Bug 160886

Summary: Incorrect clipping of fixed elements inside element with opacity, position, mix-blend-mode or filter
Product: WebKit Reporter: valdrinkoshi
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: RESOLVED CONFIGURATION CHANGED    
Severity: Normal CC: bfulgham, dbaron, simon.fraser, sofia.pohjalainen, zalan
Priority: P2    
Version: Safari 9   
Hardware: Mac   
OS: OS X 10.10   
See Also: https://bugs.webkit.org/show_bug.cgi?id=160953
Attachments:
Description Flags
actual rendering
none
Picture of the bug on chrome(left, how it should look like) and on safari (right, with bug) none

valdrinkoshi
Reported 2016-08-15 18:04:39 PDT
Created attachment 286127 [details] actual rendering opacity, position, mix-blend-mode, filter should only create a new stacking context for its fixed descendants, and not create a containing block. Instead, in Safari this gets created, causing cropping of the fixed descendants http://jsbin.com/coxoye/2/edit?html,output
Attachments
actual rendering (14.71 KB, image/png)
2016-08-15 18:04 PDT, valdrinkoshi 		no flags
Details
Picture of the bug on chrome(left, how it should look like) and on safari (right, with bug) (641.41 KB, image/png)
2017-05-30 08:43 PDT, sofia.pohjalainen 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Simon Fraser (smfr)
Comment 1 2016-08-17 22:02:44 PDT
This is a compositing bug.
sofia.pohjalainen
Comment 2 2017-05-30 08:43:11 PDT
Created attachment 311507 [details] Picture of the bug on chrome(left, how it should look like) and on safari (right, with bug)
sofia.pohjalainen
Comment 3 2017-05-30 08:45:50 PDT
I was having this bug too. Tested on iOS 10.3 (safari, iPad). Link to demo: https://codepen.io/sofiapoh/pen/xdozJL
L. David Baron
Comment 4 2018-05-31 21:26:03 PDT
Per the spec, *filter* should create a containing block for fixed-pos descendants; see my comment at https://bugs.chromium.org/p/chromium/issues/detail?id=797493#c6 . That said, based on my test at https://dbaron.org/css/test/2018/stacking-context-z-order WebKit isn't creating a containing block for fixed descendants for any of these properties (perhaps comment 1 was indicating that comment 0's statement is too general?).
Brent Fulgham
Comment 5 2022-07-14 16:35:21 PDT
We don't see an issue with this test case. If you believe there is still an issue, could you please REOPEN this bug with a small test case illustrating the issue?
Note You need to log in before you can comment on or make changes to this bug.