xaml-csharp-development-skill-for-avalonia

WPF Freezable, Brushes, Images, Media, and Immutability Patterns to Avalonia

Table of Contents

1. Scope and APIs
2. Immutability Mapping
3. Conversion Example
4. Avalonia C# Equivalent
5. Troubleshooting

Scope and APIs

Primary WPF APIs:

• Freezable
• mutable/frozen Brush and geometry resources
• image/media resource patterns

Primary Avalonia APIs:

• immutable brush interfaces (IImmutableBrush, ImmutableSolidColorBrush, etc.)
• Brushes and brush conversion (ToImmutable())
• Bitmap and image source assets

Immutability Mapping

WPF	Avalonia
Freezable.Freeze() for reuse	prefer immutable brush/image resources and shared static resources
mutable brush in hot draw paths	convert to immutable where appropriate
ImageSource resources	Avalonia Bitmap/asset URI image sources

Conversion Example

WPF C#:

var brush = new SolidColorBrush(Colors.DodgerBlue);
if (brush.CanFreeze)
    brush.Freeze();

Avalonia XAML:

<Border xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Background="DodgerBlue"
        Width="120"
        Height="40" />

Avalonia C# Equivalent

using Avalonia.Media;
using Avalonia.Media.Immutable;

IImmutableSolidColorBrush accent = new ImmutableSolidColorBrush(Colors.DodgerBlue);

var mutable = new SolidColorBrush(Colors.DodgerBlue);
var immutable = mutable.ToImmutable();

Troubleshooting

1. draw path allocations increase after migration.
   • reuse immutable brushes/pens and avoid per-frame object creation.
2. asset images fail in packaged builds.
   • verify URI and resource packaging strategy.
3. attempting direct Freezable API parity.
   • shift to immutable resource reuse patterns.

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