264469 2023-11-08 23:47:30 -0800 Incorrect wheel event behavior with Shadow DOM 2024-01-18 09:02:56 -0800 1 1 1 Unclassified WebKit Scrolling Safari 17 Mac (Apple Silicon) macOS 14 RESOLVED FIXED InRadar P2 Normal --- 148695 1 bretislav simon.fraser nmouchtaris rniwa simon.fraser webkit-bug-importer oldest_to_newest 1991082 0 468530 bretislav 2023-11-08 23:47:30 -0800 Created attachment 468530 safari-wheel-listener-scroll-issue.html One of our customers complained about the inability to scroll the page when over certain elements on the page when using MacBook, Safari and either Trackpad or MagicMouse. Note that the same issue cannot be reproduced with other browsers or when scrolling with a mouse with a physical wheel. For reference, this is the bug on our side: https://github.com/vaadin/web-components/issues/6695 We reduced the issue test case to what is attached in safari-wheel-listener-scroll-issue.html. The DOM structure presented there is a simplification of our app structure, the minimal structure where I was still able to reproduce the issue. Test instructions: 1. Open Safari on Mac and use either Trackpad or MagicMouse for scrolling 2. Open safari-wheel-listener-scroll-issue.html 3. Position the mouse over one of the colored areas and swipe with two fingers in a way that the page should scroll down 4. -> "test-container" element content scrolls 5. Now Position the mouse over the white stripe 6. Swipe the same way Actual behavior: Now the "body" scrolls instead of the "test-container" Expected behavior: I'd expect the "test-container" to scroll as in other browsers, or when scrolling with mouse with physical wheel The weird thing is that the issue is caused just by attaching an *empty* "wheel" event listener to one of the elements in the DOM structure -> comment out line 35, so the event listener is not added, and suddenly, the scroll behavior is different and the "test-container" scrolls even when positioned over the white stripe. I believe that adding an empty event listener anywhere should not change the scrolling behavior of the page, regardless of the DOM structure. Safari Version 17.1 (19616.2.9.11.7) Mac Mini M2 macOS 14.1 (23B74) 1991683 1 ap 2023-11-10 13:35:26 -0800 Adding a wheel event listener changes everything about how scrolling works, as every event now has to hop across processes. What you are describing looks like a bug, however I expect that there will always be performance implications from having event listeners. 1991685 2 simon.fraser 2023-11-10 13:47:36 -0800 Does this reproduce without the Shadow DOM stuff in the test page? 1992438 3 bretislav 2023-11-14 05:44:15 -0800 @Simon No, it cannot be reproduced if I use simple <div> instead of that web-component with a Shadow DOM and <slot> in it. So using the web component in the DOM structure is required to reproduce this issue. In the real use-case, where we noticed the bug, we use much more complicated structure of web components and other elements... however, I was able to narrow down the test case to what is in the attachment. 