Parsing         Style             Layout                Paint               Composite
───────         ─────             ──────                ─────               ─────────
<svg …>  ──▶   CSS cascade  ──▶  LayoutSVGRoot    ──▶  SVGRootPainter  ──▶ cc::PaintRecord
  │             on SVGElements    │                     │                   │
  │             + presentation    ├── LayoutSVG         ├── SVGContainer    ├── property trees
  │             attributes         ├── Container         ├── Painter         │   (transform/
  │             aliased to CSS    ├── LayoutSVGShape    ├── SVGShape        │    effect/clip)
  │                                ├── LayoutSVGText     ├── Painter         │
  │                                └── …                 └── …               └── RenderSurfaces
  ▼                                 ▲                     ▲                      for filter/mask
SVGElement tree                     │                     │
                        SVG resources resolved         paint servers resolved
                        (clipPath, mask, filter,      via SVGResources::GetClient
                         marker, pattern, gradient)   → shader on PaintFlags

// third_party/blink/renderer/core/svg/svg_animated_length.h
class SVGAnimatedLength : public ScriptWrappable,
                          public SVGAnimatedProperty<SVGLength> {
 public:
  SVGAnimatedLength(SVGElement* context_element,
                    const QualifiedName& attribute_name,
                    SVGLengthMode mode,
                    SVGLength::Initial initial_value,
                    CSSPropertyID css_property_id = CSSPropertyID::kInvalid);
  const CSSValue* CssValue() const final;   // bridges SVG value → CSS cascade
};

LayoutObject
├── LayoutSVGRoot                  extends LayoutReplaced; CSS box ↔ SVG viewport
│   └── (SVG subtree below)
├── LayoutSVGModelObject           abstract base for SVG content
│   ├── LayoutSVGContainer         <g>, <symbol> — groups children
│   │   ├── LayoutSVGTransformableContainer  <g transform=…>
│   │   ├── LayoutSVGViewportContainer       nested <svg>
│   │   ├── LayoutSVGHiddenContainer         <defs>, <clipPath>, <mask>, <filter>, <marker>
│   │   │   └── LayoutSVGResourceContainer   base for all resource containers
│   │   │       ├── LayoutSVGResourcePaintServer    abstract
│   │   │       │   ├── LayoutSVGResourcePattern
│   │   │       │   └── LayoutSVGResourceGradient   (linear + radial concrete)
│   │   │       ├── LayoutSVGResourceClipper
│   │   │       ├── LayoutSVGResourceMasker
│   │   │       ├── LayoutSVGResourceFilter
│   │   │       └── LayoutSVGResourceMarker
│   │   └── …
│   ├── LayoutSVGShape             <path>, <rect>, <circle>, <ellipse>, <line>, <polygon>, <polyline>
│   │   └── LayoutSVGPath          specialization where path can be complex
│   ├── LayoutSVGImage             <image>
│   └── LayoutSVGForeignObject     <foreignObject> — bridges back to HTML layout
└── LayoutSVGText                  <text> — extends LayoutSVGBlock (reuses LayoutNG inline layout)
    └── LayoutSVGInline            <tspan>, <textPath>
        └── LayoutSVGInlineText    text runs

// third_party/blink/renderer/core/paint/svg_shape_painter.cc
void SVGShapePainter::Paint(const PaintInfo& paint_info) {
  if (paint_info.phase != PaintPhase::kForeground ||
      layout_svg_shape_.IsShapeEmpty())
    return;

  // cull-rect skip
  if (SVGModelObjectPainter::CanUseCullRect(layout_svg_shape_.StyleRef())) {
    if (!paint_info.GetCullRect().IntersectsTransformed(
            layout_svg_shape_.LocalSVGTransform(),
            layout_svg_shape_.VisualRectInLocalSVGCoordinates()))
      return;
  }

  ScopedSVGTransformState transform_state(paint_info, layout_svg_shape_);
  ScopedSVGPaintState paint_state(layout_svg_shape_, …);
  if (!DrawingRecorder::UseCachedDrawingIfPossible(…)) {
    SVGDrawingRecorder recorder(…);
    PaintShape(content_paint_info);   // fill → stroke → markers
  }
}