dragAndDropTarget

fun Modifier.dragAndDropTarget(
    shouldStartDragAndDrop: (startEvent: DragAndDropEvent) -> Boolean,
    target: DragAndDropTarget
): Modifier

import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.draganddrop.dragAndDropTarget
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.Text
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draganddrop.DragAndDropEvent
import androidx.compose.ui.draganddrop.DragAndDropTarget
import androidx.compose.ui.draganddrop.mimeTypes
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp

val validMimeTypePrefixes = remember {
    setOf(ClipDescription.MIMETYPE_TEXT_INTENT, "image/", "text/", "video/", "audio/")
}
var backgroundColor by remember { mutableStateOf(Color.Transparent) }
val dragAndDropTarget = remember {
    object : DragAndDropTarget {
        override fun onStarted(event: DragAndDropEvent) {
            backgroundColor = Color.DarkGray.copy(alpha = 0.2f)
        }

        override fun onDrop(event: DragAndDropEvent): Boolean {
            onDragAndDropEventDropped(event)
            return true
        }

        override fun onEnded(event: DragAndDropEvent) {
            backgroundColor = Color.Transparent
        }
    }
}
Box(
    modifier =
        Modifier.fillMaxSize()
            .dragAndDropTarget(
                shouldStartDragAndDrop = accept@{ startEvent ->
                        val hasValidMimeType =
                            startEvent.mimeTypes().any { eventMimeType ->
                                validMimeTypePrefixes.any(eventMimeType::startsWith)
                            }
                        hasValidMimeType
                    },
                target = dragAndDropTarget,
            )
            .background(backgroundColor)
            .border(width = 4.dp, color = Color.Magenta, shape = RoundedCornerShape(16.dp))
) {
    when (eventSummary) {
        null -> Text(modifier = Modifier.align(Alignment.Center), text = "Drop anything here")
        else ->
            Text(
                modifier =
                    Modifier.padding(horizontal = 16.dp, vertical = 24.dp)
                        .verticalScroll(rememberScrollState()),
                text = eventSummary,
            )
    }
}