Blink Compositor Promotion of CSS Animations
Blink2866 Marras 2025

Blink Compositor Promotion of CSS Animations

The technical sources provide an extensive analysis of how the Blink rendering engine (used in Chromium/Chrome) determines whether a CSS animation can be executed on the compositor thread instead of the main thread to improve performance and achieve smooth frame rates. This process involves a complex pipeline, beginning with style calculation and proceeding through layout and layer assignment, where an element must be assigned a composited layer and corresponding property tree nodes to be eligible for acceleration. The critical decision is made by the function CheckCanStartAnimationOnCompositor(), which only permits animations on a limited set of properties—primarily transform, opacity, filter, and backdrop-filter—while rejecting anything affecting layout or requiring frame-by-frame repainting. If accelerated, the animation’s keyframes are converted into CompositorAnimation objects and run by the GPU-assisted compositor, allowing the main thread to remain free for other tasks.

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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

SyncedProperty: Cross-Thread Compositor Synchronization

SyncedProperty: Cross-Thread Compositor Synchronization

The source provides a detailed technical exploration of SyncedProperty, a critical synchronization mechanism within Chromium's compositor (cc) designed to manage properties updated concurrently on bot...

16 Marras 202532min

Blink's PendingLayer: Bridge Between Paint and Compositor

Blink's PendingLayer: Bridge Between Paint and Compositor

The document provides an extensive technical overview of the PendingLayer class, a critical internal component within Blink’s Composite After Paint (CAP) architecture. PendingLayer acts as a liaison, ...

15 Marras 202530min

RasterSource and Rendering Pipeline

RasterSource and Rendering Pipeline

The source provides an extensive technical overview of the RasterSource concept within the Chromium browser's rendering pipeline. This component serves as a crucial, immutable, and thread-safe contain...

14 Marras 202532min

Containing Blocks in CSS and Blink Layout

Containing Blocks in CSS and Blink Layout

The source provides a highly technical, in-depth analysis of the concept of containing blocks in CSS layout, explaining how these invisible boundaries determine the sizing and positioning of elements,...

13 Marras 202554min

Chromium Compositor Scroll and Gesture Event Handling

Chromium Compositor Scroll and Gesture Event Handling

The source text explains how Chromium handles gesture and scroll events within its input pipeline, particularly focusing on the interaction between the Blink/UI thread and the compositor thread. It de...

12 Marras 202536min

Chrome Finch Field Trial Configuration Deep Dive

Chrome Finch Field Trial Configuration Deep Dive

The source provides an extensive explanation of Chrome Finch Field Trials, which is the framework Chrome uses for running experiments and feature rollouts without requiring a full browser update. Spec...

11 Marras 202541min

Advanced Scrolling Scenarios – Fixed Elements, Sticky Positioning, and Lifecycle Coordination

Advanced Scrolling Scenarios – Fixed Elements, Sticky Positioning, and Lifecycle Coordination

The source provides an extensive technical explanation of how the Chrome rendering engine, Blink, and its Compositor implement advanced CSS scrolling features like position: fixed and position: sticky...

11 Marras 202551min