Android 撰写文本字段 : How to set exact 3 lines

Question

我要创建TextField精确的 3 行:

即使在此 TextField 中没有任何文本，我也希望看到 3 行，即我需要 EditText.lines 的直接等价物在经典的 xml 布局中。
我不工作的代码是:

OutlinedTextField(
            value = currentText,
            onValueChange = { currentText = it },
            label = { Text ("Label") },
            maxLines = 3,
            modifier = Modifier.fillMaxWidth().wrapContentHeight().padding(16.dp),
            singleLine = false
        )

你可以帮帮我吗？

Answer 1

有一个feature request对于此功能，我建议您为它加星，并可能对其发表评论，因为它已经有一段时间没有更新了。
在此之前，您可以使用此 hack。我用额外的行渲染一个不可见的文本字段，使其占据正确的大小，然后将该大小应用于真实的文本字段。我也通过modifier和 textStyle作为 remember 的键对于 heightUpdateNeeded因此，如果您更改它们，将重新计算高度。如果您传递的任何其他参数可能会改变 View 的大小，您也应该将它们传递给记住。

@Composable
fun MinLinesOutlinedTextField(
    value: String,
    onValueChange: (String) -> Unit,
    modifier: Modifier = Modifier,
    enabled: Boolean = true,
    readOnly: Boolean = false,
    textStyle: TextStyle = LocalTextStyle.current,
    label: @Composable (() -> Unit)? = null,
    placeholder: @Composable (() -> Unit)? = null,
    leadingIcon: @Composable (() -> Unit)? = null,
    trailingIcon: @Composable (() -> Unit)? = null,
    isError: Boolean = false,
    visualTransformation: VisualTransformation = VisualTransformation.None,
    keyboardOptions: KeyboardOptions = KeyboardOptions.Default,
    keyboardActions: KeyboardActions = KeyboardActions.Default,
    singleLine: Boolean = false,
    minLines: Int,
    maxLines: Int = Int.MAX_VALUE,
    interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
    shape: Shape = MaterialTheme.shapes.small,
    colors: TextFieldColors = TextFieldDefaults.outlinedTextFieldColors()
) {
    val heightState = remember { mutableStateOf<Int?>(null) }
    var heightUpdateNeeded by remember(modifier, textStyle) { mutableStateOf(true) }
    val height = with(LocalDensity.current) {
        heightState.value?.toDp()
    } // to use if nullable unwrapping
    Box(modifier.height(IntrinsicSize.Min).width(IntrinsicSize.Min)) {
        if (heightUpdateNeeded) {
            OutlinedTextField(
                value = value + "\n".repeat(minLines),
                onValueChange = onValueChange,
                enabled = enabled,
                readOnly = readOnly,
                textStyle = textStyle,
                label = label,
                placeholder = placeholder,
                leadingIcon = leadingIcon,
                trailingIcon = trailingIcon,
                isError = isError,
                visualTransformation = visualTransformation,
                keyboardOptions = keyboardOptions,
                keyboardActions = keyboardActions,
                singleLine = singleLine,
                maxLines = maxLines,
                interactionSource = interactionSource,
                shape = shape,
                colors = colors,
                modifier = Modifier
                    .fillMaxSize()
                    .alpha(0f)
                    .onSizeChanged {
                        heightUpdateNeeded = false
                        println("onSizeChanged $it")
                        heightState.value = it.height
                    }
            )
        }
        if (height != null) {
            OutlinedTextField(
                value = value,
                onValueChange = onValueChange,
                enabled = enabled,
                readOnly = readOnly,
                textStyle = textStyle,
                label = label,
                placeholder = placeholder,
                leadingIcon = leadingIcon,
                trailingIcon = trailingIcon,
                isError = isError,
                visualTransformation = visualTransformation,
                keyboardOptions = keyboardOptions,
                keyboardActions = keyboardActions,
                singleLine = singleLine,
                maxLines = maxLines,
                interactionSource = interactionSource,
                shape = shape,
                colors = colors,
                modifier = Modifier
                    .fillMaxWidth()
                    .height(height)
            )
        }
    }
}