Android
> **Deprecated** Was moved to androidx.wear.compose.foundation.lazy package. Please use it instead
```kotlin
public object ScalingLazyColumnDefaults
```
Contains the default values used by [ScalingLazyColumn](/jetpack-compose/androidx.wear.compose/compose-material/components/ScalingLazyColumn)
## Functions
scalingParams
```kotlin
public fun scalingParams(
edgeScale: Float = 0.7f,
edgeAlpha: Float = 0.5f,
minElementHeight: Float = 0.2f,
maxElementHeight: Float = 0.6f,
minTransitionArea: Float = 0.35f,
maxTransitionArea: Float = 0.55f,
scaleInterpolator: Easing = CubicBezierEasing(0.3f, 0f, 0.7f, 1f),
viewportVerticalOffsetResolver: (Constraints) -> Int = { (it.maxHeight / 20f).toInt() },
): ScalingParams
```
Creates a [ScalingParams](/jetpack-compose/androidx.wear.compose/compose-material/interfaces/ScalingParams) that represents the scaling and alpha properties for a
[ScalingLazyColumn](/jetpack-compose/androidx.wear.compose/compose-material/components/ScalingLazyColumn).
Items in the ScalingLazyColumn have scaling and alpha effects applied to them depending on
their position in the viewport. The closer to the edge (top or bottom) of the viewport that
they are the greater the down scaling and transparency that is applied. Note that scaling and
transparency effects are applied from the center of the viewport (full size and normal
transparency) towards the edge (items can be smaller and more transparent).
Deciding how much scaling and alpha to apply is based on the position and size of the item
and on a series of properties that are used to determine the transition area for each item.
The transition area is defined by the edge of the screen and a transition line which is
calculated for each item in the list. The items transition line is based upon its size with
the potential for larger list items to start their transition earlier (closer to the center)
than smaller items.
`minTransitionArea` and `maxTransitionArea` are both in the range [0f..1f] and are the
fraction of the distance between the edge of the viewport and the center of the viewport.
E.g. a value of 0.2f for minTransitionArea and 0.75f for maxTransitionArea determines that
all transition lines will fall between 1/5th (20%) and 3/4s (75%) of the distance between the
viewport edge and center.
The size of the each item is used to determine where within the transition area range
minTransitionArea..maxTransitionArea the actual transition line will be. `minElementHeight`
and `maxElementHeight` are used along with the item height (as a fraction of the viewport
height in the range [0f..1f]) to find the transition line. So if the items size is 0.25f
(25%) of way between minElementSize..maxElementSize then the transition line will be 0.25f
(25%) of the way between minTransitionArea..maxTransitionArea.
A list item smaller than minElementHeight is rounded up to minElementHeight and larger than
maxElementHeight is rounded down to maxElementHeight. Whereabouts the items height sits
between minElementHeight..maxElementHeight is then used to determine where the transition
line sits between minTransitionArea..maxTransition area.
If an item is smaller than or equal to minElementSize its transition line with be at
minTransitionArea and if it is larger than or equal to maxElementSize its transition line
will be at maxTransitionArea.
For example, if we take the default values for minTransitionArea = 0.2f and maxTransitionArea
= 0.6f and minElementSize = 0.2f and maxElementSize= 0.8f then an item with a height of 0.4f
(40%) of the viewport height is one third of way between minElementSize and maxElementSize,
(0.4f - 0.2f) / (0.8f - 0.2f) = 0.33f. So its transition line would be one third of way
between 0.2f and 0.6f, transition line = 0.2f + (0.6f - 0.2f) * 0.33f = 0.33f.
Once the position of the transition line is established we now have a transition area for the
item, e.g. in the example above the item will start/finish its transitions when it is 0.33f
(33%) of the distance from the edge of the viewport and will start/finish its transitions at
the viewport edge.
The scaleInterpolator is used to determine how much of the scaling and alpha to apply as the
item transits through the transition area.
The edge of the item furthest from the edge of the screen is used as a scaling trigger point
for each item.
#### Parameters
| | |
| --- | --- |
| edgeScale | What fraction of the full size of the item to scale it by when most scaled, e.g. at the edge of the viewport. A value between [0f,1f], so a value of 0.2f means to scale an item to 20% of its normal size. |
| edgeAlpha | What fraction of the full transparency of the item to draw it with when closest to the edge of the screen. A value between [0f,1f], so a value of 0.2f means to set the alpha of an item to 20% of its normal value. |
| minElementHeight | The minimum element height as a ratio of the viewport size to use for determining the transition point within (`minTransitionArea`, `maxTransitionArea`) that a given content item will start to be transitioned. Items smaller than `minElementHeight` will be treated as if `minElementHeight`. Must be less than or equal to `maxElementHeight`. |
| maxElementHeight | The maximum element height as a ratio of the viewport size to use for determining the transition point within (`minTransitionArea`, `maxTransitionArea`) that a given content item will start to be transitioned. Items larger than `maxElementHeight` will be treated as if `maxElementHeight`. Must be greater than or equal to `minElementHeight`. |
| minTransitionArea | The lower bound of the transition line area, closest to the edge of the viewport. Defined as a fraction (value between 0f..1f) of the distance between the viewport edge and viewport center line. Must be less than or equal to `maxTransitionArea`. |
| maxTransitionArea | The upper bound of the transition line area, closest to the center of the viewport. The fraction (value between 0f..1f) of the distance between the viewport edge and viewport center line. Must be greater than or equal to `minTransitionArea`. |
| scaleInterpolator | An interpolator to use to determine how to apply scaling as a item transitions across the scaling transition area. |
| viewportVerticalOffsetResolver | The additional padding to consider above and below the viewport of a [ScalingLazyColumn](/jetpack-compose/androidx.wear.compose/compose-material/components/ScalingLazyColumn) when considering which items to draw in the viewport. If set to 0 then no additional padding will be provided and only the items which would appear in the viewport before any scaling is applied will be considered for drawing, this may leave blank space at the top and bottom of the viewport where the next available item could have been drawn once other items have been scaled down in size. The larger this value is set to will allow for more content items to be considered for drawing in the viewport, however there is a performance cost associated with materializing items that are subsequently not drawn. The higher/more extreme the scaling parameters that are applied to the [ScalingLazyColumn](/jetpack-compose/androidx.wear.compose/compose-material/components/ScalingLazyColumn) the more padding may be needed to ensure there are always enough content items available to be rendered. By default will be 5% of the maxHeight of the viewport above and below the content. |
snapFlingBehavior
```kotlin
@Composable
public fun snapFlingBehavior(
state: ScalingLazyListState,
snapOffset: Dp = 0.dp,
decay: DecayAnimationSpec = exponentialDecay(),
): FlingBehavior
```
Create and remember a [FlingBehavior](/jetpack-compose/androidx.compose.foundation/foundation/interfaces/FlingBehavior) that will represent natural fling curve with snap to
central item as the fling decays.
#### Parameters
| | |
| --- | --- |
| state | the state of the [ScalingLazyColumn](/jetpack-compose/androidx.wear.compose/compose-material/components/ScalingLazyColumn) |
| snapOffset | an optional offset to be applied when snapping the item. After the snap the snapped items offset will be `snapOffset`. |
| decay | the decay to use |