animateFloatAsState

Common/All

Functions summary

State<Float>

@Composable animateFloatAsState(     targetValue: Float,     animationSpec: AnimationSpec<Float>,     visibilityThreshold: Float,     label: String,     finishedListener: ((Float) -> Unit)? ) Fire-and-forget animation function for Float.

Cmn

Functions

animateFloatAsState

Cmn

Artifact: androidx.compose.animation:animation-core

View Source

Added in 1.3.0

@Composable
fun animateFloatAsState(
    targetValue: Float,
    animationSpec: AnimationSpec<Float> = defaultAnimation,
    visibilityThreshold: Float = DefaultFloatVisibilityThreshold,
    label: String = "FloatAnimation",
    finishedListener: ((Float) -> Unit)? = null
): State<Float>

Fire-and-forget animation function for Float. This Composable function is overloaded for different parameter types such as Dp, Color, Offset, etc. When the provided targetValue is changed, the animation will run automatically. If there is already an animation in-flight when targetValue changes, the on-going animation will adjust course to animate towards the new target value.

animateFloatAsState returns a State object. The value of the state object will continuously be updated by the animation until the animation finishes.

Note, animateFloatAsState cannot be canceled/stopped without removing this composable function from the tree. See Animatable for cancelable animations.

visibilityThreshold can be used to define when the animation value is considered close enough to the targetValue to finish. By default, the visibilityThreshold in the animationSpec will be respected. If a non-default visibilityThreshold is provided, it will override the visibility threshold in the animationSpec if it's a SpringSpec.

import androidx.compose.animation.core.animateFloatAsState
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.graphicsLayer

@Composable
fun alphaAnimation(visible: Boolean) {
    // Animates to 1f or 0f based on [visible].
    // This [animateState] returns a State<Float> object. The value of the State object is
    // being updated by animation. (This method is overloaded for different parameter types.)
    // Here we use the returned [State] object as a property delegate.
    val alpha: Float by animateFloatAsState(if (visible) 1f else 0f)

    // Updates the alpha of a graphics layer with the float animation value. It is more
    // performant to modify alpha in a graphics layer than using `Modifier.alpha`. The former
    // limits the invalidation scope of alpha change to graphicsLayer's draw stage (i.e. no
    // recomposition would be needed). The latter triggers recomposition on each animation
    // frame.
    Box(modifier = Modifier.graphicsLayer { this.alpha = alpha }.background(Color.Red))
}

Parameters
targetValue: Float	Target value of the animation
animationSpec: AnimationSpec<Float> = defaultAnimation	The animation that will be used to change the value through time. spring will be used by default.
visibilityThreshold: Float = DefaultFloatVisibilityThreshold	An optional threshold for deciding when the animation value is considered close enough to the targetValue.
label: String = "FloatAnimation"	An optional label to differentiate from other animations in Android Studio.
finishedListener: ((Float) -> Unit)? = null	An optional end listener to get notified when the animation is finished.

Returns
State<Float>	A State object, the value of which is updated by animation.