ScrollableState

@JvmDefaultWithCompatibility
interface ScrollableState

An object representing something that can be scrolled. This interface is implemented by states of scrollable containers such as androidx.compose.foundation.lazy.LazyListState or androidx.compose.foundation.ScrollState in order to provide low-level scrolling control via scroll, as well as allowing for higher-level scrolling functions like animateScrollBy to be implemented as extension functions on ScrollableState.

Subclasses may also have their own methods that are specific to their interaction paradigm, such as androidx.compose.foundation.lazy.LazyListState.scrollToItem.

Properties

val isScrollInProgress: Boolean

Whether this ScrollableState is currently scrolling by gesture, fling or programmatically or not.

val canScrollForward: Boolean

Whether this ScrollableState can scroll forward (consume a positive delta). This is typically false if the scroll position is equal to its maximum value, and true otherwise.

Note that true here does not imply that delta will be consumed - the ScrollableState may decide not to handle the incoming delta (such as if it is already being scrolled separately). Additionally, for backwards compatibility with previous versions of ScrollableState this value defaults to true.

val canScrollBackward: Boolean

Whether this ScrollableState can scroll backward (consume a negative delta). This is typically false if the scroll position is equal to its minimum value, and true otherwise.

Note that true here does not imply that delta will be consumed - the ScrollableState may decide not to handle the incoming delta (such as if it is already being scrolled separately). Additionally, for backwards compatibility with previous versions of ScrollableState this value defaults to true.

val lastScrolledForward: Boolean

The value of this property is true under the following scenarios, otherwise it's false.

• This ScrollableState is currently scrolling forward.
• This ScrollableState was scrolling forward in its last scroll action.

val lastScrolledBackward: Boolean

The value of this property is true under the following scenarios, otherwise it's false.

• This ScrollableState is currently scrolling backward.
• This ScrollableState was scrolling backward in its last scroll action.

Functions

suspend fun scroll(
        scrollPriority: MutatePriority = MutatePriority.Default,
        block: suspend ScrollScope.() -> Unit,
    )

Call this function to take control of scrolling and gain the ability to send scroll events via ScrollScope.scrollBy. All actions that change the logical scroll position must be performed within a scroll block (even if they don't call any other methods on this object) in order to guarantee that mutual exclusion is enforced.

If scroll is called from elsewhere with the scrollPriority higher or equal to ongoing scroll, ongoing scroll will be canceled.

fun dispatchRawDelta(delta: Float): Float

Dispatch scroll delta in pixels avoiding all scroll related mechanisms.

NOTE: unlike scroll, dispatching any delta with this method won't trigger nested scroll, won't stop ongoing scroll/drag animation and will bypass scrolling of any priority. This method will also ignore reverseDirection and other parameters set in scrollable.

This method is used internally for nested scrolling dispatch and other low level operations, allowing implementers of ScrollableState influence the consumption as suits them. Manually dispatching delta via this method will likely result in a bad user experience, you must prefer scroll method over this one.

Parameters

Returns