203237 2019-10-22 00:49:51 -0700 Pinch zoom fires mouse click event with wrong evt.buttons state 2026-01-12 09:05:52 -0800 1 1 1 Unclassified WebKit UI Events Safari 13 iPhone / iPad iOS 13 NEW InRadar P2 Normal --- 1 fabian.schwarzkopf webkit-unassigned dino graouts mail seb.p.mueller thorton webkit-bug-importer wenson_hsieh oldest_to_newest 1582275 0 381520 fabian.schwarzkopf 2019-10-22 00:49:51 -0700 Created attachment 381520 Pinch zoom fires mouse click event if both fingers are lifted simultaneously Safari 13.0.1 (605.1.15) on iOS Catalina fires an artificial mouse click event after a pinch zoom gesture if both fingers are lifted simultaneously. This is important, because if they are lifted sequentially, no mouse event is fired afterwards. So this results in the following event order when logged (from newest to oldest): MOUSEUP (evt.buttons = 0, evt.button = 0) MOUSEDOWN (evt.buttons = 0, evt.button = 0) // <<--- no buttons pressed, but mouse down? MOUSEENTER (evt.buttons = 0, evt.button = 0) POINTERUP // pinch gesture finished POINTERUP POINTERDOWN POINTERDOWN // pinch gesture start This can be reproduced with the attached HTML page which has a DIV element that listens for these events and logs them onto the page. Pinching in the rectangle yields the above log. First of all, why does it even fire mouse events when the fingers are lifted simultaneously? The second and even more unexpected part about this: The buttons state doesn't make sense, i.e., a mouse down event without any buttons pressed? Besides the attached reproduction, we have a running application (https://live.yworks.com/demos/style/templatestyles/index.html) that handles both, touch and mouse input, and may get stuck after a pinch gesture due to these unexpected mouse events. 1582290 1 fabian.schwarzkopf 2019-10-22 01:28:58 -0700 Adding a mouse click listener to the attachment will also show that there is actually a mouse click event after the MOUSEDOWN and MOUSEUP. Also logging the coordinates shows that it will click somewhere between the POINTERDOWN locations. For reference, I've added another reproduction HTML with those additional coordinate logs and click listener. 1582292 2 381527 fabian.schwarzkopf 2019-10-22 01:29:51 -0700 Created attachment 381527 Additionally log coordinates and mouse click events 1582307 3 seb.p.mueller 2019-10-22 01:55:03 -0700 If you really need to send artificial mouse events after a pinch gesture (which I would vote against), it should follow some common standard. Not all user agents do this, and if they do (and developers can't disable these events or distinguish real events from synthetic events), they would need to be at least consistent, i.e. if a button is reported to be pressed down, the "buttons" field should reflect that state. And it should happen either always or never. Right now it only happens if you manage to lift your two fingers at pretty much *exactly* the same millisecond, so it's hard to reproduce consistently for some people. The fact that this only happens sporadically from a user's point of view, clearly indicates to me that this is a bug in the browser, and I think I haven't seen this problem in older versions of Safari (11?), so this is a regression that breaks JS code in some websites and apps (like mine) where after a pinch, sometimes a (mouse-) action gets triggered, erroneously. Until this gets fixed, is there a way to unambiguously classify these mouse events as synthetic events so that developers can filter these bogus events? 1583091 4 webkit-bug-importer 2019-10-23 15:31:25 -0700 <rdar://problem/56557520> 1583189 5 thorton 2019-10-23 19:11:07 -0700 There’s no way we should be firing a synthetic click in this case, for sure. And, I can reproduce. 1583252 6 seb.p.mueller 2019-10-24 00:07:44 -0700 Thanks, Tim! Do you see a way for developers to identify these bogus events, now? I guess the timing of the events is telling: if the mouse events happens within fractions of a second after a pointer-up, they are very unlikely to be "real" events. Also of course the broken evt.buttons state looks telling. But maybe there is a better way? How would you detect these bogus events in order to ignore them? We need to implement a workaround for this into our library because right now in our customers' apps this UA behavior is triggering actions that should not trigger. 1830854 7 mail 2022-01-14 02:35:55 -0800 Although this bug is still open, I'm no longer able to reproduce it in iPadOS 15.2.1. Can someone link the related/duplicate issue that solved this problem, please? 381520 2019-10-22 00:49:51 -0700 2019-10-22 01:29:51 -0700 Pinch zoom fires mouse click event if both fingers are lifted simultaneously safari-synthetic-mouse-events.html text/html 2751 fabian.schwarzkopf PCFET0NUWVBFIGh0bWw+DQo8aHRtbCBsYW5nPSJlbiI+DQo8aGVhZD4NCiAgICA8bWV0YSBjaGFy c2V0PSJVVEYtOCI+DQogICAgPHRpdGxlPlNhZmFyaSBTeW50aGV0aWMgTW91c2UgRXZlbnRzIEds aXRjaDwvdGl0bGU+DQogIDxzdHlsZT4NCiAgICAjdG91Y2gtcmVnaW9uIHsNCiAgICAgIHdpZHRo OiAzMDBweDsNCiAgICAgIGhlaWdodDogNTAwcHg7DQogICAgICBib3JkZXI6IDFweCBzb2xpZDsN CiAgICAgIHRvdWNoLWFjdGlvbjogbm9uZTsNCiAgICB9DQogICAgI2xvZy1yZWdpb24gew0KICAg ICAgcG9zaXRpb246IGFic29sdXRlOw0KICAgICAgdG9wOiAwOw0KICAgICAgbGVmdDogMzUwcHg7 DQogICAgICB3aWR0aDogY2FsYygxMDAlIC0gNDAwcHgpOw0KICAgICAgaGVpZ2h0OiAxMDAlOw0K ICAgICAgb3ZlcmZsb3c6IGF1dG87DQogICAgfQ0KICAgIC5pbmZvIHsNCiAgICAgIGZvbnQtc2l6 ZTogMTJweDsNCiAgICAgIGJhY2tncm91bmQtY29sb3I6ICNlZWU7DQogICAgfQ0KICA8L3N0eWxl 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