Cannot access 'RowScopeInstance': it is internal in 'androidx.compose.foundation.layout'

Question

我试图实现以下布局

我尝试使用Row(Modifier.weight(50f))编译器开始抛出的错误

如果进口自ColumnInstance-import androidx.compose.foundation.layout.ColumnScopeInstance.weight

Cannot access 'ColumnScopeInstance': it is internal in 'androidx.compose.foundation.layout'

如果进口自RowInstance-androidx.compose.foundation.layout.RowScopeInstance.weight

Cannot access 'RowScopeInstance': it is internal in 'androidx.compose.foundation.layout'

下面附上我的可组合代码

@Composable
fun BoxLayout(){
    Row(Modifier.weight(50f)) {
        BoxWithText()
        BoxWithText()
    }
}

附上整个文件以供参考

package me.sanjaykapilesh.layoutmastery

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.RowScopeInstance.weight
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.tooling.preview.Preview
import me.sanjaykapilesh.layoutmastery.ui.theme.LayoutMasteryTheme

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            LayoutMasteryTheme {
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colors.background
                ) {
                    BoxWithText()
                }
            }
        }
    }
}



@Composable
fun BoxLayout(){
    Row(Modifier.weight(50f)) {
        BoxWithText()
        BoxWithText()
    }
}

@Composable
fun BoxWithText() {
    Column() {
        Text(text = "Hello Box!")
        Text(text = "Displays text and follows Material Design guidelines")
    }

}

@Preview(showBackground = true)
@Composable
fun BoxLayoutPreview() {
    LayoutMasteryTheme {
        BoxLayout()
    }
}

我不知道为什么我会收到错误。我也无法实现Modifier.weight

问题 - https://developer.android.com/codelabs/basic-android-kotlin-compose-composables-practice-problems?authuser=2&continue=https%3A%2F%2Fdeveloper.android.com%2Fcourses%2Fpathways%2Fandroid- basics-compose-unit-1-pathway-3%3Fauthuser%3D2%23codelab-https%3A%2F%2Fdeveloper.android.com%2Fcodelabs%2Fbasic-android-kotlin-compose-composables-practice-problems#3

Answer 1

您可以使用扩展函数来获取上下文。例如：

@Composable
fun ColumnScope.BoxLayout(){
    Row(Modifier.weight(50f)) {
        BoxWithText()
        BoxWithText()
    }
}

Answer 2

某些修饰符对于定义它们的作用域是唯一的，例如 Modifier.weight 默认情况下仅在 RowScope 或 ColumnScope 中可用。或者 Modifier.align 仅在 BoxScope 内可用。

当您希望访问这些修饰符时，您需要在这些范围内拥有可组合函数，或者创建一个带有这些范围的接收器的 @Composable 参数的函数

@Composable
fun BoxLayout(){
    Row(Modifier.weight(50f)) {
        BoxWithText()
        BoxWithText()
    }
}

BoxLayout 应返回 RowScope/ColumnScope，因为这样才能使用 Modifier.weight，并且可以这样做

@Composable
fun BoxWithLayout(content: @Composable RowScope.()->Unit){
    Row {
        content()
    }
}

@Composable
private fun Sample() {
   BoxWithLayout {
       Row(Modifier.weight(50f)) {
           BoxWithText()
           BoxWithText()
       }
   }
}

Answer 3

需要在任何行/列范围内调用权重参数。所以试试这个

 @Composable
    fun BoxLayout(){
       Row{
        Row(Modifier.weight(50f)) {
          BoxWithText()
          BoxWithText()
        }
      }  
    }