Re: [csswg-drafts] [css-view-transitions-2] Ignore offscreen elements from participating in transitions (#8282)

Summary of internal discussion and #10587:
WebKit has raised an implementation concern regarding displaying the live image twice.
We see a few options on how to resolve this:
1. try to figure it out in implementations
2. make this implementation-defined (maybe less recommended, a new cross-browser difference)
3. not capture any pixels at all for off-screen elements, and find some way to reflect this to the developer (a pseudo-class?). This might break some use-cases such as morphing large out-of-viewport elements into small in-viewport elements.
4. Allow user-agents to capture a lower-resolution image for offscreen elements. This is already text to that effect [here](https://drafts.csswg.org/css-view-transitions-1/#capture-rendering-characteristics) with a different purpose, elements with a large ink overflow, we can tune it a bit to clarify that it also applies for out-of-viewport elements.

I currently tend to like (4) as it allows optimizing the important things without totally breaking the user-experience or creating a new mental load on authors. It also allows different tiers of optimizations based on device/memory/whatever as the results are not web-observable and the tradeoff between performance and visual degradation can be played with.





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Received on Tuesday, 23 July 2024 15:19:18 UTC