Re: [csswg-drafts] [css-transitions-2] Start transitions on discrete animation types (#4441)

> What is foreseen as benefits from transitioning a discrete property in that way?

There two main benefits to transitioning discrete properties:
- Developers can use the transitionstart event to implement custom behavior. E.g. developers could prototype cross-fading of images or another effect when the background changes.
- This is very useful for holding particular discrete values for the purposes of an animation - e.g. primarily see the exit transition example at https://github.com/w3c/csswg-drafts/issues/6429#issuecomment-1318933547

I get that you're calling out the 50% flip and I agree in general most people will want the transition of these at the end if declared as a transition-property because switching immediately doesn't require any transition, however perhaps there are cases where they want the composite order of the transition animation?

> Or would we envision a different mode where the value change is performed at the _end_ of the transition?

So, developers could use `transition-timing-function` setting `step-start` or `step-end` to choose whether to hold the beginning or ending keyframe. We do define for particular properties where certain values may not be useful interpolations - e.g. display: none is useful to avoid in the same way that visibility interpolation avoids hidden: https://drafts.csswg.org/web-animations-1/#animating-visibility. I could see defaulting the timing function to step-end for discrete properties but it would be weird if you couldn't choose a different timing function.

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Received on Wednesday, 14 December 2022 17:30:06 UTC