onFocusChanged

Functions summary

Modifier
Modifier.onFocusChanged(onFocusChanged: (FocusState) -> Unit)

Add this modifier to a component to observe focus state events.
Cmn

Functions

Modifier.onFocusChanged

Cmn 
fun Modifier.onFocusChanged(onFocusChanged: (FocusState) -> Unit): Modifier

Add this modifier to a component to observe focus state events. onFocusChanged is invoked when the focus state changes. The onFocusChanged modifier listens to the state of the first focusTarget following this modifier.

import androidx.compose.foundation.border
import androidx.compose.foundation.focusable
import androidx.compose.foundation.layout.Box
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.focus.onFocusChanged
import androidx.compose.ui.graphics.Color.Companion.Black
import androidx.compose.ui.graphics.Color.Companion.Green
import androidx.compose.ui.unit.dp

var color by remember { mutableStateOf(Black) }
Box(
    Modifier.border(2.dp, color)
        // The onFocusChanged should be added BEFORE the focusable that is being observed.
        .onFocusChanged { color = if (it.isFocused) Green else Black }
        .focusable()
)

Note: If you want to be notified every time the internal focus state is written to (even if it hasn't changed), use onFocusEvent instead.