Bug 207089

Summary:

Fixed elements should stay fixed with pinch-to-zoom

Product:

WebKit

Reporter:

cc.glows

Component:

Scrolling

Assignee:

Nobody <webkit-unassigned>

Status:

NEW

Severity:

Normal

CC:

alexander, brian, kyle.bavender, simon.fraser, thorton, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

Safari 13

Hardware:

Mac

OS:

macOS 10.15

Attachments:

Description	Flags
Video demonstration of the reproduction	none
Test HTML	none

cc.glows

Reported 2020-02-01 01:38:12 PST

When pinch-to-zooming, `fixed` elements don't stay fixed for a period and can be scrolled, but elements positioned relative to it with `fixed` get positioned incorrectly when using `getBoundingClientRect()`. This doesn't occur when zoomed out normally (0:00 - 0:05). When pinch to zooming as well, fixed elements can suddenly disappear after zooming in with pinch-to-zoom. Scroll down to the bottom right of the page in the repro and zoom in. Minimal reproduction: <!DOCTYPE html> <title>Basic Visual Test</title> <style> body { height: 3000px; width: 3000px; } #reference { position: fixed; top: 150px; left: 150px; width: 200px; height: 200px; background-color: red; box-shadow: inset 0 0 0 1px black; } #popper { width: 100px; height: 100px; background-color: rebeccapurple; box-shadow: inset 0 0 0 1px black; } </style> <div id="reference">Reference Box</div> <div id="popper">Popper Box</div> <script> popper.style.position = 'fixed'; function update() { const refRect = reference.getBoundingClientRect(); const popRect = popper.getBoundingClientRect(); popper.style.left = `${refRect.right}px`; popper.style.top = `${refRect.top + popRect.height / 2}px`; } window.addEventListener('scroll', update); update(); </script>

Attachments
Video demonstration of the reproduction (2.14 MB, video/quicktime) 2020-02-01 01:48 PST, cc.glows	no flags	Details
Test HTML (858 bytes, text/html) 2020-02-03 10:39 PST, Simon Fraser (smfr)	no flags	Details
View All Add attachment proposed patch, testcase, etc.

cc.glows

Comment 1 2020-02-01 01:48:10 PST

Created attachment 389456 [details] Video demonstration of the reproduction Attached a video that was missing in the original post. Apologies for the redundant wording in it — I can't edit it.

Radar WebKit Bug Importer

Comment 2 2020-02-02 13:13:49 PST

<rdar://problem/59097233>

Simon Fraser (smfr)

Comment 3 2020-02-03 10:39:03 PST

Created attachment 389537 [details] Test HTML

Alex

Comment 4 2025-11-28 06:22:20 PST

Even getBoundingClientRect() does not work reliably on iOS in 2k25, bug is assigned to Nobody, status NEW. Reported 5 years ago, likely never even worked, likely never will. 4 trillion dollar company, everybody. You should be ashamed.

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