How to Use Included Styles

This guide shows you how to share styles from a separate styles file (that is included in your application). This approach allows you to share styles across multiple applications.

To do this, you define styles in a new XAML file. Here, the root element must then be either a Style or Styles element. For example:

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style Selector="TextBlock.h1">
        <Setter Property="FontSize" Value="24"/>
        <Setter Property="FontWeight" Value="Bold"/>
    </Style>
</Styles>

The Avalonia UI solution templates provide a quick way of adding a styles file to your project. Follow this procedure:

• In the Solution Explorer, right-click your project.
• Click Add and New Item
• From the Avalonia Items, click Styles (Avalonia)
• Type a name for your styles file

To use the styles defined in a separate file, you must reference it using a StyleInclude element. The source attribute defines the location of the styles file. You can choose the level at which to add this element.

For example, to use styles defined in a file AppStyles.axaml (saved in the folder /Styles), you could write a a StyleInclude element in the window like this:

<Window ... >
    <Window.Styles>
        <StyleInclude Source="/Styles/AppStyles.axaml" />
    </Window.Styles>

    <StackPanel>
       <TextBlock Classes="h1">Heading 1</TextBlock>
       <TextBlock>This is not a heading and will not be changed.</TextBlock>
    </StackPanel>
</Window>

However, it is more common to reference a styles file in the App.axaml file like this:

<Application... > 
    <Application.Styles>
        <FluentTheme Mode="Light"/>
        <StyleInclude Source="/AppStyles.axaml"/>
    </Application.Styles>
</Application>

This will allow you to use the styles from the separate file throughout your application.

You can also include styles from a another assembly by using the avares:// prefix:

<Application... > 
    <Application.Styles>
        <FluentTheme Mode="Light"/>
        <StyleInclude Source="avares://MyApp.Shared/Styles/CommonAppStyles.axaml"/>
    </Application.Styles>
</Application>

will reference the /Styles/CommonAppStyles.axaml file from the MyApp.Shared project.