Bug 253070 – Fix alignToClosestEdge semantics in ScrollableArea::getRectToExposeForScrollIntoView

• Component: Scrolling
• Status: NEW

[Ahmad Saleem]

Created attachment 465218 [details]
Patch GitHub Desktop Screenshot

Hi Team,

While going through Blink's commit, I came across another where we are failing tests but Chrome Canary 113 is passing them while Firefox Nightly 112 is matching Safari Technology Preview 164.

Test case - https://jsfiddle.net/tzj4kq28/show

Blink Commit - https://chromium.googlesource.com/chromium/blink/+/ae8d18613905f501a3ce9ba83193fe77e920afbf

WebKit Source - https://searchfox.org/wubkat/source/Source/WebCore/platform/ScrollableArea.cpp#857 & https://searchfox.org/wubkat/source/Source/WebCore/platform/ScrollableArea.cpp#899

I have done local merge of this patch but it does not lead to pass on this testcase but it would be good to track and get input whether this is legit bug in WebKit or not.

Just raising for tracking.

Thanks!

[Radar WebKit Bug Importer]

<rdar://problem/106356373>

[Karl Dubost]

I'm not sure. 
Safari and Firefox are behaving the same in these tests.

[Ahmad Saleem]

Created attachment 472492 [details]
Test Case from Blink Issue Tracker

In this attached - at least for me, Chrome Canary 130 and Firefox Nightly 132 are matching and showing 'gray' container while Safari Technology Preview 202 does not.

[Karl Dubost]

Created attachment 472496 [details]
rendering in safari, firefox, chrome

Very interesting.
In Ahmad test case, none of the browsers are behaving the same way.

* Safari aligns on top of the scrolling context
* Firefox aligns the grey square in a way that it is fully visible and so align to the bottom of the scrolling context.
* Chrome aligns in a way that the bottom of the green area is aligned and so it shows  half of the grey box. (so… in between?)