ASSIGNED 173354
[Mac] Don't use the scrolling tree to handle wheel events when it contains transforms that are not axis-aligned
https://bugs.webkit.org/show_bug.cgi?id=173354
Summary [Mac] Don't use the scrolling tree to handle wheel events when it contains tr...
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
Patch (13.55 KB, patch)
2018-11-22 12:52 PST, Frédéric Wang (:fredw)
no flags
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
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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