# LinearSmoothScroller
# LinearSmoothScroller
Artifact:[androidx.recyclerview:recyclerview](https://developer.android.com/jetpack/androidx/releases/recyclerview)
[View Source](https://cs.android.com/search?q=file:androidx/recyclerview/widget/LinearSmoothScroller.java+class:androidx.recyclerview.widget.LinearSmoothScroller)
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
*** ** * ** ***
Kotlin\|[Java](https://developer.android.com/reference/androidx/recyclerview/widget/LinearSmoothScroller "View this page in Java")
```
class LinearSmoothScroller : RecyclerView.SmoothScroller
```
|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------|
| [kotlin.Any](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html) |||
| ↳ | [androidx.recyclerview.widget.RecyclerView.SmoothScroller](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller) ||
| | ↳ | [androidx.recyclerview.widget.LinearSmoothScroller](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller) |
*** ** * ** ***
[RecyclerView.SmoothScroller](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller)implementation which uses a[LinearInterpolator](https://developer.android.com/reference/android/view/animation/LinearInterpolator.html)until the target position becomes a child of the RecyclerView and then uses a[DecelerateInterpolator](https://developer.android.com/reference/android/view/animation/DecelerateInterpolator.html)to slowly approach to target position.
If the[RecyclerView.LayoutManager](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.LayoutManager)you are using does not implement the[RecyclerView.SmoothScroller.ScrollVectorProvider](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller.ScrollVectorProvider)interface, then you must override the[computeScrollVectorForPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#computeScrollVectorForPosition(int))method. All the LayoutManagers bundled with the support library implement this interface.
## Summary
| ### Constants |
|-------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [SNAP_TO_ANY](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_ANY())` = 0` Decides if the child should be snapped from start or end, depending on where it currently is in relation to its parent. |
| `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END())` = 1` Align child view's right or bottom with parent view's right or bottom |
| `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [SNAP_TO_START](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_START())` = -1` Align child view's left or top with parent view's left or top |
| ### Public constructors |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [LinearSmoothScroller](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#LinearSmoothScroller(android.content.Context))`(context: `[Context](https://developer.android.com/reference/android/content/Context.html)`!)` |
| ### Public functions |
|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [calculateDtToFit](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDtToFit(int,int,int,int,int))`(` ` viewStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` viewEnd: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` boxStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` boxEnd: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` snapPreference: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) `)` Helper method for[calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int))and[calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int)) |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int))`(view: `[View](https://developer.android.com/reference/android/view/View.html)`!, snapPreference: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Calculates the horizontal scroll amount necessary to make the given view fully visible inside the RecyclerView. |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int))`(view: `[View](https://developer.android.com/reference/android/view/View.html)`!, snapPreference: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Calculates the vertical scroll amount necessary to make the given view fully visible inside the RecyclerView. |
| ### Protected functions |
|---------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Float](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html) | [calculateSpeedPerPixel](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateSpeedPerPixel(android.util.DisplayMetrics))`(displayMetrics: `[DisplayMetrics](https://developer.android.com/reference/android/util/DisplayMetrics.html)`!)` Calculates the scroll speed. |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [calculateTimeForDeceleration](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateTimeForDeceleration(int))`(dx: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Calculates the time for deceleration so that transition from LinearInterpolator to DecelerateInterpolator looks smooth. |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [calculateTimeForScrolling](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateTimeForScrolling(int))`(dx: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Calculates the time it should take to scroll the given distance (in pixels) |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [getHorizontalSnapPreference](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#getHorizontalSnapPreference())`()` When scrolling towards a child view, this method defines whether we should align the left or the right edge of the child with the parent RecyclerView. |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [getVerticalSnapPreference](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#getVerticalSnapPreference())`()` When scrolling towards a child view, this method defines whether we should align the top or the bottom edge of the child with the parent RecyclerView. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onSeekTargetStep](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#onSeekTargetStep(int,int,androidx.recyclerview.widget.RecyclerView.State,androidx.recyclerview.widget.RecyclerView.SmoothScroller.Action))`(` ` dx: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` dy: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`,` ` state: `[RecyclerView.State](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.State)`!,` ` action: `[RecyclerView.SmoothScroller.Action](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller.Action)`!` `)` RecyclerView will call this method each time it scrolls until it can find the target position in the layout. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onStart](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#onStart())`()` Called when smooth scroll is started. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onStop](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#onStop())`()` Called when smooth scroller is stopped. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onTargetFound](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#onTargetFound(android.view.View,androidx.recyclerview.widget.RecyclerView.State,androidx.recyclerview.widget.RecyclerView.SmoothScroller.Action))`(` ` targetView: `[View](https://developer.android.com/reference/android/view/View.html)`!,` ` state: `[RecyclerView.State](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.State)`!,` ` action: `[RecyclerView.SmoothScroller.Action](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller.Action)`!` `)` Called when the target position is laid out. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [updateActionForInterimTarget](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#updateActionForInterimTarget(androidx.recyclerview.widget.RecyclerView.SmoothScroller.Action))`(` ` action: `[RecyclerView.SmoothScroller.Action](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller.Action)`!` `)` When the target scroll position is not a child of the RecyclerView, this method calculates a direction vector towards that child and triggers a smooth scroll. |
| ### Protected properties |
|-------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------|
| [DecelerateInterpolator](https://developer.android.com/reference/android/view/animation/DecelerateInterpolator.html)`!` | [mDecelerateInterpolator](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#mDecelerateInterpolator()) |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [mInterimTargetDx](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#mInterimTargetDx()) |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [mInterimTargetDy](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#mInterimTargetDy()) |
