Add shared SVG animation runtime and host playback backends

.gitignore

@@ -295,3 +295,6 @@ __pycache__/
 
 # macOS
 .DS_Store
+/output
+/.playwright-cli
+TestApp.json

AGENTS.md

@@ -14,6 +14,23 @@ This repository contains the Svg.Skia library and associated tests. The followin
 3. Build the solution using `dotnet build Svg.Skia.slnx -c Release`.
 4. Run all tests with `dotnet test Svg.Skia.slnx -c Release`.
 
+## W3C Chrome Overrides
+- Files under `tests/Svg.Skia.UnitTests/ChromeReference/W3C/` must be generated from real Google Chrome captures, not copied from the legacy W3C PNG set.
+- Use `node scripts/capture_w3c_chrome_overrides.mjs` to regenerate the checked Chrome override set. Pass specific test names as comma-separated arguments to limit capture scope, for example `node scripts/capture_w3c_chrome_overrides.mjs masking-path-04-b,linking-a-09-b`.
+- The capture script serves the repository over HTTP and screenshots a `480x360` Chrome-hosted iframe, which matches the standalone viewport policy used by `W3CTestSuiteTests`.
+- When a Chrome override exists, keep `W3CTestSuiteTests` pointed at that override instead of the W3C reference PNG.
+- Do not reintroduce footer exclusion regions for W3C comparisons. Prefer Chrome overrides plus narrowly-scoped per-test thresholds only when the library is visually aligned with Chrome but still differs at the pixel-raster level.
+- If a W3C fixture depends on JavaScript, DOM APIs, or browser-only runtime behavior that Svg.Skia does not implement, keep that row skipped with an explicit reason instead of manufacturing a fake baseline.
+
+## Testing Workflow
+- For W3C work, first run focused rows with `dotnet test tests/Svg.Skia.UnitTests/Svg.Skia.UnitTests.csproj -f net10.0 -c Release --no-restore --filter "FullyQualifiedName~W3CTestSuiteTests.Tests"`.
+- When refreshing baselines, rerun the focused W3C subset that changed before running the full W3C suite.
+- Before committing renderer or baseline changes, run:
+  - `dotnet format Svg.Skia.slnx --no-restore`
+  - `dotnet build Svg.Skia.slnx -c Release`
+  - `dotnet test Svg.Skia.slnx -c Release`
+- Keep unrelated local state files, especially `samples/TestApp/TestApp.json`, out of commits unless the task explicitly requires them.
+
 ## Commit Guidelines
 - Use concise commit messages summarizing your change in under 72 characters.
 - Additional description lines may follow the summary if necessary.

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Svg.Skia Changelog
 
+## Unreleased
+
+* Added SVG 1.1 animation object-model coverage in `Svg.Custom` for `animate`, `set`, `animateMotion`, `animateColor`, `animateTransform`, and `mpath`.
+* Added typed `pointer-events` support, geometry-aware hit testing, topmost-element targeting, and routed interaction dispatch with capture, tunnel, bubble, and cursor resolution.
+* Added shared animation playback in `SKSvg`, including animation time control, invalidation events, layered redraw, throttling helpers, and native-composition scene extraction.
+* Added host animation backends for Avalonia and Uno, including resolved-backend diagnostics and Avalonia retained `NativeComposition` playback with fallback.
+* Added an animation benchmark harness in `tests/Svg.Skia.Benchmarks` and exposed animation/backend controls in `samples/TestApp`.
+
 ## 0.3.0
 
 * Updated NuGet packages.

Directory.Packages.props

@@ -33,6 +33,7 @@
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
     <PackageVersion Include="SixLabors.ImageSharp" Version="3.1.11" />
+    <PackageVersion Include="BenchmarkDotNet" Version="0.13.12" />
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.abstractions" Version="2.0.3" />
     <PackageVersion Include="xunit.assert" Version="2.9.3" />

README.md

@@ -18,9 +18,8 @@
 ## About
 
 *Svg.Skia* can be used as a .NET library or as a CLI application
-to render SVG files based on a [static](http://www.w3.org/TR/SVG11/feature#SVG-static)
-[SVG Full 1.1](https://www.w3.org/TR/SVG11/) subset to raster images or
-to a backend's canvas.
+to render SVG files based on the [SVG Full 1.1](https://www.w3.org/TR/SVG11/)
+document model to raster images or to a backend's canvas.
 
 The `Svg.Skia` is using [SVG](https://github.com/vvvv/SVG) library to load `Svg` object model. 
 
@@ -33,6 +32,15 @@ The `Svg.Skia` can be used in same way as the [SkiaSharp.Extended.Svg](https://g
 The `Svg` library has a more complete implementation of the `Svg` document model than [SkiaSharp.Extended.Svg](https://github.com/mono/SkiaSharp.Extended/tree/main/source/SkiaSharp.Extended.Svg)
 and the `Svg.Skia` renderer will provide more complete rendering subsystem implementation.
 
