AvaDiagnostics12 12.1.1

AvaDiagnostics12

An unofficial community fork of the legacy Avalonia.Diagnostics in-process DevTools, updated to build and run against Avalonia 12.

Not affiliated with or endorsed by the AvaloniaUI project. The upstream package was archived and deprecated in favour of the standalone AvaloniaUI Developer Tools — see Upstream alternative below.

Install

dotnet add package AvaDiagnostics12

Usage

The public API is unchanged from the original package — the namespaces are still Avalonia.Diagnostics.*, so existing code needs no edits:

public override void OnFrameworkInitializationCompleted()
{
    if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
    {
        desktop.MainWindow = new MainWindow();
#if DEBUG
        desktop.MainWindow.AttachDevTools();
#endif
    }

    base.OnFrameworkInitializationCompleted();
}

Press F12 to open the DevTools window.

What changed from upstream

• Ported to the Avalonia 12 input APIs (RawInputEventArgs.Root and PointerOverRoot are now IInputRoot rather than Visual), including hotkey and pointer-position handling over popup roots.
• The NuGet package id is AvaDiagnostics12, so this fork is never confused with the official Avalonia.Diagnostics package at install time.

Tests

dotnet test Avalonia.Diagnostics.slnx

tests/Avalonia.Diagnostics.UnitTests covers the view models, the filter and conversion helpers, and the Avalonia 11 → 12 port fixes that compile cleanly but break at runtime. UI-thread tests use Avalonia.Headless via [AvaloniaFact]/[AvaloniaTheory] (xunit v3); the rest are plain [Fact]s.

Nearly everything in this library is internal, so the test project is granted access through src/Avalonia.Diagnostics/Properties/InternalsVisibleTo.cs and is signed with the same build/avalonia.snk. That grant does not extend to Avalonia's own internals — tests cannot name types such as InputManager, TopLevel.InputRoot or LayoutManager, and RawKeyEventArgs has no publicly reachable constructor. Where that got in the way, the logic under test was split into a helper taking only public types rather than reached by reflection, so a rename still breaks the test.

Not covered: VisualExtensions.RenderTo (needs real Skia rendering, not the default headless platform) and the popup-freeze / hotkey input plumbing in Views/MainWindow (needs synthesized raw input against live popup roots).

Known limitation: assembly identity

The shipped assembly is still named Avalonia.Diagnostics and is still strong-named with AvaloniaUI's key. This is not a cosmetic leftover — Avalonia 12 exposes the internals this code needs (InputManager, IRenderer, IClassesChangedListener) through [assembly: InternalsVisibleTo("Avalonia.Diagnostics", PublicKey=…)]. Renaming the assembly or signing with a different key fails the build with CS0122.

Consequence: do not reference AvaDiagnostics12 and the official Avalonia.Diagnostics package in the same project — both produce an Avalonia.Diagnostics.dll and the build will fail with a file conflict. Use one or the other.

Upstream alternative

If you don't need the classic in-process window, the maintained replacement is:

dotnet add package AvaloniaUI.DiagnosticsSupport
dotnet tool install --global AvaloniaUI.DeveloperTools

Then call this.AttachDeveloperTools() in Application.Initialize() and press F12. It includes a free Community edition covering everything the legacy package did. See the Developer Tools documentation.

License

MIT — see LICENSE. Original code copyright © The AvaloniaUI Project. Everything in this fork is released under the same MIT license; do whatever you like with it.