喷气背包撰写，使用自定义生命周期/视图模型存储/保存状态注册表所有者时不会触发重构

Question

我试图创建一个覆盖并将视图附加到WindowManager，我已经设法通过创建一个实现Lifecycle/ViewModelStore/SavedStateRegistry Owner的类来做到这一点。但出于某种原因，每当我试图用MutableState或MutableStateFlow来显示一个对话框或以任何方式改变UI时，重组都不会触发。

有没有人尝试过这样做，并设法找到一个解决方案来触发重组?

这是我试图创建和插入视图的方式:

@SuppressLint("InflateParams")
fun showOverlay() {
synchronized(lock) {
if (overlay != null || overlay?.parent != null) {
return
}
val viewModel = OverlayViewModel(context.applicationContext as Application)
var scope: CoroutineScope? = null
overlay = ComposeView(context).apply {
setContent {
Overlay(viewModel)
}
}
drawOverLifecycleOwner = DrawOverLifecycleOwner()
drawOverLifecycleOwner?.attachToDecorView(overlay)
val params =
WindowManager.LayoutParams(
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE or WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL or WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
PixelFormat.TRANSLUCENT
)
params.gravity = Gravity.TOP or Gravity.START
Log.i("ScreenLocker", "Inserting overlay")
ContextCompat.getMainExecutor(context).execute {
drawOverLifecycleOwner?.onCreate()
windowManager.addView(overlay, params)
}
}
}

这是自定义的LifecycleOwner:

import android.view.View
import androidx.lifecycle.*
import androidx.savedstate.SavedStateRegistry
import androidx.savedstate.SavedStateRegistryController
import androidx.savedstate.SavedStateRegistryOwner
import androidx.savedstate.ViewTreeSavedStateRegistryOwner
class DrawOverLifecycleOwner : LifecycleOwner, ViewModelStoreOwner, SavedStateRegistryOwner {
fun onCreate() {
savedStateRegistryController.performRestore(null)
lifecycleRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE)
}
fun onResume() {
lifecycleRegistry.handleLifecycleEvent(Lifecycle.Event.ON_RESUME)
}
fun onPause() {
lifecycleRegistry.handleLifecycleEvent(Lifecycle.Event.ON_PAUSE)
}
fun onDestroy() {
lifecycleRegistry.handleLifecycleEvent(Lifecycle.Event.ON_DESTROY)
savedStateRegistryController.performSave(Bundle())
store.clear()
}
/**
Compose uses the Window's decor view to locate the
Lifecycle/ViewModel/SavedStateRegistry owners.
Therefore, we need to set this class as the "owner" for the decor view.
*/
fun attachToDecorView(decorView: View?) {
if (decorView == null) return
ViewTreeLifecycleOwner.set(decorView, this)
ViewTreeViewModelStoreOwner.set(decorView, this)
ViewTreeSavedStateRegistryOwner.set(decorView, this)
}
// LifecycleOwner methods
private val lifecycleRegistry: LifecycleRegistry = LifecycleRegistry(this)
override fun getLifecycle(): Lifecycle = lifecycleRegistry
// ViewModelStore methods
private val store = ViewModelStore()
override fun getViewModelStore(): ViewModelStore = store
// SavedStateRegistry methods
private val savedStateRegistryController = SavedStateRegistryController.create(this)
override val savedStateRegistry: SavedStateRegistry
get() = savedStateRegistryController.savedStateRegistry
}

这是叠加:

@Composable
fun Overlay(viewModel: OverlayViewModel = viewModel()) {
val showDialog = remember { MutableStateFlow(false) }
AppTheme {
Logger.info("Recomposition triggered")
ConstraintLayout(
modifier = Modifier
.fillMaxSize()
.background(Color.Black)
) {
val (dialog) = createRefs()
Box(modifier = Modifier.fillMaxSize()) {
Text(
modifier = Modifier
.align(Alignment.TopEnd)
.padding(top = 25.dp, end = 15.dp),
text = "© 2022",
color = Color.White
)
Column(
modifier = Modifier.align(Alignment.Center),
horizontalAlignment = Alignment.CenterHorizontally
) {
Image(
modifier = Modifier
.fillMaxWidth()
.padding(15.dp),
painter = painterResource(R.drawable.logo),
contentDescription = "Logo",
contentScale = ContentScale.Fit,
)
Text(
modifier = Modifier.padding(bottom = 25.dp),
text = "Overlay Text",
textAlign = TextAlign.Center,
color = Color.White,
fontWeight = FontWeight.Bold,
style = MaterialTheme.typography.headlineMedium
)
LazyRow {
items(LockService.whitelistedApps) { app ->
Button(
onClick = { viewModel.launchApp(app) },
colors = ButtonDefaults.buttonColors(
containerColor = Color.Transparent
)
) {
Column(horizontalAlignment = Alignment.CenterHorizontally) {
viewModel.getPackageIcon(app)?.apply {
Image(
this.asImageBitmap(),
contentDescription = "App Icon"
)
}
Text(
text = viewModel.getPackageLabel(app),
color = Color.White
)
}
}
}
}
}
IconButton(
modifier = Modifier
.align(Alignment.BottomStart)
.padding(bottom = 15.dp, start = 15.dp),
onClick = {
Logger.info("Trying to show dialog, showDialogValue = ${showDialog.value}")
showDialog.tryEmit(true)
}
) {
Icon(
imageVector = Icons.Default.Info,
contentDescription = "Info Dialog Icon",
tint = Color.White
)
}
}
if (showDialog.collectAsState().value) {
InfoDialog(showDialog, Modifier.constrainAs(dialog) {
top.linkTo(parent.top)
bottom.linkTo(parent.bottom)
start.linkTo(parent.start)
end.linkTo(parent.end)
})
}
}
}
}
@Preview
@Composable
fun OverlayPreview() {
AppTheme {
Overlay(OverlayViewModel(Application()))
}
}

Answer 1

嘿，我发现了我的实现中的问题，它可能和你的一样。

当你强制设置lifecycleOwner到ComposeView时，你是否也设置ON_START事件?在我的版本中，当我完成了可组合对象在到来时开始响应新状态时，它就丢失了。

val viewModelStore = ViewModelStore()
lifecycleOwner.performRestore(null)
lifecycleOwner.handleLifecycleEvent(Lifecycle.Event.ON_CREATE)
lifecycleOwner.handleLifecycleEvent(Lifecycle.Event.ON_START)
ViewTreeLifecycleOwner.set(composeView, lifecycleOwner)
ViewTreeViewModelStoreOwner.set(composeView) { viewModelStore }
it.setViewTreeSavedStateRegistryOwner(lifecycleOwner)