The source provides an extensive technical comparison of the Paint Property Trees (PPTs) used in Chrome's Blink rendering engine and the corresponding Compositor Property Trees (CC) utilized by the compositor thread. These hierarchical data structures manage four key visual domains—Transforms, Clips, Effects, and Scroll states—to correctly model complex web rendering features like scrolling and 3D transforms. While Blink’s PPTs are built during the pre-paint phase on the main thread to ensure geometric consistency for painting, the CC trees are used on the compositor thread to drive rasterization, input handling, and smooth animations. The document details how the two sets of trees are synchronized during the commit phase and how they enable critical performance features like threaded scrolling and composite-after-paint (SPv2), despite the inherent complexity of maintaining two separate data models.
