# alpha

Common/All

## Functions summary

|---|---|---|
| `https://developer.android.com/reference/kotlin/androidx/compose/ui/Modifier` | `https://developer.android.com/reference/kotlin/androidx/compose/ui/Modifier.https://developer.android.com/reference/kotlin/androidx/compose/ui/draw/alpha.modifier#(androidx.compose.ui.Modifier).alpha(kotlin.Float)(alpha: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html)` Draw content with modified alpha that may be less than 1. | Cmn |

## Functions

### Modifier.alpha

Cmn Artifact: [androidx.compose.ui:ui](https://developer.android.com/jetpack/androidx/releases/compose-ui) [View Source](https://cs.android.com/search?q=file:androidx/compose/ui/draw/Alpha.kt+function:alpha) Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/compose-ui#1.0.0)

```
fun Modifier.alpha(alpha: Float): Modifier
```

Draw content with modified alpha that may be less than 1.

Usage of this API renders this composable into a separate graphics layer. Note when an alpha less than 1.0f is provided, contents are implicitly clipped to their bounds. This is because an intermediate compositing layer is created to render contents into first before being drawn into the destination with the desired alpha. This layer is sized to the bounds of the composable this modifier is configured on, and contents outside of these bounds are omitted.

Performance Note: For animating alpha, it is highly recommended to use `https://developer.android.com/reference/kotlin/androidx/compose/ui/graphics/graphicsLayer.modifier#(androidx.compose.ui.Modifier).graphicsLayer(kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,androidx.compose.ui.graphics.TransformOrigin,androidx.compose.ui.graphics.Shape,kotlin.Boolean,androidx.compose.ui.graphics.RenderEffect,androidx.compose.ui.graphics.Color,androidx.compose.ui.graphics.Color,androidx.compose.ui.graphics.CompositingStrategy,androidx.compose.ui.graphics.BlendMode,androidx.compose.ui.graphics.ColorFilter,androidx.compose.ui.graphics.LayerOutsets)` instead (e.g., `Modifier.graphicsLayer { alpha = ... }`). Changing the `alpha` parameter on `Modifier.alpha` causes the composable to be recomposed, which is less efficient than updating the `alpha` property within `graphicsLayer`, as `graphicsLayer` can optimize this change without requiring recomposition.

```kotlin
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.size
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.alpha
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp

Box(Modifier.size(100.dp).alpha(alpha = 0.5f).background(Color.Red))
```

| Parameters |
|---|---|
| `alpha: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html` | the fraction of children's alpha value and must be between `0` and `1`, inclusive. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/compose/ui/graphics/graphicsLayer.modifier#(androidx.compose.ui.Modifier).graphicsLayer(kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,kotlin.Float,androidx.compose.ui.graphics.TransformOrigin,androidx.compose.ui.graphics.Shape,kotlin.Boolean,androidx.compose.ui.graphics.RenderEffect,androidx.compose.ui.graphics.Color,androidx.compose.ui.graphics.Color,androidx.compose.ui.graphics.CompositingStrategy,androidx.compose.ui.graphics.BlendMode,androidx.compose.ui.graphics.ColorFilter,androidx.compose.ui.graphics.LayerOutsets)` | Example usage: |