| [LinearInterpolator](https://developer.android.com/reference/android/view/animation/LinearInterpolator.html)`!` | [mLinearInterpolator](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#mLinearInterpolator()) |
| [PointF](https://developer.android.com/reference/android/graphics/PointF.html)`!` | [mTargetVector](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#mTargetVector()) |
| ### Inherited functions |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| From[androidx.recyclerview.widget.RecyclerView.SmoothScroller](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller) |-----------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [PointF](https://developer.android.com/reference/android/graphics/PointF.html)`?` | [computeScrollVectorForPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#computeScrollVectorForPosition(int))`(targetPosition: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Compute the scroll vector for a given target position. | | [View](https://developer.android.com/reference/android/view/View.html)`!` | [findViewByPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#findViewByPosition(int))`(position: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` | | [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [getChildCount](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#getChildCount())`()` | | [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [getChildPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#getChildPosition(android.view.View))`(view: `[View](https://developer.android.com/reference/android/view/View.html)`!)` | | [RecyclerView.LayoutManager](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.LayoutManager)`?` | [getLayoutManager](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#getLayoutManager())`()` | | [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [getTargetPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#getTargetPosition())`()` Returns the adapter position of the target item | | [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | ~~[instantScrollToPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#instantScrollToPosition(int))~~`(position: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` **This function is deprecated.** Use[jumpTo](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller.Action#jumpTo(int)).
| | [Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html) | [isPendingInitialRun](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#isPendingInitialRun())`()` Returns true if SmoothScroller has been started but has not received the first animation callback yet. | | [Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html) | [isRunning](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#isRunning())`()` | | [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [normalize](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#normalize(android.graphics.PointF))`(scrollVector: `[PointF](https://developer.android.com/reference/android/graphics/PointF.html)`)` Normalizes the vector. | | [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onChildAttachedToWindow](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#onChildAttachedToWindow(android.view.View))`(child: `[View](https://developer.android.com/reference/android/view/View.html)`!)` | | [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [setTargetPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#setTargetPosition(int))`(targetPosition: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` | | [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [stop](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#stop())`()` Stops running the SmoothScroller in each animation callback. | |
## Constants
### SNAP_TO_ANY
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
const val SNAP_TO_ANY = 0: Int
```
Decides if the child should be snapped from start or end, depending on where it currently is in relation to its parent.
For instance, if the view is virtually on the left of RecyclerView, using`SNAP_TO_ANY`is the same as using`SNAP_TO_START`
| See also |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [calculateDtToFit](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDtToFit(int,int,int,int,int)) | |
| [calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int)) | |
| [calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int)) | |
### SNAP_TO_END
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
const val SNAP_TO_END = 1: Int
```
Align child view's right or bottom with parent view's right or bottom
| See also |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [calculateDtToFit](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDtToFit(int,int,int,int,int)) | |
| [calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int)) | |
| [calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int)) | |
### SNAP_TO_START
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
const val SNAP_TO_START = -1: Int
```
Align child view's left or top with parent view's left or top
| See also |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [calculateDtToFit](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDtToFit(int,int,int,int,int)) | |
| [calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int)) | |
| [calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int)) | |
## Public constructors
### LinearSmoothScroller
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
LinearSmoothScroller(context: Context!)
```
## Public functions
### calculateDtToFit
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
fun calculateDtToFit(
viewStart: Int,
viewEnd: Int,
boxStart: Int,
boxEnd: Int,
snapPreference: Int
): Int
```
Helper method for[calculateDxToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDxToMakeVisible(android.view.View,int))and[calculateDyToMakeVisible](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateDyToMakeVisible(android.view.View,int))
### calculateDxToMakeVisible
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
fun calculateDxToMakeVisible(view: View!, snapPreference: Int): Int
```
Calculates the horizontal scroll amount necessary to make the given view fully visible inside the RecyclerView.
| Parameters |
|-----------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `view: `[View](https://developer.android.com/reference/android/view/View.html)`!` | The view which we want to make fully visible |
| `snapPreference: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | The edge which the view should snap to when entering the visible area. One of[SNAP_TO_START](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_START()),[SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END())or[SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END()) |
| Returns |
|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | The vertical scroll amount necessary to make the view visible with the given snap preference. |
### calculateDyToMakeVisible
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
fun calculateDyToMakeVisible(view: View!, snapPreference: Int): Int
```
Calculates the vertical scroll amount necessary to make the given view fully visible inside the RecyclerView.
| Parameters |
|-----------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `view: `[View](https://developer.android.com/reference/android/view/View.html)`!` | The view which we want to make fully visible |
| `snapPreference: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | The edge which the view should snap to when entering the visible area. One of[SNAP_TO_START](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_START()),[SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END())or[SNAP_TO_ANY](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_ANY()). |
| Returns |
|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | The vertical scroll amount necessary to make the view visible with the given snap preference. |
## Protected functions
### calculateSpeedPerPixel
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun calculateSpeedPerPixel(displayMetrics: DisplayMetrics!): Float
```
Calculates the scroll speed.
