Clock with dependency injection

Mårten Åsberg committed on 2026-06-04 at 23:00

Directory.Packages.props +2 -1

diff --git a/Directory.Packages.props b/Directory.Packages.props
index f116374..9a468b9 100644
@@ -15,5 +15,6 @@
    <PackageVersion Include="Avalonia.Fonts.Inter" Version="12.0.4" />
    <PackageVersion Include="AvaloniaUI.DiagnosticsSupport" Version="2.2.2" />
    <PackageVersion Include="CommunityToolkit.Mvvm" Version="8.4.2" />
    <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="11.0.0-preview.4.26230.115" />
  </ItemGroup>
</Project>
</Project>
\ No newline at end of file

src/App/App.axaml +0 -5

diff --git a/src/App/App.axaml b/src/App/App.axaml
index 8a3b957..78f2f97 100644
@@ -1,13 +1,8 @@
<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="MMirror.App.App"
             xmlns:local="using:MMirror.App"
             RequestedThemeVariant="Dark">
    <Application.DataTemplates>
        <local:ViewLocator/>
    </Application.DataTemplates>
    <Application.Styles>
        <FluentTheme />
    </Application.Styles>

src/App/App.axaml.cs +11 -2

diff --git a/src/App/App.axaml.cs b/src/App/App.axaml.cs
index 2799045..c4018e7 100644
@@ -1,6 +1,7 @@
using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;
using Microsoft.Extensions.DependencyInjection;
using MMirror.App.ViewModels;
using MMirror.App.Views;
@@ -15,13 +16,21 @@ public partial class App : Application
    public override void OnFrameworkInitializationCompleted()
    {
        var collection = new ServiceCollection();
        collection.AddViewModels();
        var services = collection.BuildServiceProvider();
        DataTemplates.Add(new ViewLocator(services));
        var vm = services.GetRequiredService<MainViewModel>();
        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
        {
            desktop.MainWindow = new MainWindow { DataContext = new MainViewModel() };
            desktop.MainWindow = new MainWindow { DataContext = vm };
        }
        else if (ApplicationLifetime is ISingleViewApplicationLifetime singleView)
        {
            singleView.MainView = new MainView { DataContext = new MainViewModel() };
            singleView.MainView = new MainView { DataContext = vm };
        }
        base.OnFrameworkInitializationCompleted();

src/App/App.csproj +1 -0

diff --git a/src/App/App.csproj b/src/App/App.csproj
index ad35dda..42285b2 100644
@@ -22,5 +22,6 @@
      <PrivateAssets Condition="'$(Configuration)' != 'Debug'">All</PrivateAssets>
    </PackageReference>
    <PackageReference Include="CommunityToolkit.Mvvm" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
  </ItemGroup>
</Project>

src/App/ViewLocator.cs +9 -24

diff --git a/src/App/ViewLocator.cs b/src/App/ViewLocator.cs
index a814054..b6590b7 100644
@@ -1,38 +1,23 @@
using System;
using System.Diagnostics.CodeAnalysis;
using Avalonia.Controls;
using Avalonia.Controls.Templates;
using Microsoft.Extensions.DependencyInjection;
using MMirror.App.ViewModels;
using MMirror.App.Views;
namespace MMirror.App;
/// <summary>
/// Given a view model, returns the corresponding view if possible.
/// </summary>
[RequiresUnreferencedCode(
    "Default implementation of ViewLocator involves reflection which may be trimmed away.",
    Url = "https://docs.avaloniaui.net/docs/concepts/view-locator"
)]
public class ViewLocator : IDataTemplate
public class ViewLocator(IServiceProvider services) : IDataTemplate
{
    public Control? Build(object? param)
    {
        if (param is null)
            return null;
        var name = param.GetType().FullName!.Replace("ViewModel", "View", StringComparison.Ordinal);
        var type = Type.GetType(name);
        if (type != null)
    public Control Build(object? data) =>
        data switch
        {
            return (Control)Activator.CreateInstance(type)!;
        }
        return new TextBlock { Text = "Not Found: " + name };
    }
            MainViewModel => services.GetRequiredService<MainView>(),
            _ => new TextBlock { Text = $"No view for {data?.GetType().Name}" },
        };
    public bool Match(object? data)
    {
        return data is ViewModelBase;
    }
    public bool Match(object? data) => data is ViewModelBase;
}