+## Highlights
+
+- `Svg.Custom` now exposes the SVG 1.1 animation object model for `animate`, `set`, `animateMotion`, `animateColor`, `animateTransform`, and `mpath`.
+- `Svg.Custom` and `Svg.Skia` now include typed `pointer-events` handling plus geometry-aware topmost hit testing.
+- `Svg.Skia` now includes a shared interaction dispatcher, shared animation clock/controller, and host-driven animation playback APIs.
+- `Svg.Controls.Skia.Avalonia` and `Svg.Controls.Skia.Uno` now expose animation backend selection, playback rate, frame interval, and resolved-backend diagnostics.
+- Avalonia adds an optional `NativeComposition` animation backend with fallback to `RenderLoop` or `DispatcherTimer` when retained composition is unavailable.
+- `tests/Svg.Skia.Benchmarks` adds a local BenchmarkDotNet harness for the shared animation renderer, and `samples/TestApp` exposes backend and playback controls for manual verification.
+
 ## NuGet
 
 Svg.Skia is delivered as a NuGet package.
@@ -202,7 +210,7 @@ The `SKSvg` class provides helpers for retrieving elements or drawables at a
 given point. The hit-testing methods expect coordinates in picture space:
 
 ```C#
-using SkiaSharp;
+using ShimSkiaSharp;
 using Svg.Skia;
 
 var svg = new SKSvg();
@@ -220,6 +228,10 @@ When drawing on a transformed canvas you can convert canvas coordinates to
 picture coordinates using `TryGetPicturePoint` and then use the hit-testing
 methods.
 
+The runtime also exposes `HitTestTopmostElement(...)` for pointer-dispatch
+scenarios where only the topmost routed target should be returned, and the hit
+test path now respects typed `pointer-events` values.
+
 #### Svg control
 
 The `Svg` Avalonia control exposes a `HitTestElements` method that accepts
@@ -229,6 +241,47 @@ a point in control coordinates and returns the matching SVG elements:
 var hits = svgControl.HitTestElements(new Point(x, y));
 ```
 
+### Animation and interaction
+
+`SKSvg` now exposes a shared animation runtime and a routed interaction layer
+that can be hosted from Avalonia, Uno, or custom Skia surfaces.
+
+```C#
+using System;
+using ShimSkiaSharp;
+using Svg.Skia;
+
+using var svg = new SKSvg();
+
+if (svg.Load("animated.svg") is not null && svg.HasAnimations)
+{
+    svg.AnimationInvalidated += (_, e) => Console.WriteLine(e.Time);
+
+    svg.SetAnimationTime(TimeSpan.FromSeconds(1));
+    svg.AdvanceAnimation(TimeSpan.FromMilliseconds(16));
+    svg.ResetAnimation();
+}
+
+var target = svg.HitTestTopmostElement(new SKPoint(10, 10));
+```
+
+The shared runtime surface includes:
+
+- `HasAnimations`
+- `AnimationTime`
+- `SetAnimationTime(...)`
+- `AdvanceAnimation(...)`
+- `ResetAnimation()`
+- `AnimationInvalidated`
+- `AnimationMinimumRenderInterval`
+- `HasPendingAnimationFrame`
+- `FlushPendingAnimationFrame()`
+- `LastAnimationDirtyTargetCount`
+
+The shared interaction surface includes `SvgInteractionDispatcher`,
+`SvgPointerInput`, routed `Dispatched` events, cursor hints, and optional
+compatibility bridging back into `SvgElement` mouse events.
+
 
 ### Avalonia
 
@@ -248,6 +301,26 @@ Install-Package Svg.Controls.Skia.Avalonia
 <Svg Path="/Assets/__AJ_Digital_Camera.svg"/>
 ```
 
+For animated content, the Skia-backed Avalonia and Uno controls also expose:
+
+- `AnimationBackend`
+- `AnimationFrameInterval`
+- `AnimationPlaybackRate`
+- `ActualAnimationBackend`
+- `AnimationBackendFallbackReason`
+
+Avalonia supports `Default`, `Manual`, `DispatcherTimer`, `RenderLoop`, and
+`NativeComposition`. Uno supports the same host-driven playback model but falls
+back from `NativeComposition` because it does not currently expose a working
+retained child-visual path.
+
+```XAML
+<Svg Path="/Assets/animated.svg"
+     AnimationBackend="Default"
+     AnimationPlaybackRate="1.0"
+     AnimationFrameInterval="0:0:0.016" />
+```
+
 #### Image control
 
