CSS View Transition Pseudo-elements Explained
Blink28624 Syys 2025

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 first source explains that view transition pseudos (like ::view-transition-old() and ::view-transition-new()) are temporary, browser-synthesized overlays used to capture and animate visual snapshots of elements during state changes. The second, more extensive source describes the low-level C++ classes in the Blink rendering engine and the cc compositor that orchestrate this process, including the DocumentTransition class, which manages the lifecycle, snapshot capture, and pseudo-element creation, and the SurfaceAnimationManager in the Viz component, which handles the final, performant GPU-accelerated animation of the saved frames using specialized layers and directives. Together, the texts map the high-level CSS API to the complex, multi-process architecture of Chromium, explaining how old and new content are matched, isolated on the top layer, and composited for animation.


Jaksot(397)

blink::PaintController

blink::PaintController

builds the display list + paint chunks and manages caching. As painters call into GraphicsContext, they also drive a PaintController which groups drawing into display items and paint chunks (each keye...

10 Loka 202529min

blink::GraphicsContext

blink::GraphicsContext

immediate drawing API that records to a display list. Painters for layout objects use GraphicsContext to “draw”—but in modern Blink those calls get recorded into a display list (PaintRecord) backed by...

10 Loka 202544min

blink::TransformPaintPropertyNode / ClipPaintPropertyNode / EffectPaintPropertyNode / ScrollPaintPropertyNode

blink::TransformPaintPropertyNode / ClipPaintPropertyNode / EffectPaintPropertyNode / ScrollPaintPropertyNode

These are the nodes within those four trees. Every piece of painted content (a “paint chunk”) is associated with a tuple of (Transform, Clip, Effect, Scroll) nodes—its PropertyTreeState. This precisel...

10 Loka 202533min

blink::PaintPropertyTreeBuilder

blink::PaintPropertyTreeBuilder

builds/updates paint property trees.Consumes the layout/fragment data and produces the four paint property trees (Transform, Clip, Effect, Scroll) for the current frame. These trees encode coordinate ...

10 Loka 202547min

blink::PrePaintTreeWalk

blink::PrePaintTreeWalk

cross‑frame pre‑paint traversal. Runs in the InPrePaint lifecycle phase. Walks the entire layout tree starting at the root LocalFrameView, updating paint invalidation state and computing the context n...

10 Loka 202531min

blink::NGPhysicalFragment and friends

blink::NGPhysicalFragment and friends

Layout takes the styled DOM and produces a fragment tree of positioned boxes. In modern Blink this is LayoutNG; the core artifact is NGPhysicalFragment, which stores geometry and is used downstream fo...

10 Loka 202537min

blink::StyleEngine

blink::StyleEngine

style invalidation & resolution (recalc). 
Given DOM/style changes since the last frame, StyleEngine computes updated ComputedStyles, manages active stylesheets/media query state, and marks the right ...

10 Loka 202534min

blink::Document & blink::DocumentLifecycle

blink::Document & blink::DocumentLifecycle

states that gate phases. The document owns the DOM and keeps a DocumentLifecycle state machine that ensures we do things in phase order (style before layout, pre‑paint before paint, etc.). Lifecycle t...

10 Loka 202535min