Clip Nodes in the Blink and Chromium Compositor

The provided text explains how Chromium’s Blink engine and the compositor utilize clip nodes within property trees to manage page geometry and visual masking. These nodes define specific regions where content remains visible, specifically handling CSS overflow, clip-paths, and border-radius through a hierarchical structure. The system differentiates between main-thread clipping, which is flexible but CPU-intensive, and compositor-thread clipping, which leverages the GPU for higher performance during scrolling and animations. By separating clipping into dedicated clip trees, the engine ensures that visual restrictions are applied efficiently without redundant calculations. This architectural approach also facilitates precise hit testing and optimized rasterization by identifying which parts of an element are interactive or visible to the user. Overall, the sources detail the lifecycle of clipping data as it moves from initial layout through pre-paint to final GPU compositing.