 ```XAML

Svg.Skia.slnx

@@ -66,7 +66,9 @@
     <Project Path="samples/Svg.SourceGenerator.Skia.Sample/Svg.SourceGenerator.Skia.Sample.csproj" />
     <Project Path="samples/svgc/svgc.csproj" />
     <Project Path="samples/SvgToPng/SvgToPng.csproj" />
+    <Project Path="samples/TestApp.Shared/TestApp.Shared.csproj" />
     <Project Path="samples/TestApp/TestApp.csproj" />
+    <Project Path="samples/UnoTestApp/UnoTestApp.csproj" />
   </Folder>
   <Folder Name="/src/">
     <Project Path="src/ShimSkiaSharp/ShimSkiaSharp.csproj" />
@@ -81,11 +83,14 @@
     <Project Path="src/Svg.Controls.Skia.Uno/Svg.Controls.Skia.Uno.csproj" />
     <Project Path="src/Svg.Controls.Skia.Avalonia/Svg.Controls.Skia.Avalonia.csproj" />
     <Project Path="src/Svg.Model/Svg.Model.csproj" />
+    <Project Path="src/Svg.Animation/Svg.Animation.csproj" />
+    <Project Path="src/Svg.SceneGraph/Svg.SceneGraph.csproj" />
     <Project Path="src/Svg.Skia/Svg.Skia.csproj" />
     <Project Path="src/Svg.SourceGenerator.Skia/Svg.SourceGenerator.Skia.csproj" />
   </Folder>
   <Folder Name="/tests/">
     <Project Path="tests/ShimSkiaSharp.UnitTests/ShimSkiaSharp.UnitTests.csproj" />
+    <Project Path="tests/Svg.Skia.Benchmarks/Svg.Skia.Benchmarks.csproj" />
     <Project Path="tests/Svg.Controls.Avalonia.UnitTests/Svg.Controls.Avalonia.UnitTests.csproj" />
     <Project Path="tests/Svg.Controls.Skia.Avalonia.UnitTests/Svg.Controls.Skia.Avalonia.UnitTests.csproj" />
     <Project Path="tests/Svg.Controls.Skia.Uno.UnitTests/Svg.Controls.Skia.Uno.UnitTests.csproj" />

plan/animation-project-split-plan.md

@@ -0,0 +1,76 @@
+# Animation Project Split Plan
+
+## Goal
+
+Split the reusable animation runtime out of `src/Svg.Skia` into a dedicated project, similar to `src/Svg.SceneGraph`, while keeping `SKSvg`-specific render orchestration inside `Svg.Skia`.
+
+## Why
+
+- reduce `Svg.Skia` assembly scope to Skia/render-host integration
+- make the animation runtime reusable by controls and future backends without pulling in all of `SKSvg`
+- isolate trim/AOT-sensitive animation logic behind a smaller assembly boundary
+- align the architecture with the retained-scene split already introduced by `Svg.SceneGraph`
+
+## Clean Boundary
+
+### Move to `src/Svg.Animation`
+
+- `SvgAnimationClock`
+- `SvgAnimationController`
+- `SvgAnimationFrameState`
+- `SvgAnimationHostBackend` and resolver/capability types
+- `SvgNativeCompositionScene`, `SvgNativeCompositionFrame`, `SvgNativeCompositionLayer`
+- shared animation invalidation policy extracted from `SKSvg.AnimationLayers.cs`
+
+### Keep in `src/Svg.Skia`
+
+- `SKSvg.Model.cs` animation orchestration
+- `SKSvg.AnimationLayers.cs`
+- `SKSvg.NativeComposition.cs`
+- `SKSvg.SceneGraph.cs` retained-scene mutation/render preparation
+- SkiaSharp picture conversion, picture registration/disposal, and drawing
+
+Reason: those files are partial `SKSvg` implementation details and depend directly on `SKSvg` state, `SkiaModel`, and render lifecycle synchronization.
+
+## Dependency Rules
+
+### `Svg.Animation`
+
+- may reference:
+  - `Svg.Custom`
+  - `Svg.Model`
+  - `ShimSkiaSharp`
+  - `SkiaSharp`
+- must not depend on:
+  - `SKSvg`
+  - `Svg.Controls.*`
+  - retained-scene orchestration partials
+
+### `Svg.Skia`
+
+- references:
+  - `Svg.Animation`
+  - `Svg.SceneGraph`
+  - existing model/custom projects
+
+## Required Supporting Changes
+
+1. Add `InternalsVisibleTo` from `Svg.Custom` to `Svg.Animation`.
+2. Add `src/Svg.Animation/Properties/AssemblyInfo.cs` with `InternalsVisibleTo` for `Svg.Skia`.
+3. Add the new project to `Svg.Skia.slnx`.
+4. Update `Svg.Skia.csproj` to reference `Svg.Animation.csproj`.
+5. Physically move animation runtime files from `src/Svg.Skia/Animation` to `src/Svg.Animation`.
+6. Replace the inherited-animation-attribute table in `SKSvg.AnimationLayers.cs` with a shared helper owned by `Svg.Animation`.
+
+## Validation
+
+1. `dotnet format Svg.Skia.slnx --no-restore`
+2. `dotnet build Svg.Skia.slnx -c Release`
+3. `dotnet test Svg.Skia.slnx -c Release`
+
+## Success Criteria
+
+- `src/Svg.Skia/Animation` no longer contains the reusable runtime files
+- `Svg.Skia` builds against the new project boundary
+- Avalonia/Uno host backends and tests continue to compile against the moved types
+- `SKSvg.AnimationLayers.cs` retains only `SKSvg`-bound logic