Compositor-Thread Scrolling – CC Mechanics and Property Trees
Blink28611 Marras 2025

Compositor-Thread Scrolling – CC Mechanics and Property Trees

The source provides an extensive technical overview of Chrome’s Compositor-Thread Scrolling architecture, explaining how modern web rendering achieves smooth, low-latency scrolling by handling most scroll events off the main thread. This process relies on key data structures called property trees—specifically the ScrollTree, TransformTree, and ClipTree—which manage scroll offsets, geometric transformations, and viewport boundaries, respectively. The LayerTreeHostImpl orchestrates the sequence: it receives input events via the InputHandlerProxy, determines the scroll target via hit testing, updates the ScrollNode's offset, and leverages the TransformTree to translate content on the GPU without needing the main thread for layout or style updates. Additionally, the system details how it manages advanced features like scroll animations (flings), scroll snapping, platform-specific overscroll effects (elasticity/glow), and fallbacks to main-thread scrolling when necessary, ensuring the continuous flow of rendered frames.


Jaksot(417)

cc::CommitState

cc::CommitState

The provided source offers an extensive architectural analysis of Chromium’s cc::CommitState struct, detailing its critical function as the intermediary data structure that facilitates communication b...

25 Syys 202540min

Blink and Compositor Stacking Contexts

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...

25 Syys 202538min

Chromium Architecture: Input, Synchronization, and Animation Pipelines

Chromium Architecture: Input, Synchronization, and Animation Pipelines

These sources provide an extensive architectural overview of the core C++ classes that implement Chromium's input handling, synchronization, and animation systems. The documents detail the multi-proce...

25 Syys 202540min

CSS View Transition Pseudo-elements Explained

CSS View Transition Pseudo-elements Explained

These sources provide a detailed, technical explanation of the View Transition API implementation within the Chromium web browser, focusing on how CSS pseudo-elements enable smooth animations. The fir...

24 Syys 202538min

gpu::SkiaOutputSurfaceImplOnGpu / gpu::CommandBuffer

gpu::SkiaOutputSurfaceImplOnGpu / gpu::CommandBuffer

Bridges Skia’s recorded commands to the GPU command buffer; submits and SwapBuffers to present. (Backend: GL/Vulkan/Metal via GPU process.)

23 Syys 202532min

viz::SkiaRenderer

viz::SkiaRenderer

Renderer that turns quads into Skia operations (recording DDLs / drawing to the output surface).

23 Syys 202552min

viz::Display

viz::Display

The display compositor that walks the aggregated render passes and issues draw commands for the final output.

23 Syys 202538min

cc::LayerTreeHostImpl (Input Handler & Scroll Logic)

cc::LayerTreeHostImpl (Input Handler & Scroll Logic)

Scroll processing and overscroll detection in the compositor. The LayerTreeHostImpl in cc implements the compositor-thread InputHandler that processes gesture scroll updates and flings. It manages the...

23 Syys 202527min