xaml-csharp-development-skill-for-avalonia

WPF Dispatcher, BackgroundWorker, Timers, and Async Workflows to Avalonia

Table of Contents

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

Scope and APIs

Primary WPF APIs:

• Dispatcher
• DispatcherTimer
• BackgroundWorker

Primary Avalonia APIs:

• Dispatcher.UIThread
• DispatcherTimer
• Task.Run + dispatcher marshaling

Threading Mapping

WPF	Avalonia
Dispatcher.Invoke	Dispatcher.UIThread.InvokeAsync
Dispatcher.BeginInvoke	Dispatcher.UIThread.Post
DispatcherTimer	DispatcherTimer
BackgroundWorker	Task.Run + progress callbacks to UI thread

Conversion Example

WPF C#:

Dispatcher.BeginInvoke(() => Status = "Running");

var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
timer.Tick += (_, _) => Clock = DateTime.Now.ToString("T");
timer.Start();

Avalonia XAML:

<StackPanel xmlns="https://github.com/avaloniaui"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:vm="using:MyApp.ViewModels"
            x:DataType="vm:RuntimeViewModel"
            Spacing="8">
  <TextBlock Text="{CompiledBinding StatusText}" />
  <TextBlock Text="{CompiledBinding ClockText}" />
</StackPanel>

Avalonia C# Equivalent

using System;
using System.Threading.Tasks;
using Avalonia.Threading;

Dispatcher.UIThread.Post(() => viewModel.StatusText = "Running");

var timer = new DispatcherTimer
{
    Interval = TimeSpan.FromSeconds(1)
};

timer.Tick += (_, _) => viewModel.ClockText = DateTime.Now.ToString("T");
timer.Start();

await Task.Run(() =>
{
    var result = Compute();
    Dispatcher.UIThread.Post(() => viewModel.ApplyResult(result));
});

Troubleshooting

1. UI updates throw thread access errors.
   • marshal to Dispatcher.UIThread for all UI mutations.
2. timer callback performs heavy work.
   • keep tick handlers lightweight and move heavy work off thread.
3. migrated async flow deadlocks.
   • avoid blocking waits (Wait, Result) on UI thread.

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