Chrome RenderingNG: Paint Artifact and Compositor Architecture

source provides an extensive, lecture-style examination of Chrome’s RenderingNG pipeline, specifically focusing on the roles of the PaintArtifact and the PaintArtifactCompositor. The text explains that the modern system uses Composite After Paint (CAP), where the paint stage first generates a PaintArtifact—an immutable object containing drawing commands grouped into paint chunks based on shared visual properties (property tree state). Subsequently, the PaintArtifactCompositor processes this artifact using a layerization algorithm to efficiently convert the paint chunks into GPU layers (cc::Layer objects). Crucially, this separation allows for direct property updates on the compositor thread for actions like scrolling and animations, which ensures smoothness without requiring main thread repainting.