Chromium Compositor's CalculateDrawProperties: Scrolling and Overscroll
Blink2863 Loka 2025

Chromium Compositor's CalculateDrawProperties: Scrolling and Overscroll

The sources provide an extremely detailed, line-by-line breakdown of the Chromium compositor function CalculateDrawProperties, explaining how it prepares the active layer tree for rendering. A primary focus is on how scrolling and elastic overscroll are handled by updating property trees (transform, clip, and effect) to reflect user interaction. Specifically, the function prioritizes applying SyncedProperties, such as the page scale factor (zoom) and the elastic overscroll vector (the bounce effect), ensuring consistency across layer trees before property recomputation. The application of overscroll is platform-dependent, utilizing stretching on Android versus simple translation on non-Android platforms, and these effects are injected into a dedicated transform node that propagates the visual change to all descendant layers. Finally, the function determines visible layers, computes their final draw properties, and assembles the render surface list that the compositor will use to issue drawing commands.


Jaksot(396)

Intersection Observer

Intersection Observer

The sources provide an in-depth explanation of the Intersection Observer API within the Blink rendering engine, focusing on its architecture and implementation to improve web performance. The initial ...

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Chrome Compositor Animation Architecture (cc)

Chrome Compositor Animation Architecture (cc)

The sources provide an extensive architectural overview of the Chrome Compositor Animation (cc) subsystem, which is responsible for executing visual animations like transforms and opacity changes effi...

15 Loka 202541min

Blink's Graph Data Structures and Traversals

Blink's Graph Data Structures and Traversals

The text provides an extensive overview of the graph-structured data structures used within Blink, Chromium's rendering engine, detailing how web content is processed from initial input to final displ...

13 Loka 202539min

blink::PropertyTreeManager

blink::PropertyTreeManager

bridges Blink property trees → cc property trees. Given Blink’s Transform/Clip/Effect/Scroll nodes (from paint property trees), this class creates/updates the cc counterparts (cc::TransformNode, cc::C...

10 Loka 202546min

blink::PaintArtifactCompositor

blink::PaintArtifactCompositor

turns chunks into compositor layers & updates cc property trees. Consumes the new PaintArtifact and does the layerization and property‑tree updates required for compositor draw. It supports fast paths...

10 Loka 202529min

blink::PaintChunk and blink::DisplayItemList

blink::PaintChunk and blink::DisplayItemList

grouping and content. PaintChunk: groups sequential display items that share the same property‑tree state and cull/visibility; it’s the unit we layerize and invalidate.DisplayItemList: the recorded Sk...

10 Loka 202537min

blink::PaintArtifact

blink::PaintArtifact

the immutable “what to draw” package for this frame. A PaintArtifact is the product of Blink painting: a DisplayItemList plus an ordered vector of PaintChunks. It is immutable post‑creation and design...

10 Loka 202531min

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