By default, LinearSmoothScroller assumes this method always returns the same value and caches the result of calling it.
| Parameters |
|-----------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------|
| `displayMetrics: `[DisplayMetrics](https://developer.android.com/reference/android/util/DisplayMetrics.html)`!` | DisplayMetrics to be used for real dimension calculations |
| Returns |
|---------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Float](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html) | The time (in ms) it should take for each pixel. For instance, if returned value is 2 ms, it means scrolling 1000 pixels with LinearInterpolation should take 2 seconds. |
### calculateTimeForDeceleration
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun calculateTimeForDeceleration(dx: Int): Int
```
Calculates the time for deceleration so that transition from LinearInterpolator to DecelerateInterpolator looks smooth.
| Parameters |
|-----------------------------------------------------------------------------------|--------------------|
| `dx: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | Distance to scroll |
| Returns |
|-----------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | Time for DecelerateInterpolator to smoothly traverse the distance when transitioning from LinearInterpolation |
### calculateTimeForScrolling
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun calculateTimeForScrolling(dx: Int): Int
```
Calculates the time it should take to scroll the given distance (in pixels)
| Parameters |
|-----------------------------------------------------------------------------------|-------------------------------------------|
| `dx: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | Distance in pixels that we want to scroll |
| Returns |
|-----------------------------------------------------------------------------|----------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | Time in milliseconds |
| See also |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [calculateSpeedPerPixel](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#calculateSpeedPerPixel(android.util.DisplayMetrics)) | |
### getHorizontalSnapPreference
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun getHorizontalSnapPreference(): Int
```
When scrolling towards a child view, this method defines whether we should align the left or the right edge of the child with the parent RecyclerView.
| Returns |
|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | SNAP_TO_START, SNAP_TO_END or SNAP_TO_ANY; depending on the current target vector |
| See also |
|-----------------------------------------------------------------------------------------------------------------------------------|---|
| [SNAP_TO_START](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_START()) | |
| [SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END()) | |
| [SNAP_TO_ANY](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_ANY()) | |
### getVerticalSnapPreference
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun getVerticalSnapPreference(): Int
```
When scrolling towards a child view, this method defines whether we should align the top or the bottom edge of the child with the parent RecyclerView.
| Returns |
|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | SNAP_TO_START, SNAP_TO_END or SNAP_TO_ANY; depending on the current target vector |
| See also |
|-----------------------------------------------------------------------------------------------------------------------------------|---|
| [SNAP_TO_START](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_START()) | |
| [SNAP_TO_END](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_END()) | |
| [SNAP_TO_ANY](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/LinearSmoothScroller#SNAP_TO_ANY()) | |
### onSeekTargetStep
Added in[1.4.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.4.0)
```
protected fun onSeekTargetStep(
dx: Int,
dy: Int,
state: RecyclerView.State!,
action: RecyclerView.SmoothScroller.Action!
): Unit
```
RecyclerView will call this method each time it scrolls until it can find the target position in the layout.
SmoothScroller should check dx, dy and if scroll should be changed, update the provided to define the next scroll.
### onStart
Added in[1.4.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.4.0)
```
protected fun onStart(): Unit
```
Called when smooth scroll is started. This might be a good time to do setup.
### onStop
Added in[1.4.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.4.0)
```
protected fun onStop(): Unit
```
Called when smooth scroller is stopped. This is a good place to cleanup your state etc.
### onTargetFound
Added in[1.4.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.4.0)
```
protected fun onTargetFound(
targetView: View!,
state: RecyclerView.State!,
action: RecyclerView.SmoothScroller.Action!
): Unit
```
Called when the target position is laid out. This is the last callback SmoothScroller will receive and it should update the provided to define the scroll details towards the target view.
### updateActionForInterimTarget
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected fun updateActionForInterimTarget(
action: RecyclerView.SmoothScroller.Action!
): Unit
```
When the target scroll position is not a child of the RecyclerView, this method calculates a direction vector towards that child and triggers a smooth scroll.
| See also |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [computeScrollVectorForPosition](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.SmoothScroller#computeScrollVectorForPosition(int)) | |
## Protected properties
### mDecelerateInterpolator
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected val mDecelerateInterpolator: DecelerateInterpolator!
```
### mInterimTargetDx
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected val mInterimTargetDx: Int
```
### mInterimTargetDy
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected val mInterimTargetDy: Int
```
### mLinearInterpolator
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected val mLinearInterpolator: LinearInterpolator!
```
### mTargetVector
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)
```
protected val mTargetVector: PointF!
```