---
title: "onPreviewKeyEvent"
description: "Adding this [modifier][Modifier] to the [modifier][Modifier] parameter of a component will allow
it to intercept hardware key events when it (or one of its children) is focused."
type: "modifier"
---

<div class='type'>Compose Modifier</div>

<a id='references'></a>
<div class='sourceset sourceset-common'>Common</div>


```kotlin
fun Modifier.onPreviewKeyEvent(onPreviewKeyEvent: (KeyEvent) -> Boolean): Modifier
```


Adding this `modifier` to the `modifier` parameter of a component will allow
it to intercept hardware key events when it (or one of its children) is focused.

#### Parameters

| | |
| --- | --- |
| onPreviewKeyEvent | This callback is invoked when the user interacts with the hardware keyboard. It gives ancestors of a focused component the chance to intercept a `KeyEvent`. Return true to stop propagation of this event. If you return false, the key event will be sent to this `onPreviewKeyEvent`'s child. If none of the children consume the event, it will be sent back up to the root `KeyInputModifierNode` using the onKeyEvent callback. |




## Code Examples
### KeyEventSample
```kotlin
@Suppress("UNUSED_ANONYMOUS_PARAMETER")
@Composable
fun KeyEventSample() {
    // When the inner Box is focused, and the user presses a key, the key goes down the hierarchy
    // and then back up to the parent. At any stage you can stop the propagation by returning
    // true to indicate that you consumed the event.
    Box(Modifier.onPreviewKeyEvent { keyEvent1 -> false }.onKeyEvent { keyEvent4 -> false }) {
        Box(
            Modifier.onPreviewKeyEvent { keyEvent2 -> false }
                .onKeyEvent { keyEvent3 -> false }
                .focusable()
        )
    }
}
```