Bug 185001

Summary: Click events on outer page are not being dispatched correctly after touch-zooming within an iframe
Product: WebKit Reporter: Walter Kalata <wkalata>
Component: DOMAssignee: Andy Estes <aestes>
Status: RESOLVED FIXED    
Severity: Normal CC: aestes, bdakin, cdumez, commit-queue, jer.noble, megan_gardner, prlaodude, sasha.barab, simon.fraser, thorton, webkit-bug-importer, wenson_hsieh, zach
Priority: P2 Keywords: InRadar
Version: Safari 11   
Hardware: iPhone / iPad   
OS: iOS 11   
See Also: https://bugs.webkit.org/show_bug.cgi?id=182252
Attachments:
Description Flags
Iframe Zoom Click Repro
none
Simpler repro, removes unnecessary CSS; still matches the youtube video sent in an earlier comment
none
Workaround -- an empty "ontouchstart" attribute allows for the separate click event to be dispatched. The reported issue can not be reproduced using this attachment.
none
Needs a test
none
Patch
none
Fix open source build none

Walter Kalata
Reported 2018-04-25 14:46:30 PDT
Created attachment 338799 [details] Iframe Zoom Click Repro The attached file has an anchor labelled "Click Me" containing an onclick attribute of "alert('Clicked');", as well as an iframe sourced to a youtube video. Repro: 1. Focus the video in the iframe 2. Zoom In 3. Zoom Out 4. Click "Click Me" on the parent page Expectation: "alert('Clicked');" is executed and an alert box displays Observed: The click event only seems to dispatch (and the alert box display) a fraction of the time. Anecdotally, although the link should be at position 0,0 during all of the steps above, document.elementFromPoint(0, 0).click() also fails to result in a dispatched click event to the anchor element during the zoom operation as well.
Attachments
Iframe Zoom Click Repro (403 bytes, text/html)
2018-04-25 14:46 PDT, Walter Kalata 		no flags
Details
Simpler repro, removes unnecessary CSS; still matches the youtube video sent in an earlier comment (266 bytes, text/plain)
2018-06-25 13:24 PDT, Walter Kalata 		no flags
Details
Workaround -- an empty "ontouchstart" attribute allows for the separate click event to be dispatched. The reported issue can not be reproduced using this attachment. (282 bytes, text/plain)
2018-06-25 13:26 PDT, Walter Kalata 		no flags
Details
Needs a test (1.38 KB, patch)
2019-06-04 01:05 PDT, Andy Estes 		no flags
DetailsFormatted DiffDiff
Patch (12.28 KB, patch)
2019-07-03 22:49 PDT, Wenson Hsieh 		no flags
DetailsFormatted DiffDiff
Fix open source build (12.32 KB, patch)
2019-07-03 23:06 PDT, Wenson Hsieh 		no flags
DetailsFormatted DiffDiff
Show Obsolete (3) View All Add attachment proposed patch, testcase, etc.
Simon Fraser (smfr)
Comment 1 2018-05-25 16:18:54 PDT
What do you mean by "focus the video"? Should I tap the play button to start it playing?
Simon Fraser (smfr)
Comment 2 2018-05-25 16:22:34 PDT
Does the bug occur if the "Click me" is not inside position:fixed?
Radar WebKit Bug Importer
Comment 3 2018-05-25 16:25:07 PDT
<rdar://problem/40569615>
Simon Fraser (smfr)
Comment 4 2018-05-25 16:25:36 PDT
Can you put a "click me" outside the position:fixed for testing, and move it away from the edge of the page so that it's easier to test? Does the size of the hit target make any difference?
Zach
Comment 5 2018-05-25 16:50:08 PDT
I have shown the repro in a video here: https://www.youtube.com/watch?v=mqf8vJiu-yY - in the video I have taken the link out of the position: fixed container as well and it persists.
Sasha
Comment 6 2018-06-20 21:57:23 PDT
has there been any progress on this issue? It would really mean a lot. Thanks much.
Zach
Comment 7 2018-06-25 13:17:54 PDT
A temporary workaround we've found is adding a touchstart event handler to the body. After that, the click events work properly and all is good again.
Walter Kalata
Comment 8 2018-06-25 13:24:27 PDT
Created attachment 343530 [details] Simpler repro, removes unnecessary CSS; still matches the youtube video sent in an earlier comment
Walter Kalata
Comment 9 2018-06-25 13:26:09 PDT
Created attachment 343531 [details] Workaround -- an empty "ontouchstart" attribute allows for the separate click event to be dispatched. The reported issue can not be reproduced using this attachment.
Lucas Forschler
Comment 10 2019-02-06 09:19:06 PST
Mass move bugs into the DOM component.
prlaodude
Comment 11 2019-03-23 18:33:08 PDT
This is a major issue as my website consists of a feed of embedded youtube videos. UI is rendered useless on iOS. Adding ontouchstart="" to the body works in the beginning, but as the user keeps scrolling the issue presents itself again.
Simon Fraser (smfr)
Comment 12 2019-06-01 20:02:08 PDT
I can reproduce.
Simon Fraser (smfr)
Comment 13 2019-06-01 21:25:06 PDT
The issue is that if you happen to put a finger in the YouTube iframe when zooming, WebPage::updatePotentialTapSecurityOrigin() puts youtube.com's security origin in WebPage::m_potentialTapSecurityOrigin and it doesn't get cleared, causing later potential taps in the main frame to fail.
Andy Estes
Comment 14 2019-06-04 00:58:06 PDT
We assume that any time a touch event is a potential tap, our single tap gesture recognizer will identify the potential tap (even if it never commits). That's a false assumption. In this case, the first touch event in the pinch gesture is a potential tap, but the second touch event occurs before the single tap gesture recognizer identifies a potential tap.
Andy Estes
Comment 15 2019-06-04 01:04:32 PDT
That false assumption causes this bug because we set m_potentialTapSecurityOrigin when a touch event is a potential tap, but never clear it until a potential tap in the WebPage sense either commits or cancels. I think we can fix this by clearing m_potentialTapSecurityOrigin each time we see a new touch start event.
Andy Estes
Comment 16 2019-06-04 01:05:07 PDT
Created attachment 371254 [details] Needs a test
Wenson Hsieh
Comment 17 2019-07-03 22:49:36 PDT
Created attachment 373454 [details] Patch
Wenson Hsieh
Comment 18 2019-07-03 23:06:51 PDT
Created attachment 373455 [details] Fix open source build
Wenson Hsieh
Comment 19 2019-07-05 09:24:41 PDT
Comment on attachment 373455 [details] Fix open source build Thanks for the review!
WebKit Commit Bot
Comment 20 2019-07-05 09:58:12 PDT
Comment on attachment 373455 [details] Fix open source build Clearing flags on attachment: 373455 Committed r247161: <https://trac.webkit.org/changeset/247161>
WebKit Commit Bot
Comment 21 2019-07-05 09:58:13 PDT
All reviewed patches have been landed. Closing bug.
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