AXAML Syntax Reference

Complete reference for Avalonia XAML (AXAML) syntax.

What I do

• Provide quick reference for AXAML root element structure
• Show correct namespace declarations (especially SukiUI)
• Explain property syntax (attribute vs element)
• Demonstrate data binding syntax shortcuts
• Show style selector patterns
• List markup extensions
• Highlight common mistakes and corrections

When to use me

Use this skill when you need to:

• Set up a new AXAML file with correct structure
• Add namespace declarations for SukiUI or custom types
• Choose between attribute and element property syntax
• Write style selectors for controls
• Use markup extensions like StaticResource or x:Static
• Fix common AXAML syntax errors
• Ensure proper SukiWindow setup

Basic Structure

Root Element

<UserControl xmlns="https://github.com/avaloniaui"
             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"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="600"
             x:Class="Namespace.Views.ViewName"
             x:DataType="vm:ViewModelName">
    <!-- Content -->
</UserControl>

Attributes:

• x:Class: Code-behind class (required)
• x:DataType: ViewModel type for compiled bindings (required)

Namespace Declarations

Standard:

xmlns="https://github.com/avaloniaui"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

SukiUI (Critical): Always use the URL-based namespace.

xmlns:suki="https://github.com/kikipoulet/SukiUI"

Custom:

xmlns:vm="using:YourApp.ViewModels"
xmlns:views="using:YourApp.Views"
xmlns:local="clr-namespace:YourApp"

Property Syntax

Attribute (Simple):

<Button Content="Click" Width="100" />

Element (Complex):

<Button>
    <Button.Content>
        <StackPanel>
            <TextBlock Text="A" />
            <TextBlock Text="B" />
        </StackPanel>
    </Button.Content>
</Button>

Data Binding

Modes: OneWay (default), TwoWay (input), OneTime, OneWayToSource

Syntax:

<!-- Property -->
<TextBlock Text="{Binding Name}" />

<!-- TwoWay (Input) -->
<TextBox Text="{Binding Name, Mode=TwoWay}" />

<!-- StringFormat -->
<TextBlock Text="{Binding Price, StringFormat='${0:F2}'}" />

<!-- Relative -->
<TextBlock Text="{Binding $parent[Window].Title}" />

<!-- Element -->
<TextBox Name="Input" />
<TextBlock Text="{Binding #Input.Text}" />

Styles

Selector Syntax:

<!-- Type -->
<Style Selector="Button">
    <Setter Property="Background" Value="Blue" />
</Style>

<!-- Class -->
<Style Selector="Button.Primary">
    <Setter Property="Background" Value="Red" />
</Style>

<!-- Pseudo-class -->
<Style Selector="Button:pointerover">
    <Setter Property="Opacity" Value="0.8" />
</Style>

<!-- Child combinator -->
<Style Selector="StackPanel > Button">
    <Setter Property="Margin" Value="5" />
</Style>

<!-- Descendant combinator -->
<Style Selector="Grid Button">
    <Setter Property="Padding" Value="10" />
</Style>

Usage:

<Button Classes="Primary" Content="Red Button" />

Markup Extensions

• {StaticResource Key}: Fixed resource
• {DynamicResource Key}: Dynamic resource (themes)
• {x:Static Class.Member}: Static member
• {x:Null}: Null value
• {Binding Path}: Data binding
• {CompiledBinding Path}: Explicit compiled binding
• {ReflectionBinding Path}: Opt-out of compiled binding

Examples:

<!-- Static Resource -->
<TextBlock Text="{StaticResource WelcomeMessage}" />

<!-- Dynamic Resource (for theming) -->
<Button Background="{DynamicResource ThemeBrush}" />

<!-- Static Property -->
<TextBlock TexStatic local:Constants.AppName}" />
<PathIcon Data="{x:Static icons:Icons.Home}" />

<!-- Null Value -->
<Button Command="{x:Null}" />

Best Practices

1. x:DataType: Always use for compiled bindings

2. SukiWindow: Use SukiWindow as root for main windows

   <suki:SukiWindow xmlns:suki="https://github.com/kikipoulet/SukiUI"
                    x:Class="YourApp.Views.MainWindow"
                    Title="My App"
                    Width="1200"
                    Height="800">
       <!-- Content -->
   </suki:SukiWindow>
   

3. Explicit Sizes: Set explicit Width and Height for windows

4. BulletDecorator: Deprecated. Use StackPanel with Orientation="Horizontal"

5. TwoWay Binding: Always explicit for input controls

   <TextBox Text="{Binding Name, Mode=TwoWay}" />
   

6. Namespace Prefixes: Use consistent, short prefixes

   • vm for ViewModels
   • views for Views
   • local for current namespace
   • suki for SukiUI

Common Mistakes

Mistake	Correction
Missing x:DataType	Add x:DataType="vm:MyVM"
xmlns:suki="using:..."	Use xmlns:suki="https://github.com/..."
<Window> with Suki	Use <suki:SukiWindow>
Default Binding on Input	Use Mode=TwoWay
Missing x:Class	Add x:Class="Namespace.Views.ViewName"

SukiUI Specific Patterns

SukiWindow Setup

<suki:SukiWindow xmlns="https://github.com/avaloniaui"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:suki="https://github.com/kikipoulet/SukiUI"
                 xmlns:vm="using:YourApp.ViewModels"
                 xmlns:views="using:YourApp.Views"
                 x:Class="YourApp.Views.MainWindow"
                 x:DataType="vm:MainWindowViewModel"
                 Title="My Application"
                 Width="1200"
                 Height="800">
    
    <!-- DataTemplates for navigation -->
    <suki:SukiWindow.DataTemplates>
        <DataTemplate DataType="vm:HomePageViewModel">
            <views:HomePage />
        </DataTemplate>
        <DataTemplate DataType="vm:SettingsPageViewModel">
            <views:Setting />
        </DataTemplate>
    </suki:SukiWindow.DataTemplates>
    
    <!-- Content -->
    <Grid>
        <!-- Your UI here -->
    </Grid>
</suki:SukiWindow>

SukiSideMenu

<suki:SukiSideMenu ItemsSource="{Binding Pages}"
                   SelectedItem="{Binding SelectedPage, Mode=TwoWay}"
                   HeaderContent="{Binding AppTitle}">
    <suki:SukiSideMenu.ItemTemplate>
        <DataTemplate>
            <suki:SukiSideMenuItem Header="{Binding DisplayName}">
                <suki:SukiSideMenuItem.Icon>
                    <PathIcon Data="{Binding Icon}" />
                </suki:SukiSideMenuItem.Icon>
            </suki:SukiSideMenuItem>
        </DataTemplate>
    </suki:SukiSideMenu.ItemTemplate>
</suki:SukiSideMenu>

Quick Troubleshooting

Binding not working?

• Check x:DataType is set
• Verify property exists in ViewModel
• Use Mode=TwoWay for input controls
• Check for typos in property names

SukiUI controls not found?

• Verify namespace: xmlns:suki="https://github.com/kikipoulet/SukiUI"
• Check NuGet package is installed
• Ensure using <suki:SukiWindow> not <Window>

Navigation not working?

• Define DataTemplates in SukiWindow
• Map each ViewModel to its View
• Ensure SelectedItem binding is TwoWay

Styles not applying?

• Check selector syntax
• Verify class names match
• Ensure styles are in correct scope (Window.Styles, UserControl.Styles, etc.)