xaml-csharp-development-skill-for-avalonia

WPF Dependency Property System to Avalonia Property System

Table of Contents

1. Scope and APIs
2. Property System Mapping
3. Conversion Example
4. Avalonia C# Equivalent
5. AOT Notes
6. Troubleshooting

Scope and APIs

Primary WPF APIs:

• DependencyObject, DependencyProperty
• DependencyProperty.Register, RegisterAttached, RegisterReadOnly
• FrameworkPropertyMetadata

Primary Avalonia APIs:

• AvaloniaObject, AvaloniaProperty
• AvaloniaProperty.Register, RegisterAttached, RegisterDirect
• StyledProperty<T>, DirectProperty<TOwner, TValue>

Property System Mapping

WPF	Avalonia
DependencyProperty	AvaloniaProperty
FrameworkPropertyMetadata	property registration options + changed callbacks
RegisterReadOnly	DirectProperty with private setter backing field
attached property via RegisterAttached	attached property via AvaloniaProperty.RegisterAttached

Conversion Example

WPF C#:

public class HeaderCard : Control
{
    public static readonly DependencyProperty TitleProperty =
        DependencyProperty.Register(
            nameof(Title),
            typeof(string),
            typeof(HeaderCard),
            new FrameworkPropertyMetadata(string.Empty));

    public string Title
    {
        get => (string)GetValue(TitleProperty);
        set => SetValue(TitleProperty, value);
    }
}

Avalonia XAML usage:

<local:HeaderCard xmlns="https://github.com/avaloniaui"
                  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                  xmlns:local="using:MyApp.Controls"
                  Title="Revenue" />

Avalonia C# Equivalent

using Avalonia;
using Avalonia.Controls;

public class HeaderCard : Control
{
    public static readonly StyledProperty<string> TitleProperty =
        AvaloniaProperty.Register<HeaderCard, string>(nameof(Title), string.Empty);

    public string Title
    {
        get => GetValue(TitleProperty);
        set => SetValue(TitleProperty, value);
    }
}

Attached property pattern:

public static readonly AttachedProperty<bool> IsHighlightedProperty =
    AvaloniaProperty.RegisterAttached<HeaderCard, Control, bool>("IsHighlighted");

AOT Notes

• keep property registrations strongly typed and static.
• avoid reflection-based property lookup when typed APIs are available.

Troubleshooting

1. Property changes do not update style/template.
   • ensure property is registered as StyledProperty and used in style selectors/setters.
2. read-only property migration fails.
   • use RegisterDirect with explicit getter/setter backing field pattern.
3. attached property set/get methods missing.
   • expose static helper methods for ergonomics where needed.

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