PickerState

Artifact: androidx.wear.compose:compose-material

View Source

Added in 1.0.0

class PickerState : ScrollableState

---

A state object that can be hoisted to observe item selection.

In most cases, this will be created via rememberPickerState.

Summary

Public companion properties
Saver<PickerState, Any>	Saver The default Saver implementation for PickerState.

Public constructors
PickerState(     initialNumberOfOptions: Int,     initiallySelectedOption: Int,     repeatItems: Boolean )

Public functions
suspend Unit	animateScrollToOption(index: Int) Animate (smooth scroll) to the given item at index
open Float	dispatchRawDelta(delta: Float)
open suspend Unit	scroll(scrollPriority: MutatePriority, block: suspend ScrollScope.() -> Unit)
suspend Unit	scrollToOption(index: Int) Instantly scroll to an item.

Public properties
open Boolean	canScrollBackward
open Boolean	canScrollForward
open Boolean	isScrollInProgress
Int	numberOfOptions
Boolean	repeatItems if true (the default), the contents of the component will be repeated
Int	selectedOption Index of the option selected (i.e., at the center)

Inherited properties
From androidx.compose.foundation.gestures.ScrollableState open Boolean lastScrolledBackward open Boolean lastScrolledForward

Public companion properties

Saver

Added in 1.0.0

val Saver: Saver<PickerState, Any>

The default Saver implementation for PickerState.

Public constructors

PickerState

Added in 1.0.0

PickerState(
    initialNumberOfOptions: Int,
    initiallySelectedOption: Int = 0,
    repeatItems: Boolean = true
)

Parameters
initialNumberOfOptions: Int	the number of options
initiallySelectedOption: Int = 0	the option to show in the center at the start
repeatItems: Boolean = true	if true (the default), the contents of the component will be repeated

Public functions

animateScrollToOption

Added in 1.2.0

suspend fun animateScrollToOption(index: Int): Unit

Animate (smooth scroll) to the given item at index

A smooth scroll always happens to the closest item if PickerState has repeatItems=true. For example, picker values are : 0 1 2 3 0 1 2 3 0 1 2 3 Target value is 0. 0 1 2 3 >0< 1 2 3>0< 1 2 3 Picker can be scrolled forwards or backwards. To get to the target 0 it requires 1 step to scroll forwards and 3 steps to scroll backwards. Picker will be scrolled forwards as this is the closest destination.

If the distance between possible targets is the same, picker will be scrolled backwards.

import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.runtime.derivedStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.wear.compose.material.Chip
import androidx.wear.compose.material.Picker
import androidx.wear.compose.material.Text
import androidx.wear.compose.material.rememberPickerState

val coroutineScope = rememberCoroutineScope()
val state = rememberPickerState(initialNumberOfOptions = 10)
val contentDescription by remember { derivedStateOf { "${state.selectedOption + 1}" } }

Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
    Picker(
        state = state,
        separation = 4.dp,
        contentDescription = contentDescription,
    ) {
        Chip(
            onClick = { coroutineScope.launch { state.animateScrollToOption(it) } },
            label = { Text("$it") }
        )
    }
}

Parameters
index: Int	The index of the option to scroll to.

dispatchRawDelta

Added in 1.0.0

open fun dispatchRawDelta(delta: Float): Float

scroll

Added in 1.0.0

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

scrollToOption

Added in 1.0.0

suspend fun scrollToOption(index: Int): Unit

Instantly scroll to an item.

import androidx.compose.runtime.derivedStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.unit.dp
import androidx.wear.compose.material.Chip
import androidx.wear.compose.material.Picker
import androidx.wear.compose.material.Text
import androidx.wear.compose.material.rememberPickerState

val coroutineScope = rememberCoroutineScope()
val state = rememberPickerState(initialNumberOfOptions = 10)
val contentDescription by remember { derivedStateOf { "${state.selectedOption + 1}" } }
Picker(
    state = state,
    separation = 4.dp,
    contentDescription = contentDescription,
) {
    Chip(
        onClick = { coroutineScope.launch { state.scrollToOption(it) } },
        label = { Text("$it") }
    )
}

Parameters
index: Int	The index of the option to scroll to.

Public properties

canScrollBackward

open val canScrollBackward: Boolean

canScrollForward

open val canScrollForward: Boolean

isScrollInProgress

Added in 1.0.0

open val isScrollInProgress: Boolean

numberOfOptions

Added in 1.0.0

var numberOfOptions: Int

repeatItems

Added in 1.0.0

val repeatItems: Boolean

if true (the default), the contents of the component will be repeated

selectedOption

Added in 1.0.0

val selectedOption: Int

Index of the option selected (i.e., at the center)