src/App/ViewModels/MainViewModel.cs +49 -2

diff --git a/src/App/ViewModels/MainViewModel.cs b/src/App/ViewModels/MainViewModel.cs
index 0dc7f9b..a8bd765 100644
@@ -1,6 +1,53 @@
﻿namespace MMirror.App.ViewModels;
﻿using System;
using Avalonia.Threading;
using CommunityToolkit.Mvvm.ComponentModel;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
namespace MMirror.App.ViewModels;
public partial class MainViewModel : ViewModelBase
{
    public string Greeting { get; } = "Welcome to Avalonia!";
    private readonly TimeProvider timeProvider;
    private readonly DispatcherTimer dispatcherTimer;
    [ObservableProperty]
    public partial DateTimeOffset CurrentTime { get; private set; }
    public MainViewModel(TimeProvider timeProvider)
    {
        this.timeProvider = timeProvider;
        CurrentTime = timeProvider.GetLocalNow();
        dispatcherTimer = new DispatcherTimer() { Interval = TimeSpan.FromSeconds(1) };
        dispatcherTimer.Tick += OnTick;
    }
    public void SubscribeToUpdates()
    {
        dispatcherTimer.Start();
    }
    private void OnTick(object? sender, EventArgs e)
    {
        CurrentTime = timeProvider.GetLocalNow();
    }
    public void UnsubscribeFromUpdates()
    {
        dispatcherTimer.Stop();
    }
}
internal static class MainViewModelServiceCollectionExtensions
{
    extension(IServiceCollection services)
    {
        public IServiceCollection AddMainViewModel()
        {
            services.TryAddSingleton(TimeProvider.System);
            services.AddTransient<MainViewModel>();
            return services;
        }
    }
}

src/App/ViewModels/ServiceCollectionExtensions.cs +11 -0

diff --git a/src/App/ViewModels/ServiceCollectionExtensions.cs b/src/App/ViewModels/ServiceCollectionExtensions.cs
new file mode 100644
index 0000000..388f511
@@ -0,0 +1,11 @@
using Microsoft.Extensions.DependencyInjection;
namespace MMirror.App.ViewModels;
internal static class ServiceCollectionExtensions
{
    extension(IServiceCollection services)
    {
        public IServiceCollection AddViewModels() => services.AddMainViewModel();
    }
}

src/App/Views/MainView.axaml +2 -3

diff --git a/src/App/Views/MainView.axaml b/src/App/Views/MainView.axaml
index 7498754..881bce4 100644
@@ -7,13 +7,12 @@
             x:Class="MMirror.App.Views.MainView"
             x:DataType="vm:MainViewModel">
    <Design.DataContext>
        <!-- This only sets the DataContext for the previewer in an IDE,
        to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
        <vm:MainViewModel />
    </Design.DataContext>
    <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Spacing="8">
        <TextBlock Text="{Binding Greeting}"/>
        <TextBlock Text="{Binding CurrentTime, StringFormat=HH:mm:ss}"/>
        <TextBlock Text="{Binding CurrentTime, StringFormat=yyyy-MM-dd}"/>
        <Rectangle Width="32" Height="32" Fill="#bada55" />
    </StackPanel>
</UserControl>

src/App/Views/MainView.axaml.cs +22 -0

diff --git a/src/App/Views/MainView.axaml.cs b/src/App/Views/MainView.axaml.cs
index 44f20ae..ac48bc1 100644
@@ -1,4 +1,6 @@
using Avalonia;
using Avalonia.Controls;
using MMirror.App.ViewModels;
namespace MMirror.App.Views;
@@ -8,4 +10,24 @@ public partial class MainView : UserControl
    {
        InitializeComponent();
    }
    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
    {
        base.OnAttachedToVisualTree(e);
        if (DataContext is MainViewModel vm)
        {
            vm.SubscribeToUpdates();
        }
    }
    protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
    {
        if (DataContext is MainViewModel vm)
        {
            vm.UnsubscribeFromUpdates();
        }
        base.OnDetachedFromVisualTree(e);
    }
}

src/App/Views/ServiceCollectionExtensions.cs +11 -0

diff --git a/src/App/Views/ServiceCollectionExtensions.cs b/src/App/Views/ServiceCollectionExtensions.cs
new file mode 100644
index 0000000..60282f7
@@ -0,0 +1,11 @@
using Microsoft.Extensions.DependencyInjection;
namespace MMirror.App.Views;
internal static class ServiceCollectionExtensions
{
    extension(IServiceCollection services)
    {
        public IServiceCollection AddViews() => services.AddTransient<MainView>().AddTransient<MainWindow>();
    }
}

src/App/packages.lock.json +7 -1

diff --git a/src/App/packages.lock.json b/src/App/packages.lock.json
index f4238bc..48a3ef9 100644
@@ -76,6 +76,12 @@
        "resolved": "1.2.6",
        "contentHash": "KMSJG+jfk7vjP52QkWB99qWespXCPAzG/IaMCMRHYWumJEAGKQYm2HtyWG6eqnOwDitH96i1cqq5EVesyOtPmg=="
      },
      "Microsoft.Extensions.DependencyInjection": {
        "type": "Direct",
        "requested": "[11.0.0-preview.4.26230.115, )",
        "resolved": "11.0.0-preview.4.26230.115",
        "contentHash": "v+F34r5W5XgR95xG0Te2KyYmCDnkc4kljLMGEZ30WKQjAzuXz/pLTEvsRNYxNJUzfKPI0H4oqLglyHZkCe1lYw=="
      },
      "Avalonia.Angle.Windows.Natives": {
        "type": "Transitive",
        "resolved": "2.1.27548.20260419",
@@ -506,4 +512,4 @@
      }
    }
  }
}
}
\ No newline at end of file