更改创建它的参数后，如何替换Android Jetpack Compose AndroidView？

问题描述

我有一个应用程序，它显示封装在AndroidView中的几种不同视图。在下面要重现的简单示例中，这些只是TextView实例。问题在于更改文本（在这种情况下，通过三个不同的值循环）似乎并没有更新应用程序显示的内容。

sealed class AppView
data class ShowSomeText(val text: String) : AppView()
data class SomeOtherState(val data: Any?) : AppView()
data class ShowSomeText2(val text: String) : AppView()

class AppViewModel : ViewModel() {

    var currentView = MutableLiveData<AppView>(ShowSomeText("original text"))
    var currentViewWorkaround = MutableLiveData<AppView>(ShowSomeText("original text"))


    private val textRing = arrayOf("one","two","three")
    private var textRingPosition = 0

    fun incrementTextState() {
        val nextState = ShowSomeText(textRing[textRingPosition])
        currentView.postValue(nextState)

        val nextStateWorkaround = when(currentViewWorkaround.value) {
            is ShowSomeText -> ShowSomeText2(textRing[textRingPosition])
            else -> ShowSomeText(textRing[textRingPosition])
        }
        currentViewWorkaround.postValue(nextStateWorkaround)
        textRingPosition = (textRingPosition + 1) % textRing.size
    }
}

class MainActivity : AppCompatActivity() {

    private val viewModel = AppViewModel()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ViewContainer(viewModel)
        }
    }
}

@Composable
fun ViewContainer(viewModel: AppViewModel) {

    // Add this to gradle.build for the observeAsState function:
    //     implementation "androidx.compose.runtime:runtime-livedata:$compose_version"
    val currentView: AppView by viewModel.currentView.observeAsState(ShowSomeText("starting text"))
    val currentViewWorkaround: AppView by viewModel.currentViewWorkaround.observeAsState(ShowSomeText("starting text"))

    Column {
        Button(onClick = viewModel::incrementTextState) {
            Text(
                text = "tap to change",style = TextStyle(fontSize = 12.em)
            )
        }
        Text("Compose Text")
        when (currentView) {
            is ShowSomeText -> createComposeTextView((currentView as ShowSomeText).text)
            is SomeOtherState -> Text("the other state")
        }
        Text("AndroidView wrapping TextView")
        when (currentView) {
            is ShowSomeText -> createAndroidViewForTextView((currentView as ShowSomeText).text)
            is SomeOtherState -> Text("the other state")
        }
        Text("AndroidView wrapping TextView with 2-state workaround")
        when (currentViewWorkaround) {
            is ShowSomeText -> createAndroidViewForTextView((currentViewWorkaround as ShowSomeText).text)
            is ShowSomeText2 -> createAndroidViewForTextView((currentViewWorkaround as ShowSomeText2).text)
            is SomeOtherState -> Text("the other state")
        }
    }

}

@Composable
fun createAndroidViewForTextView(text: String) {
    val context = ContextAmbient.current
    val tv = remember(text,context) {
        val x = TextView(context)
        x.text = text
        x.textSize = 48.0f
        x
    }
    AndroidView({ tv })
}

@Composable
fun createComposeTextView(text: String) {
    Text(text,style = TextStyle(fontSize = 12.em))
}

第一个文本通过Compose Text函数显示并起作用，第二个文本带有TextView包装的AndroidView Compose函数并且不起作用，第三个也使用相同的AndroidView包装器，但通过使用另一个状态变量以某种方式触发了更改。

为什么中间文本不更新？

具有hack修复程序https://gist.github.com/okhobb/ba7791af4562ea672d0c52769a7cd8ba

的可复制kt文件的完整摘要

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

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