1418895 - Very slow mask painting when using an SVG in mask-image

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Markus Stange [:mstange]]

Attachment: testcase

Profile from testcase: https://perfht.ml/2jGMswY

Steps to reproduce:
 1. Enable WebRender and blob-images.
 2. Go to https://qz.com/ .
 3. Notice that painting in the upper part of the page is really slow.


There's an element with mask-image: url(somesvg.svg). When we prepare the WebRender image for the nsDisplayMask, we use a DrawTargetRecording and call nsCSSRendering::PaintStyleImageLayerWithSC. This draws the SVG image into the DrawTargetRecording using mozilla::image::VectorImage::Draw, which draws it as a surface. This causes us to put all the pixels of that surface into the command stream.

Comment 1

[Andrew Osmond [:aosmond] (he/him)]

In a pinch, I can impute imgIContainer::FLAG_BYPASS_SURFACE_CACHE in VectorImage::Draw if the gfxContext::GetDrawTarget is a recording backend. This will cause us to record the commands as expected. In an ideal world we'd probably store SourceSurfaceRecording in the SurfaceCache, and replay that upon the given DrawTargetRecording, but it looks like DrawTargetRecording doesn't actually support that at this time.

Comment 2

[Andrew Osmond [:aosmond] (he/him)]

Attachment: 0001-Bug-1418895-VectorImage-Draw-should-imply-FLAG_BYPAS.patch

Comment 3

[Andrew Osmond [:aosmond] (he/him)]

try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=4edcaf256a4b56056c550295256df893898389bc

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/dee67ed7eb78
VectorImage::Draw should imply FLAG_BYPASS_SURFACE_CACHE for DrawTargetRecording. r=tnikkel

Comment 5

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/dee67ed7eb78

Comment 6

[Markus Stange [:mstange]]

This patch made an amazingly huge difference in the performance of that website!