Chromium SVG Migration Status

A snapshot of which Blink rendering systems SVG participates in fully, which have been migrated, and which are stable in their current form. As of mid-2026 on the main Chromium branch.

Layout: LayoutNG migration

Subsystem	Status	Notes
HTML legacy box layout	Removed (~2022)	All HTML on LayoutNG. The "legacy box tree" no longer exists.
SVG <text>, <tspan>, <textPath>	LayoutNG	LayoutSVGText extends LayoutSVGBlock extends LayoutBlockFlow. Header at core/layout/svg/layout_svg_text.h:13 literally says "the LayoutNG representation of SVG <text>." See text.md.
SVG <foreignObject>	LayoutNG	LayoutSVGForeignObject extends LayoutSVGBlock extends LayoutBlockFlow. HTML descendants get full LayoutNG. See use-and-foreign-object.md.
SVG shapes (<path>, <circle>, <rect>, ...)	SVG-specific (UpdateSVGLayout)	No public roadmap to migrate.
SVG containers (<g>, viewport containers)	SVG-specific	No public roadmap to migrate.
SVG resources (<defs>, <linearGradient>, <pattern>, ...)	SVG-specific	No public roadmap to migrate.
SVG <image>	SVG-specific (extends LayoutSVGModelObject)	No public roadmap to migrate.

The position is that LayoutNG's constraint-space algorithm is designed for CSS box layout, and SVG's attribute-driven, transform-baked-in geometry doesn't benefit from migration. Text and <foreignObject> migrated because they reuse complex inline / block-flow logic that's hard to duplicate.

Paint: BlinkGenPropertyTrees / CompositeAfterPaint

Subsystem	Status
Property trees built by Blink (PrePaint)	Complete (~2020)
SVG transforms participate in TransformPaintPropertyNode	✓
SVG clip-path participates in ClipPaintPropertyNode	✓
SVG mask, filter, opacity participate in EffectPaintPropertyNode	✓
viewBox → viewport mapping on LayoutSVGRoot becomes a TransformPaintPropertyNode	✓

The "CompositeAfterPaint" architecture is fully on for SVG. SVG paint records and property trees flow through the same commit path as HTML. See ../property-trees.md.

Animations

Subsystem	Status
CSS animations on SVG	Stable — uses standard core/animation/
Web Animations API on SVG	Stable — same engine
SMIL deprecation	Reverted (~2016)
SMIL maintenance	Active — core/svg/animation/ receives ongoing fixes
Compositor-thread animation on SVG transform/opacity	Supported but uncommon (most SVG content lacks its own cc::Layer)

In 2015 Google announced an intent to remove SMIL in favor of CSS / Web Animations. The deprecation was suspended in 2016 because too much content depended on SMIL (no shipping replacement covered sync-base timing and non-CSS attributes like points, d, viewBox). SMIL remains supported indefinitely. See animation-and-smil.md.

Skia integration

Subsystem	Status
Path rasterization via Skia	Stable — cc::PaintRecord → SkCanvas → Skia GPU/CPU backend
Skia GPU backend	Mixed — Ganesh (legacy GL/Vk/Metal) and Graphite (newer Vk/Metal/Dawn) coexist; Graphite is opt-in per platform
Skia's own modules/svg/ (SkSVGDOM)	Unused by Blink — Blink has its own complete SVG implementation
Skia's modules/skottie/ (Lottie player)	Used by cc::PaintSkottie for browser UI animations only — not for web SVG content

Blink does not consume Skia's SVG module. SkSVG is a standalone renderer designed for embedders who need to display an SVG without browser machinery; it cannot integrate with Blink's DOM, CSS, animations, JS bindings, accessibility, or hit-testing.

DOM and bindings

Subsystem	Status
SVGAnimatedProperty<T> (baseVal/animVal)	Stable
Tear-off types (SVGLengthTearOff, etc.)	Stable
Shadow DOM for <use>	Stable (closed shadow root, UA-managed)
<foreignObject> HTML descendants	Stable — use full Blink HTML pipeline

See animated-properties-idl.md for the SVGAnimatedProperty and tear-off mechanisms in detail.

Hit-testing and accessibility

Subsystem	Status
SVG hit-test (path-based)	Stable — see hit-testing.md
pointer-events SVG-specific values (bounding-box, visiblePainted, ...)	Stable
AX tree integration	Stable — uses standard AXNodeObject with SVG branches; no dedicated AXSVG* classes — see accessibility.md

In-flight work

These are areas of active development worth tracking:

• Skia Graphite rollout. Default GPU backend transition from Ganesh to Graphite, per platform. SVG rendering output is unchanged but the underlying Skia GPU pipeline may differ.
• <filter> performance. Filter rendering forces offscreen rasterization and a separate EffectPaintPropertyNode. No published initiative to fast-path simple filters on the compositor.
• CSS d property. The d attribute as a CSS property (animatable via @keyframes) is supported; cross-engine consistency continues to evolve.

Recently completed

• LayoutNG migration for SVG <text> (multi-year project, completed pre-2024).
• <foreignObject> LayoutNG migration (same window).
• CompositeAfterPaint migration for SVG (~2020), folding SVG into the unified property-tree architecture.

See also

• pipeline.md — current pipeline reflecting all completed migrations.
• ../blink-rendering-pipeline.md — HTML side, including LayoutNG status.
• ../property-trees.md — the CompositeAfterPaint property-tree architecture SVG fully uses.