Bug 218857 – Use native animations for scroll-behavior:smooth on Mac

• Component: Scrolling
• Status: RESOLVED INVALID

[cathiechen]

Try to use the native scroll animation of Mac (scrolling momentum) for smooth scroll.

[Radar WebKit Bug Importer]

<rdar://problem/71591918>

[Martin Robinson]

Created attachment 432463 [details]
Patch

[Martin Robinson]

Created attachment 432581 [details]
Patch

[cathiechen]

Comment on attachment 432581 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=432581&action=review

> Source/WebCore/platform/ScrollAnimator.cpp:-125
> -    m_scrollAnimation->setCurrentPosition(adjustedPosition);

I wonder would this change affect the platform still using m_scrollAnimation?

> Source/WebCore/platform/ScrollView.cpp:-540
> -    setScrollBehaviorStatus(ScrollBehaviorStatus::NotInAnimation);

Looks like we can also remove this in RenderLayerScrollableArea::scrollToOffset()?

[Martin Robinson]

Created attachment 432772 [details]
Patch

[Martin Robinson]

(In reply to cathiechen from comment #4)

Thanks for taking a look at this!

> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=432581&action=review
> 
> > Source/WebCore/platform/ScrollAnimator.cpp:-125
> > -    m_scrollAnimation->setCurrentPosition(adjustedPosition);
> 
> I wonder would this change affect the platform still using m_scrollAnimation?

I don't think this will, because setCurrentPosition is always called before starting a new animation with m_scrollAnimation.

> > Source/WebCore/platform/ScrollView.cpp:-540
> > -    setScrollBehaviorStatus(ScrollBehaviorStatus::NotInAnimation);
> 
> Looks like we can also remove this in
> RenderLayerScrollableArea::scrollToOffset()?

Nice catch! I thought I had gotten all of these, but I missed one.

I've uploaded a new version of the change.

[Martin Robinson]

Created attachment 432928 [details]
Patch

[Martin Robinson]

Created attachment 432931 [details]
Patch

[Martin Robinson]

Now that ScrollAnimator and ScrollAnimatorMac use the same smooth animation, this change is no longer valid.

See: https://bugs.webkit.org/show_bug.cgi?id=230445

[Simon Fraser (smfr)]

We still want to run smooth scrolling animations in the UI process on iOS, but we can do that via a separate bug.

[Martin Robinson]

(In reply to Simon Fraser (smfr) from comment #10)
> We still want to run smooth scrolling animations in the UI process on iOS,
> but we can do that via a separate bug.

That's right. If I'm not mistaken it's tracked by: https://bugs.webkit.org/show_bug.cgi?id=204936.