Compose Multiplatformのそれっぽいドロップダウンの書き方

Desktopアプリ作成でドロップダウンメニューを作ろうとしたが、意外と実装するのに苦労した。
Boxを上手に使うと表示周りの表現を柔軟にできそう。

f:id:snicmakino:20220203033811p:plain
dropdown

import androidx.compose.foundation.BorderStroke
import androidx.compose.foundation.border
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.DropdownMenu
import androidx.compose.material.DropdownMenuItem
import androidx.compose.material.Icon
import androidx.compose.material.Text
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.ArrowDropDown
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp

@Composable
fun Dropdown() {
    val options = listOf("Option 1", "Option 2", "Option 3", "Option 4", "Option 5")
    val expanded = remember { mutableStateOf(false) }
    val selectedOptionText = remember { mutableStateOf(options[0]) }

    Box(
        contentAlignment = Alignment.CenterStart,
        modifier = Modifier
            .size(250.dp, 50.dp)
            .clip(RoundedCornerShape(4.dp))
            .border(BorderStroke(1.dp, Color.LightGray), RoundedCornerShape(4.dp))
            .clickable { expanded.value = !expanded.value },
    ) {
        Text(
            text = selectedOptionText.value,
            modifier = Modifier.padding(start = 10.dp)
        )
        Icon(
            Icons.Filled.ArrowDropDown, "contentDescription",
            Modifier.align(Alignment.CenterEnd)
        )
        DropdownMenu(
            expanded = expanded.value,
            onDismissRequest = { expanded.value = false }
        ) {
            options.forEach { selectionOption ->
                DropdownMenuItem(
                    onClick = {
                        selectedOptionText.value = selectionOption
                        expanded.value = false
                    }
                ) {
                    Text(text = selectionOption)
                }
            }
        }
    }
}