{% setvar book_path %}/reference/androidx/_book.yaml{% endsetvar %} {% include "_shared/_reference-head-tags.html" %}

AnimationModifierKt

public final class AnimationModifierKt


Summary

Public methods

static final @NonNull Modifier
animateContentSize(
    @NonNull Modifier receiver,
    @NonNull FiniteAnimationSpec<@NonNull IntSize> animationSpec,
    Function2<@NonNull IntSize, @NonNull IntSizeUnit> finishedListener
)

This modifier animates its own size when its child modifier (or the child composable if it is already at the tail of the chain) changes size.

Public methods

animateContentSize

public static final @NonNull Modifier animateContentSize(
    @NonNull Modifier receiver,
    @NonNull FiniteAnimationSpec<@NonNull IntSize> animationSpec,
    Function2<@NonNull IntSize, @NonNull IntSizeUnit> finishedListener
)

This modifier animates its own size when its child modifier (or the child composable if it is already at the tail of the chain) changes size. This allows the parent modifier to observe a smooth size change, resulting in an overall continuous visual change.

A FiniteAnimationSpec can be optionally specified for the size change animation. By default, spring will be used.

An optional finishedListener can be supplied to get notified when the size change animation is finished. Since the content size change can be dynamic in many cases, both initial value and target value (i.e. final size) will be passed to the finishedListener. Note: if the animation is interrupted, the initial value will be the size at the point of interruption. This is intended to help determine the direction of the size change (i.e. expand or collapse in x and y dimensions).

import androidx.compose.animation.animateContentSize
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.LocalTextStyle
import androidx.compose.material.Text
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp

val shortText = "Hi"
val longText = "Very long text\nthat spans across\nmultiple lines"
var short by remember { mutableStateOf(true) }
Box(
    modifier = Modifier
        .background(
            Color.Blue,
            RoundedCornerShape(15.dp)
        )
        .clickable { short = !short }
        .padding(20.dp)
        .wrapContentSize()
        .animateContentSize()
) {
    Text(
        if (short) {
            shortText
        } else {
            longText
        },
        style = LocalTextStyle.current.copy(color = Color.White)
    )
}
Parameters
@NonNull FiniteAnimationSpec<@NonNull IntSize> animationSpec

a finite animation that will be used to animate size change, spring by default

Function2<@NonNull IntSize, @NonNull IntSizeUnit> finishedListener

an optional listener to be called when the content change animation is completed.