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)

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

blink::EventHandler (Blink core input handling)

blink::EventHandler (Blink core input handling)

Scroll chain builder and overscroll chaining logic. Blink’s EventHandler is responsible for building the scroll chain (the sequence of nested scrollable ancestors) when the user scrolls an element . I...

23 Syys 202526min

blink::ElasticOverscrollController

blink::ElasticOverscrollController

Overscroll orchestration and animation. This Blink-side controller manages the rubber-banding (elastic stretch and rebound) effect when a scrollable area is overscrolled. It observes gesture scroll ev...

23 Syys 202526min

viz::Surface / SurfaceAggregator

viz::Surface / SurfaceAggregator

Receives frames from one or more surfaces (main page and OOPIFs), aggregates them into a single display frame.

23 Syys 202535min

viz::CompositorFrameSink (client side)

viz::CompositorFrameSink (client side)

The submission interface used by cc to hand the frame to viz.

23 Syys 202531min