cc Transform and Scroll Trees
Blink28628 Syys 2025

cc Transform and Scroll Trees

The source text details the architecture of Chromium's compositor, focusing on the tandem operation of two critical data structures: the Transform Tree and the Scroll Tree. The Transform Tree manages visual coordinate space transformations, including CSS transforms and scroll offsets, with each TransformNode calculating its final position relative to its parent using local matrices and the scroll translation. In parallel, the Scroll Tree, composed of ScrollNodes, handles the logical state of scrollable elements, defining constraints like scrollable bounds, allowed directions, and scroll chaining behavior. Crucially, the sources explain that the two trees are linked via a shared ElementId and that while the Scroll Tree determines how a scroll should happen (bounds and policy), the Transform Tree executes the change by holding and applying the live scroll_offset to visually move the layer content, enabling smooth, composite-threaded scrolling.

Jaksot(391)

7 Blink View Transition Discovery and UA Stylesheet Generation

7 Blink View Transition Discovery and UA Stylesheet Generation

This document details how the Blink rendering engine manages the technical lifecycle of View Transitions by coordinating DOM updates with visual animations. Once a developer triggers a transition, the...

27 Tammi 31min

6 Blink and Compositor Handshake in View Transitions

6 Blink and Compositor Handshake in View Transitions

The provided text explains the technical handshake between the Blink rendering engine and the compositor during a web view transition. To ensure visual continuity, the system captures a snapshot of th...

27 Tammi 30min

Evolution of CSS: Working Group Drafts and Processes

Evolution of CSS: Working Group Drafts and Processes

The provided text outlines the operations and standardizing procedures of the W3C CSS Working Group, which manages the evolution of web presentation through a modular specification system. It details ...

27 Tammi 38min

5 View Transition Mechanics: Pre-paint and Snapshot Coordination

5 View Transition Mechanics: Pre-paint and Snapshot Coordination

The provided text explains how the Blink rendering engine manages view transitions by utilizing a stable coordinate space known as the snapshot root. This mechanism ensures that animations remain cons...

27 Tammi 27min

4 Blink View Transition Pseudo-Element Tree and Layout Integration

4 Blink View Transition Pseudo-Element Tree and Layout Integration

The provided text explains how the Blink rendering engine manages View Transitions by generating a temporary pseudo-element subtree to represent page changes. This system acts as an overlay, capturing...

26 Tammi 39min

GEM Modern CSS Scroll Positioning and Visibility Specifications

GEM Modern CSS Scroll Positioning and Visibility Specifications

These sources detail the CSS and DOM specifications that govern how elements are positioned and animated when moved into a user's visible area. The documentation introduces scroll-padding and scroll-m...

25 Tammi 33min

[GENERAL] Modern CSS Scroll Positioning and Visibility Specifications

[GENERAL] Modern CSS Scroll Positioning and Visibility Specifications

These sources collectively define the technical standards for how web browsers handle scrolling and element visibility. The documentation details the CSSOM View Module's specific algorithm for the scr...

25 Tammi 30min

Modern CSS Scroll Positioning and Visibility Specifications

Modern CSS Scroll Positioning and Visibility Specifications

These sources collectively define the technical standards for scroll-into-view behavior within modern CSS specifications, covering how elements are positioned and animated when navigated to or targete...

25 Tammi 38min