How to Achieve 60 fpsHW Rendering in WebKit for Android

Xijun Chen

2

Agenda

• Overview of rendering in Android WebKit

• Key process of rendering and bottlenecks

• Break bottlenecks• Details of HW rendering

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Overview of rendering (flattened)

DOM Tree(Render Object Tree)

Render Layer Tree

Layout Painting

Screen

RasterizationContent

Web Contents

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rendering bottleneck

Reasonscroll & zoom

(viewport change)

animation

content change

ImpactRasterization

Painting

Layout

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Things we can do

• Reduce work• Avoid duplicate work (cache)• Avoid useless work (only work for visible

area)

• Parallelization• Bring complicate things to extra thread• Bring things to other graphics devices

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Layers for cache

• Render Layer• Avoid layout• Separate the render objects to diff layer

• Graphics Layer (Layer Android)• Avoid painting• Merge render layers by graphic property

• Tile Grids• Avoid rasterization• Merge and raster android layers to Surfaces

with tile grids in it.• Composite and display Surface using GPU

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Overview of rendering (composited)

DOM Tree(Render Object Tree)

Render Layer TreeDisplay Tree

(LayerAndroid Tree)

Layout Painting

Screen

Rasterization (SW)

Raste

rizati

on (H

W)

Tile Grid

Display (HW)

(Ren

derin

g thr

ead)

(GPU)

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HW Rendering Structure

Drawing Collection

Painting Collection

Queued Collection

SurfaceCollectionManager Surfaces

SurfaceCollection

Surface Backing

Display Layers

Surface

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HW Rendering Structure

Front TileGrid

Back TileGrid

Low Res TileGrid

SurfaceBacking

(0, 0) (0, 1)

(1, 0) (1, 1)

(2, 0) (2, 1)

TileGrid

TileGrid

ImageTexture

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HW Rendering Structure

Front Texture

Back Texture

Tile Tile Texture

• TextureInfo• Size

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HW Rendering Process

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Some code – SurfaceCollectionManager::drawGL

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Some code - SurfaceBacking::prepareGL

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Some code - PaintTileOperation

TileGrid::prepareTile

Use painter to paint tile.The painter is either Surface or ImageTexture

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Some code - Tile

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Some code – Interact with GLTransferQueue::updateDirtyTiles

TileTexture::drawGL

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Q & AThanks!