAlignment="Top" Width="75" Click="LightButton_Click"/>
    <Rectangle Fill="{DynamicResource ColorMode}" Width="100" Height="100"></Rectangle>

LightButton_Click Code

 private void LightButton_Click(object sender, RoutedEventArgs e)
    {
        var resources = Application.Current.Resources.MergedDictionaries;

        var existingResourceDictionary = Application.Current.Resources.MergedDictionaries
                                        .Where(rd => rd.Source != null)
                                        .SingleOrDefault(rd => Regex.Match(rd.Source.OriginalString, @"(\/((Light)|(Dark)))").Success);

        var source = $"pack://application:,,,/Light.xaml";
        var newResourceDictionary = new ResourceDictionary() { Source = new Uri(source) };

        Application.Current.Resources.MergedDictionaries.Remove(existingResourceDictionary);
        Application.Current.Resources.MergedDictionaries.Add(newResourceDictionary);
    }

DarkButton_Click

private void DarkButton_Click(object sender, RoutedEventArgs e)
    {
        var resources = Application.Current.Resources.MergedDictionaries;

        var existingResourceDictionary = Application.Current.Resources.MergedDictionaries
                                        .Where(rd => rd.Source != null)
                                        .SingleOrDefault(rd => Regex.Match(rd.Source.OriginalString, @"(\/((Light)|(Dark)))").Success);

        var source = $"pack://application:,,,/Dark.xaml";
        var newResourceDictionary = new ResourceDictionary() { Source = new Uri(source) };

        Application.Current.Resources.MergedDictionaries.Remove(existingResourceDictionary);
        Application.Current.Resources.MergedDictionaries.Add(newResourceDictionary);
    }

Don't forget to include the same color key in app.xaml.

<Application x:Class="ThemeExample.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:local="clr-namespace:ThemeExample"
         StartupUri="MainWindow.xaml">
<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary>
                <SolidColorBrush x:Key="ColorMode" Color="DarkBlue"/>
            </ResourceDictionary>
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>