cc::LayerTreeHostImpl (Input Handler & Scroll Logic)
Blink28623 Syys 2025

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 scroll state of all scroll nodes (via the ScrollTree) and determines when a scroll has hit the extent of an element. Currently, this is where overscroll is detected and reported – but only for the root/viewport. For example, the InputHandler sets did_overscroll_root in the scroll result when the root scroll node reaches its boundary , triggering the elastic effect on the root. To support elastic overscroll on non-root elements, this logic in LayerTreeHostImpl (and its ScrollTree/ScrollNode handling) needs to be generalized: it must detect overscroll on any scrollable node and initiate the overscroll animation (via the helper/controller) for that node instead of chaining upward. Understanding LayerTreeHostImpl and how it yields overscroll information (e.g. populating InputHandlerScrollResult.unused_scroll_delta, accumulated overscroll, and overscroll_behavior flags ) is key, as changes here will route overscroll into the ElasticOverscrollController for the right element rather than exclusively the root.

Jaksot(408)

Scroll-Driven Animations Architecture in Chromium Compositor

Scroll-Driven Animations Architecture in Chromium Compositor

The source provides an extensive architectural deep dive into the implementation of Scroll-driven Animations (SDA) within the Chromium project, specifically focusing on the Blink rendering engine and ...

20 Marras 202539min

Blink's Stacking Contexts and Rendering Pipeline

Blink's Stacking Contexts and Rendering Pipeline

The source provides a highly technical and comprehensive overview of CSS stacking contexts and their implementation within Blink, Chrome's rendering engine. It explains the conceptual role of a stacki...

20 Marras 202550min

Fragmentation in Blink LayoutNG

Fragmentation in Blink LayoutNG

The source provides a comprehensive overview of content fragmentation within the Blink rendering engine, focusing heavily on the transition from the legacy engine to the modern LayoutNG architecture. ...

19 Marras 202550min

Kitty Clipboard Integration Over SSH and Tmux

Kitty Clipboard Integration Over SSH and Tmux

The sources provide a detailed technical guide focused on achieving seamless copy-paste functionality between a local Kitty terminal on macOS and a remote Linux session, especially over SSH. The text ...

19 Marras 202523min

View Transition Deep Dive: Lifecycle and Implementation

View Transition Deep Dive: Lifecycle and Implementation

The sources provide a detailed technical examination of the lifecycle of a View Transition in the Chromium browser engine, outlining the complex coordination across various subsystems like Blink, the ...

19 Marras 202531min

LayerTreeHost Core Lifecycle and Commit Methods

LayerTreeHost Core Lifecycle and Commit Methods

The provided text comprises extensive documentation of the LayerTreeHost class, a foundational component in a compositing system (likely Chromium's cc layer). It thoroughly details the object's lifecy...

18 Marras 202543min

Layer Tree Host Impl: Core Compositor Pipeline

Layer Tree Host Impl: Core Compositor Pipeline

The sources provide detailed excerpts from the C++ implementation of the LayerTreeHostImpl class, a fundamental component of the Chromium compositor that manages rendering operations and state on the ...

17 Marras 202542min

cc Elastic Overscroll Architecture Deep Dive

cc Elastic Overscroll Architecture Deep Dive

The source provides an architectural overview of how elastic overscroll (the "rubber-banding" effect) is implemented within the Chromium Compositor (CC) for both the main viewport and individual scrol...

16 Marras 202533min