Bug 197783

Summary: Backing sharing should not happen for stacking-order descendants of already-sharing layers
Product: WebKit Reporter: Simon Fraser (smfr) <simon.fraser>
Component: CompositingAssignee: Nobody <webkit-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 197561    
Attachments:
Description Flags
Testcase (shows incorrect opacity rendering) none

Description Simon Fraser (smfr) 2019-05-10 10:14:57 PDT
We should never do this:

S--------C-c- -- ------ ------ 0x3a6878560 (0,0) width=600 height=588 (layerID 241) {sc 28} RenderView
S----------c- -- ------ ------   + 0x3a68786b8 (0,0) width=600 height=322  <html>
-NO------CP-- -- ------ ------     n 0x3a6878810 (18,10) width=302 height=302 (layerID 246) {sc 29}  <div> class='scrollable'
S--A------p-s -- ------ ------     + 0x3a6878968 (31,31) width=200 height=200  <div> class='outer sharing'
----------p-s -- ------ ------       + 0x3a6878ac0 (30,30) width=200 height=200  <div> class='sharing'

0x3a6878968 is already sharing, so 0x3a6878ac0 should just paint into it, rather than also sharing.

This is causing assertions when trying to get painting with transforms working. We need to behave more like 0x3a6878968 was compositing.
Comment 1 Simon Fraser (smfr) 2019-05-10 10:15:16 PDT
Created attachment 369560 [details]
Testcase (shows incorrect opacity rendering)
Comment 2 Radar WebKit Bug Importer 2019-05-10 17:41:56 PDT
<rdar://problem/50684464>
Comment 3 Simon Fraser (smfr) 2019-05-10 17:51:18 PDT
This bug leads to incorrect rendering of sharing layers with opacity, and assertions. It's required before bug 197692 can be fixed.
Comment 4 Simon Fraser (smfr) 2019-05-11 10:21:22 PDT
Bug 197692 fixed this

*** This bug has been marked as a duplicate of bug 197692 ***