Bug 219005

Summary: Implement ResizeObserver's devicePixelContentBox
Product: WebKit Reporter: Kenneth Russell <kbr>
Component: DOMAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Enhancement CC: cathiechen, cdumez, daxpedda, dino, fred.wang, gman, jdarpinian, karl+webkit, kkinnunen, koivisto, ricardovalero95, rik, simon.fraser, smoley, thorton, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=230242
Bug Depends on: 157743    
Bug Blocks: 244141    

Description Kenneth Russell 2020-11-16 14:39:26 PST 
ResizeObserver has gained the ability to observe the number of device pixels that a given element covers in the "device-pixel-content-box" observation:
https://www.w3.org/TR/resize-observer/#dom-resizeobserverboxoptions-device-pixel-content-box

This feature was discussed and specified in the CSS working group. Some concerns were raised by WebKit engineers at the time that WebKit can only provide an accurate answer for this observation after, and not before, the paint cycle runs. Even with this concern, this feature is important for web applications that expect to be able to do pixel-accurate rendering.

Now that WebKit has ResizeObserver support (thanks to Igalia folks for implementing it!), would it be possible to do at least a first-cut implementation of this new observation? It should make the example in the article https://web.dev/device-pixel-content-box/ render more stably. Currently it shows bad moiré effects in Safari Technology Preview on Retina display MacBook Pros.
Comment 1 Radar WebKit Bug Importer 2020-11-16 18:54:03 PST 
<rdar://problem/71469186>
Comment 2 Simon Fraser (smfr) 2021-09-14 12:58:15 PDT 
Some discussion that might result in spec changes here: https://github.com/w3c/csswg-drafts/issues/6608
Comment 3 Karl Dubost 2023-11-20 06:08:59 PST 
*** Bug 264158 has been marked as a duplicate of this bug. ***