Bug 235788

Summary: css/css-backgrounds/animations/border-image-source-interpolation.html has failures
Product: WebKit Reporter: Antoine Quint <graouts>
Component: AnimationsAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: dino, graouts, karlcow, nmouchtaris, webkit-bug-importer
Priority: P2 Keywords: BrowserCompat, InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 232087    

Description Antoine Quint 2022-01-28 07:36:02 PST
css/css-backgrounds/animations/border-image-source-interpolation.html has 50 failures, we need to investigate and fix them.
Comment 1 Radar WebKit Bug Importer 2022-02-04 07:36:19 PST
<rdar://problem/88488364>
Comment 2 Karl Dubost 2023-12-13 22:30:42 PST
Antoine,

These failures are weird.
They happen mostly when

"border-image-source" is set 
* from "inherit" 
* to something else

and the window.getComputedStyle value returns a surprising "cross-fade()"

For example:

CSS Transitions and CSS Animations
<border-image-source> 
from [inherit] 
to [url(http://wpt.live/support/orange_color.png)] at (-0.3) 
should be [url(http://wpt.live/support/orange_color.png)]

but it returns 
cross-fade(
  url(http://wpt.live/support/green.png), 
  url(http://wpt.live/support/orange_color.png), 
  -0.3
  )

Why the cross-fade() ?
This happens only when the starting value is inherit and different from 0


For inherit and 0, it has a different error
expected: url(http://wpt.live/support/orange_color.png)
actual:   url(http://wpt.live/support/green.png)

For inherit and 1, they PASS

Web Animations seem to be mostly working apart of a couple of things.


CSS Animations tests
from image to image mostly fail in the intermediate steps (so except for 0 and 1 which is a PASS).
Comment 3 Antoine Quint 2023-12-14 13:59:20 PST
This is because we treat most of the image types in CSS as animatable when they are not. The `cross-fade()` value is a representation of blending two images. The issue is that WebKit feels those specs should be updated to make those properties animatable.