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Sebastian Markbåge
cabd8a0e70
This adds five props to `<ViewTransition>` that adds a specific
`view-transition-class` when React wants to animate it based on the
heuristic that triggers.
```js
<ViewTransition
enter="slide-from-left"
exit="slide-to-right"
layout="slide"
update="none"
share="cross-fade"
>
```
- `enter`: The <ViewTransition> or its parent Component is mounted and
there's no other <ViewTransition> with the same name being deleted.
- `exit`: The <ViewTransition> or its parent Component is unmounted and
there's no other <ViewTransition> with the same name being deleted.
- `layout`: There are no updates to the content inside this
<ViewTransition> boundary itself but the boundary has resized or moved
due to other changes to siblings.
- `share`: This <ViewTransition> is being mounted and another
<ViewTransition> instance with the same name is being unmounted
elsewhere.
- `update`: The content of <ViewTransition> has changed either due to
DOM mutations or because an inner child <ViewTransition> has resized.
The existing `className` is the baseline and the others are added to it
to combine.
This is convenient to distinguish things like `enter` / `exit` but that
can already be expressed as CSS. The other cases can't be expressed as
purely CSS.
`"none"` is a special value that deactivates the view transition name
under that condition.
The most important feature of this is that you can now limit View
Transitions to only tigger when a particular DOM node is affected, not
when just any child updates, by opt-ing out a subtree. This is safer
when added to shared parent.
```js
<ViewTransition>
<div>
<ViewTransition className="none">
{children}
</ViewTransition>
</div>
</ViewTransition>
```
This can't be fully expressed using neither just CSS nor the imperative
refs API since we need some way to have already removed the
`view-transition-name` when this happens. When you think about the
implementation details it might seem a bit strange that you specify the
`class` to `none` to remove the `name` but it's really about picking
which animation should happen for that case default (`undefined`), a
specific one (class) or none (`"none"`).