Bug 173354

Summary: [Mac] Don't use the scrolling tree to handle wheel events when it contains transforms that are not axis-aligned
Product: WebKit Reporter: Frédéric Wang (:fredw) <fred.wang>
Component: FramesAssignee: Nobody <webkit-unassigned>
Status: ASSIGNED    
Severity: Normal CC: fred.wang, rbuis, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Other   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on: 172917    
Bug Blocks: 171667    
Attachments:
Description Flags
Patch
none
Patch none

Frédéric Wang (:fredw)
Reported 2017-06-14 00:59:49 PDT
Extracted from bug 171667. Handling transforms might be a little bit complicated, so we can start by falling back to the slow path.
Attachments
Patch (13.13 KB, patch)
2017-06-14 02:08 PDT, Frédéric Wang (:fredw) 		no flags
DetailsFormatted DiffDiff
Patch (13.55 KB, patch)
2018-11-22 12:52 PST, Frédéric Wang (:fredw) 		no flags
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Frédéric Wang (:fredw)
Comment 1 2017-06-14 02:08:41 PDT
Created attachment 312871 [details] Patch (In reply to Frédéric Wang (:fredw) from comment #30) > Created attachment 311503 [details] > Patch (do not use async scrolling when there are transformed nodes) > > This is an attempt to avoid async scrolling when there are transformed > nodes, but it does not work. I debugged this again and my attempt was actually correct... When there is a transform on the scrolling tree, ScrollingTree::shouldHandleWheelEventSynchronously will return true, tryToHandleWheelEvent will return SendToMainThread and EventDispatcher will thus pass the event to the main thread instead of calling ScrollingTree::handleWheelEvent. However, at the end the the following call stack is executed: ScrollingTree::handleWheelEvent (scrolling thread) ThreadedScrollingTree::handleWheelEvent (scrolling thread) ScrollingCoordinatorMac::handleWheelEvent (main thread) FrameView::wheelEvent (main thread) EventHandlerMac's EventHandler::platformCompleteWheelEvent (main thread) EventHandler::handleWheelEvent (main thread) so the event is still handled by the scrolling thread! @Simon: I commented the guilty part out in FrameView::wheelEvent, so that ScrollableArea::handleWheelEvent is called instead and things work as I expected, but I wonder what would be the proper way to fix that?
Frédéric Wang (:fredw)
Comment 2 2018-11-22 12:52:24 PST
Created attachment 355487 [details] Patch Rebasing...
Radar WebKit Bug Importer
Comment 3 2019-01-29 20:44:42 PST
<rdar://problem/47656477>
Simon Fraser (smfr)
Comment 4 2019-02-21 11:20:56 PST
We'll need this at some point (I am not working on this currently).
Frédéric Wang (:fredw)
Comment 5 2025-07-07 03:20:07 PDT
Unassigning myself since I'm not working on this.
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