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Rendering Pipeline

At a high level, the render path is:

  1. Parse markup into SVG document objects.
  2. Compile the document into a retained SvgSceneDocument.
  3. Render that retained scene into the intermediate ShimSkiaSharp.SKPicture model.
  4. Materialize the shim model as a SkiaSharp.SKPicture.
  5. Draw the picture, export it, or expose it through Avalonia and Uno.

Parsing

Svg.Custom supplies the SVG document object model. SvgService is the main entry point used across the repository to open or parse documents.

Retained-scene compilation

Svg.SceneGraph compiles a SvgDocument or SvgFragment into SvgSceneDocument. That retained scene graph stores:

  • the compiled SvgSceneNode tree,
  • resource dependency indexes,
  • compilation-root boundaries for incremental mutation refresh,
  • hit-test geometry and bounds,
  • the document instance that backs the current scene.

SvgSceneRuntime.TryCompile(...) is the repository's main entry point for this phase.

Shim-model generation

SvgSceneDocument.CreateModel() renders the retained scene into a ShimSkiaSharp.SKPicture command model. That model is still CPU-side data, which makes it safe to inspect, clone, or mutate before creating a native SkiaSharp picture.

Picture materialization

Svg.Skia.SKSvg owns:

  • the original source information,
  • the current SvgDocument,
  • the retained SvgSceneDocument,
  • the ShimSkiaSharp model, and
  • the lazily created SkiaSharp.SKPicture.

During a normal Load(...), FromSvg(...), or FromSvgDocument(...) call, SKSvg compiles the retained scene, renders a shim model from it, and refreshes the current Picture.

After that:

  • SourceDocument exposes the authored DOM,
  • RetainedSceneGraph exposes the compiled scene,
  • Model exposes the shim picture model,
  • Picture exposes the native SkiaSharp.SKPicture.

That separation is what allows the runtime to support DOM mutation, retained-scene refresh, hit testing, model editing, and export without reparsing source text on every operation.

Avalonia integration

The Avalonia packages sit on top of the same conceptual steps:

  • SvgSource loads and retains the source data.
  • SvgImage exposes it as an IImage.
  • Svg wraps it as a control.
  • SvgResourceExtension turns it into a reusable brush.

Output paths

Once you have an SKPicture, the repository exposes helpers for:

  • drawing to SKCanvas,
  • raster output through ToBitmap() and ToImage(),
  • vector output through ToSvg(),
  • document output through ToPdf() and ToXps().

For the practical loading and mutation workflows built on top of this pipeline, see Loading SVG, SvgDocument, and VectorDrawable, Retained Scene Graph Usage, and Performance and Retained-Scene Refresh.