1993016 4 webkit-bug-importer 2023-11-15 23:48:13 -0800 <rdar://problem/118496293> 2005748 5 simon.fraser 2024-01-17 20:56:41 -0800 This fixes it, but I'm not entirely sure if it's correct: diff --git a/Source/WebCore/page/mac/EventHandlerMac.mm b/Source/WebCore/page/mac/EventHandlerMac.mm index c13fcc320751735a86565b8e3e67f8d9c9984608..97e4eb43530930df997f462d942da55b4dde4404 100644 --- a/Source/WebCore/page/mac/EventHandlerMac.mm +++ b/Source/WebCore/page/mac/EventHandlerMac.mm @@ -800,7 +800,7 @@ static ContainerNode* findEnclosingScrollableContainer(ContainerNode* node, cons { // Find the first node with a valid scrollable area starting with the current // node and traversing its parents (or shadow hosts). - for (ContainerNode* candidate = node; candidate; candidate = candidate->parentOrShadowHostNode()) { + for (auto* candidate = node; candidate; candidate = candidate->parentInComposedTree()) { if (is<HTMLIFrameElement>(*candidate)) continue; 2005751 6 simon.fraser 2024-01-17 21:21:56 -0800 Pull request: https://github.com/WebKit/WebKit/pull/22892 2005865 7 ews-feeder 2024-01-18 09:02:54 -0800 Committed 273181@main (bd33a8e97f27): <https://commits.webkit.org/273181@main> Reviewed commits have been landed. Closing PR #22892 and removing active labels. 468530 2023-11-08 23:47:30 -0800 2023-11-08 23:49:20 -0800 safari-wheel-listener-scroll-issue.html safari-wheel-listener-scroll-issue.html text/html 1953 bretislav PCFET0NUWVBFIGh0bWw+CjxodG1sIGxhbmc9ImVuIj4KPGhlYWQ+CiAgICA8bWV0YSBjaGFyc2V0 PSJVVEYtOCIvPgogICAgPG1ldGEgaHR0cC1lcXVpdj0iWC1VQS1Db21wYXRpYmxlIiBjb250ZW50 PSJJRT1lZGdlIi8+CiAgICA8bWV0YSBuYW1lPSJ2aWV3cG9ydCIgY29udGVudD0id2lkdGg9ZGV2 aWNlLXdpZHRoLCBpbml0aWFsLXNjYWxlPTEuMCIvPgogICAgPHRpdGxlPlNhZmFyaSB3aGVlIGxp c3RlbmVyIHNjcm9sbCBpc3N1ZTwvdGl0bGU+CjwvaGVhZD4KPGJvZHk+Cgo8ZGl2IGlkPSJvdXRs ZXQiIHN0eWxlPSJoZWlnaHQ6IDEwMHZoOyB3aWR0aDogMTAwJTsgbWFyZ2luLWJvdHRvbTogNTBw eDsiPgogICAgPHRlc3QtY29udGFpbmVyPgogICAgICAgIDxkaXYgc3R5bGU9ImJhY2tncm91bmQt Y29sb3I6IGdyZWVuOyBoZWlnaHQ6IDMwMHB4OyB3aWR0aDogMTAwJTsgY29sb3I6IHdoaXRlIj4K ICAgICAgICAgICAgUG9zaXRpb24geW91ciBtb3VzZSBvdmVyIHRoaXMgdGV4dCBhbmQgdHJ5IHRv IHN3aXBlIGRvd24gd2l0aAogICAgICAgICAgICB0b3VjaHBhZCBvbiBNYWMgaW4gU2FmYXJpIHRv IHNjcm9sbCBkb3duPGJyPgogICAgICAgICAgICAtPiB0aGUgInRlc3QtY29udGFpbmVyIiBzY3Jv bGxzIGFzIGV4cGVjdGVkCiAgICAgICAgPC9kaXY+CiAgICAgICAgPGRpdiBpZD0iY29udGVudCIg c3R5bGU9ImhlaWdodDogMTUwcHgiPgogICAgICAgICAgICBQb3NpdGlvbiB5b3VyIG1vdXNlIG92 ZXIgdGhpcyB0ZXh0IGFuZCB0cnkgdG8gc3dpcGUgZG93biB3aXRoCiAgICAgICAgICAgIHRvdWNo cGFkIG9uIE1hYyBpbiBTYWZhcmkgdG8gc2Nyb2xsIGRvd248YnI+CiAgICAgICAgICAgIC0+IDxi PnRoZSAiYm9keSIgc2Nyb2xscyBpbnN0ZWFkIG9mIHRoZSAidGVzdC1jb250YWluZXIiIChsb29r IGF0IHRoZSBzY3JvbGxiYXJzIG9uIHJpZ2h0KSAtPiB0aGF0IGlzCiAgICAgICAgICAgIHVuZXhw ZWN0ZWQgYW5kIGRpZmZlcnMgZnJvbSBvdGhlciBicm93c2VyczwvYj48YnI+CiAgICAgICAgICAg IC0+IDxiPnJlbW92ZSB0aGUgZW1wdHkgJ3doZWVsJyBldmVudCBsaXN0ZW5lciBmcm9tIHRoZSAn I2NvbnRlbnQnCiAgICAgICAgICAgIGVsZW1lbnQKICAgICAgICAgICAgLT4gc3VkZGVubHkgdGhl IHNjcm9sbGluZyBiZWhhdmlvciBpcyBjb3JyZWN0IDwvYj48YnI+CiAgICAgICAgPC9kaXY+CiAg ICAgICAgPGRpdiBzdHlsZT0iYmFja2dyb3VuZC1jb2xvcjogcmVkOyBoZWlnaHQ6IDIwMDBweDsg d2lkdGg6IDEwMCUiPjwvZGl2PgogICAgPC90ZXN0LWNvbnRhaW5lcj4KPC9kaXY+Cgo8c2NyaXB0 IHR5cGU9Im1vZHVsZSI+CiAgICBjb25zdCBjb250ZW50ID0gZG9jdW1lbnQucXVlcnlTZWxlY3Rv cigiI2NvbnRlbnQiKTsKCiAgICAvLyByZW1vdmUgdGhpcyBsaW5lIHRvIHNlZSB0aGF0IHRoZSBz Y3JvbGxpbmcgYmVoYXZpb3Igd2hlbiB5b3UgYXJlIG92ZXIgI2NvbnRlbnQgY2hhbmdlcwogICAg Y29udGVudC5hZGRFdmVudExpc3RlbmVyKCd3aGVlbCcsICgpID0+IHt9KTsKCiAgICBjbGFzcyBU ZXN0Q29udGFpbmVyIGV4dGVuZHMgSFRNTEVsZW1lbnQgewogICAgICAgIGNvbm5lY3RlZENhbGxi YWNrKCkgewogICAgICAgICAgICBjb25zdCBzaGFkb3cgPSB0aGlzLmF0dGFjaFNoYWRvdyh7bW9k ZTogJ29wZW4nfSk7CiAgICAgICAgICAgIHNoYWRvdy5pbm5lckhUTUwgPSBgCiAgICAgICAgICAg ICAgICAgICAgPGRpdiBzdHlsZT0iaGVpZ2h0OiAxMDAlOyBvdmVyZmxvdzogYXV0bzsgbWFyZ2lu LXJpZ2h0OiAzMHB4Ij4KICAgICAgICAgICAgICAgICAgICAgICAgPHNsb3Q+PC9zbG90PgogICAg ICAgICAgICAgICAgICAgIDwvZGl2PmA7CiAgICAgICAgfQogICAgfQoKICAgIGN1c3RvbUVsZW1l bnRzLmRlZmluZSgndGVzdC1jb250YWluZXInLCBUZXN0Q29udGFpbmVyKTsKPC9zY3JpcHQ+Cgo8 L2JvZHk+CjwvaHRtbD4K