1476058 - Optimize away fully-transparent blob images

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement, P2)

Description

[Kartikaya Gupta (email:[e-mail])]

It seems like we often create blob images that are fully transparent. We should stop doing that.

At least one source of such blobs is if you have a XUL image element with a background but nothing else. The XULImage display item returns false from [1] which makes us go down the fallback path which doesn't draw anything.

There might be other sources of blobs. The way I see them is grab a WR capture, and look at the blobs/ folder. If the blob just a bunch of zeros then it's fully transparent.

[1] https://searchfox.org/mozilla-central/rev/b0275bc977ad7fda615ef34b822bba938f2b16fd/layout/xul/nsImageBoxFrame.cpp#555

Comment 1

[Kartikaya Gupta (email:[e-mail])]

https://mozilla.staktrace.com/raw-renderer.html (which will be available whenever github resolves their current issues and rebuilds the site) can be used to render the .raw files. You can usually the width/height info in one of the .ron files.

Comment 2

[Markus Stange [:mstange]]

I think this should be fixed on a case-by-case basis: If a display item is returning false from CreateWebRenderCommands but then doesn't paint anything, that's a good sign that it should have returned true.

Comment 3

[Aria Beingessner [:Gankra]]

Agreed

Comment 4

[Aria Beingessner [:Gankra]]

Attachment: Bug 1476058 - consider no image to be successful for wr.

Review commit: https://reviewboard.mozilla.org/r/259122/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/259122/

Comment 5

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

Comment on attachment 8994581 [details]
Bug 1476058 - consider no image to be successful for wr.

https://reviewboard.mozilla.org/r/259122/#review266320

We may need to make a similar change in nsDisplayImage::CreateWebRenderCommands.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b09ee6fada54
consider no image to be successful for wr. r=aosmond

Comment 7

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/b09ee6fada54