ScalingLazyListItemInfo.kt
/*
* Copyright 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.wear.compose.foundation.lazy
/**
* Contains useful information about an individual item in a [ScalingLazyColumn].
*
* @see ScalingLazyListLayoutInfo
*/
public sealed interface ScalingLazyListItemInfo {
/**
* The index of the item in the list.
*/
val index: Int
/**
* The key of the item which was passed to the item() or items() function.
*/
val key: Any
/**
* The main axis offset of the item before adjustment for scaling of the items in the viewport.
*
* The offset is relative to the center-line of the viewport of the lazy list container and
* takes the [ScalingLazyListAnchorType] into account.
*
* For [ScalingLazyListAnchorType.ItemCenter] the offset is from the center of the list item to
* the center-line of the viewport.
*
* For [ScalingLazyListAnchorType.ItemStart] if is the offset
* between the start (edge) of the item and the center-line of the viewport, for normal layout
* this will be the top edge of the item, for reverseLayout it will be the bottom edge.
*/
val unadjustedOffset: Int
/**
* The main axis offset of the item after adjustment for scaling of the items in the viewport.
*
* The offset is relative to the center-line of the viewport of the lazy list container and
* takes the [ScalingLazyListAnchorType] into account.
*
* For [ScalingLazyListAnchorType.ItemCenter] the offset is from the center of the list item to
* the center-line of the viewport.
*
* For [ScalingLazyListAnchorType.ItemStart] if is the offset
* between the start (edge) of the item and the center-line of the viewport, for normal layout
* this will be the top edge of the item, for reverseLayout it will be the bottom edge.
*
* A positive value indicates that the item's anchor point is below the viewport center-line, a
* negative value indicates that the item anchor point is above the viewport center-line.
*/
val offset: Int
/**
* The scaled/adjusted main axis size of the item. Note that if you emit multiple layouts in the
* composable slot for the item then this size will be calculated as the sum of their sizes.
*/
val size: Int
/**
* How much scaling has been applied to the item, between 0 and 1
*/
val scale: Float
/**
* How much alpha has been applied to the item, between 0 and 1
*/
val alpha: Float
/**
* The original (before scaling) size of the list item
*/
val unadjustedSize: Int
}