Common
```kotlin
public fun interface PlaceholderSize
```
PlaceholderSize defines the size of the space that was or will be occupied by the exiting or
entering `sharedElement`/`sharedBounds`.
## Functions
calculateSize
```kotlin
public fun calculateSize(contentSize: IntSize, animatedSize: IntSize): IntSize
```
Returns the size of the placeholder based on `contentSize` and `animatedSize`. Note:
`contentSize` for exiting content is the size before it starts exiting. For entering
content, `contentSize` is the lookahead size of the content (i.e. target size of the
shared transition).