Trigger

Play a change effect from code, such as a click or an event, with no value to watch.

Modifier.changeEffect(trigger, effect) plays the effect each time you call trigger.fire(). It is the way to start an effect from a click, a view model event or a button elsewhere on the screen. See the triggers guide for interactions, edges and playOnStart.

Usage

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.size
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import com.jantursky.kapow.ChangeEffect
import com.jantursky.kapow.ParticleContent
import com.jantursky.kapow.ParticleShape
import com.jantursky.kapow.changeEffect
import com.jantursky.kapow.rememberKapowTrigger

@Composable
fun LikeButton() {
    val trigger = rememberKapowTrigger()
    Box(
        Modifier
            .size(64.dp)
            .changeEffect(trigger, ChangeEffect.spray(ParticleContent.shape(ParticleShape.Heart)))
            .clickable { trigger.fire() },
    )
}

Parameters

Reduced motion

The effect follows its own reduced-motion behavior, exactly as when a value changes.

Notes

• fire() can be called from any thread and never recomposes.
• Fires within one frame play once, and a fire from before the element was composed plays nothing.

Live example