Blink and Compositor Stacking Contexts

These sources provide an extensive technical explanation of how CSS stacking contexts are implemented within the Chromium rendering engine, focusing on the collaboration between the Blink renderer and the cc compositor. The process begins in Blink, where elements triggering a stacking context (via properties like opacity or z-index) are identified, leading to the creation of internal structures like PaintLayer and EffectPaintPropertyNode to manage z-ordering. Blink then produces a PaintArtifact consisting of drawing commands grouped into paint chunks, each linked to a specific set of property nodes that define the context's position, clipping, and effects. This artifact is passed to the cc compositor, which converts the Blink properties into its own PropertyTrees (especially the EffectNode), using this data to decide which stacking contexts require an isolated drawing buffer, known as a RenderSurfaceImpl, for final GPU compositing and accurate visual blending. Ultimately, Blink determines what is painted and ordered, and cc determines how to composite those results efficiently.