cc::LayerImpl: Compositor Layer Deep Dive
Blink2861 Marras 2025

cc::LayerImpl: Compositor Layer Deep Dive

The sources provide an exhaustive technical explanation of the cc::LayerImpl class, which is the core representation of a visual element within Chromium's multi-threaded rendering pipeline. These layers exist exclusively on the compositor thread and are created or updated during the commit process from the main thread, operating in a layer list mode that leverages four types of property trees (Transform, Clip, Effect, Scroll) to manage hierarchical relationships and properties instead of traditional parent-child pointers. The layer objects are crucial for the performance optimization of drawing frames, as they store geometry, manage input regions for hit testing, and are instrumental in the asynchronous tiling and rasterization system (especially through PictureLayerImpl) and the three-tree model (Active, Pending, Recycle) used for frame staging and reuse. Ultimately, each layer's state is used in the quad generation step to produce a viz::CompositorFrame for the display compositor.


Jaksot(397)

blink::PaintArtifactCompositor

blink::PaintArtifactCompositor

Decides what needs to be composited and prepares the main‑thread representation to feed cc (layers if needed, scrollbar compositing, etc.).

22 Syys 202542min

blink::PaintArtifact

blink::PaintArtifact

The immutable package of paint chunks + display items for this frame, used to drive compositing without re‑painting.

21 Syys 202536min

blink::TransformPaintPropertyNode / ClipPaintPropertyNode / EffectPaintPropertyNode / ScrollPaintPropertyNode

blink::TransformPaintPropertyNode / ClipPaintPropertyNode / EffectPaintPropertyNode / ScrollPaintPropertyNode

The paint property trees captured during painting (transform, clip, effect/opacity, scroll offset) that define visual & coordinate‑space state.

21 Syys 202541min

blink::PaintController

blink::PaintController

Records drawing into a DisplayItemList, segmenting it into PaintChunks keyed by property‑tree state. (Output: a PaintArtifact.)

21 Syys 202533min

blink::LayoutView (root of the layout tree)

blink::LayoutView (root of the layout tree)

Computes geometry for boxes when layout is dirty.

21 Syys 202539min

blink::StyleEngine / style resolver

blink::StyleEngine / style resolver

Recalculates computed styles that changed since last frame (if any).

21 Syys 202542min

blink::Page → blink::LocalFrame / LocalFrameView

blink::Page → blink::LocalFrame / LocalFrameView

The document’s frame & viewport; LocalFrameView is the scrollable root that triggers layout/paint when needed. provided source outlines the fundamental components of the Blink rendering engine, specif...

21 Syys 202539min

blink::WebViewImpl

blink::WebViewImpl

The source text provides an in-depth explanation of the blink::WebViewImpl class within Chromium's Blink rendering engine, characterizing it as the central control point on the renderer's main thread ...

20 Syys 202539min