[webkit-changes] [WebKit/WebKit] c3591d: [web-animations] custom properties should support ...

[Antoine Quint]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: c3591d297f097a553bbf668e6096d96fb62e546d
      https://github.com/WebKit/WebKit/commit/c3591d297f097a553bbf668e6096d96fb62e546d
  Author: Antoine Quint <graouts at apple.com>
  Date:   2022-12-15 (Thu, 15 Dec 2022)

  Changed paths:
    M LayoutTests/imported/w3c/web-platform-tests/css/css-properties-values-api/animation/custom-property-animation-length-expected.txt
    M Source/WebCore/animation/CSSPropertyAnimation.cpp
    M Source/WebCore/animation/CSSPropertyBlendingClient.h
    M Source/WebCore/animation/KeyframeEffect.h

  Log Message:
  -----------
  [web-animations] custom properties should support interpolation with a single keyframe
https://bugs.webkit.org/show_bug.cgi?id=249384

Reviewed by Antti Koivisto.

Custom properties can specify an initial value when registered. However, that value is not
available in RenderStyle if the custom property is not provided with an explicit value. This
means that when we added basic support for interpolating custom properties in bug 249312, we
would fail to gather the right values for interpolating as we'd have a null value if the keyframes
did not set explicit values.

We can get to the initial value of a custom property through the custom property registry held
by the document. So we add a new document() method to CSSPropertyBlendingClient such that we may
be able to read from this registry when interpolating from within CSSPropertyAnimation.

Then we add a static method customPropertyValuesForBlending that returns a pair of CSSCustomPropertyValue
pointers containing either the explicit value set for a custom property, or its initial value.

Now we are guaranteed to get the correct values when interpolating.

* LayoutTests/imported/w3c/web-platform-tests/css/css-properties-values-api/animation/custom-property-animation-length-expected.txt:
* Source/WebCore/animation/CSSPropertyAnimation.cpp:
(WebCore::blendCustomProperty):
* Source/WebCore/animation/CSSPropertyBlendingClient.h:
* Source/WebCore/animation/KeyframeEffect.h:

Canonical link: https://commits.webkit.org/257911@main