显示的Jetpack Compose下拉菜单

问题描述

我想知道有没有Jetpack Compose的暴露下拉菜单的解决方案？对于Jetpack Compose中的这个组件，我找不到合适的解决方案。有帮助吗？

推荐答案

版本1.1.0-alpha06介绍了ExposedDropdownMenu基于ExposedDropdownMenuBox的实现，其中TextField和DropdownMenu。

类似：

    val options = listOf("Option 1", "Option 2", "Option 3", "Option 4", "Option 5")
    var expanded by remember { mutableStateOf(false) }
    var selectedOptionText by remember { mutableStateOf(options[0]) }
    
    ExposedDropdownMenuBox(
        expanded = expanded,
        onExpandedChange = {
            expanded = !expanded
        }
    ) {
        TextField(
            readOnly = true,
            value = selectedOptionText,
            onValueChange = { },
            label = { Text("Label") },
            trailingIcon = {
                ExposedDropdownMenuDefaults.TrailingIcon(
                    expanded = expanded
                )
            },
            colors = ExposedDropdownMenuDefaults.textFieldColors()
        )
        ExposedDropdownMenu(
            expanded = expanded,
            onDismissRequest = {
                expanded = false
            }
        ) {
            options.forEach { selectionOption ->
                DropdownMenuItem(
                    onClick = {
                        selectedOptionText = selectionOption
                        expanded = false
                    }
                ) {
                    Text(text = selectionOption)
                }
            }
        }
    }

版本1.0.x没有内置组件。
您可以使用OutlinedTextField+DropdownMenu。

这只是一个基本的(非常基本的)实现：

var expanded by remember { mutableStateOf(false) }
val suggestions = listOf("Item1","Item2","Item3")
var selectedText by remember { mutableStateOf("") }

var textfieldSize by remember { mutableStateOf(Size.Zero)}

val icon = if (expanded)
    Icons.Filled.ArrowDropUp //it requires androidx.compose.material:material-icons-extended
else
    Icons.Filled.ArrowDropDown


Column() {
    OutlinedTextField(
        value = selectedText,
        onValueChange = { selectedText = it },
        modifier = Modifier
            .fillMaxWidth()
            .onGloballyPositioned { coordinates ->
                //This value is used to assign to the DropDown the same width
                textfieldSize = coordinates.size.toSize()
            },
        label = {Text("Label")},
        trailingIcon = {
            Icon(icon,"contentDescription",
                 Modifier.clickable { expanded = !expanded })
        }
    )
    DropdownMenu(
        expanded = expanded,
        onDismissRequest = { expanded = false },
        modifier = Modifier
            .width(with(LocalDensity.current){textfieldSize.width.toDp()})
    ) {
        suggestions.forEach { label ->
            DropdownMenuItem(onClick = {
                selectedText = label
            }) {
                Text(text = label)
            }
        }
    }
}

这篇关于显示的Jetpack Compose下拉菜单的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！