Android中无法获取Insets求助：如何获取摄像头刘海的Insets值？

一、通过WindowInsetsCompat监听系统Insets回调 #

首先确保Activity已开启全屏布局，取消系统自动布局适配：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    // 开启全屏，让布局延伸到刘海区域
    window.setDecorFitsSystemWindows(false)
    window.insetsController?.apply {
        systemBarsBehavior = WindowInsetsController.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
        hide(WindowInsetsCompat.Type.systemBars())
    }

    // 监听WindowInsets变化，获取DisplayCutout值
    ViewCompat.setOnApplyWindowInsetsListener(findViewById(android.R.id.content)) { _, insets ->
        val cutoutInsets = insets.getInsets(WindowInsetsCompat.Type.displayCutout())
        // 此处即可取到日志中的88px左侧刘海偏移量
        Log.d("CutoutInfo", "Left: ${cutoutInsets.left}, Top: ${cutoutInsets.top}")
        insets
    }
}

关键：必须设置window.setDecorFitsSystemWindows(false)，否则系统会自动将布局限制在安全区域，导致Insets被消费无法获取真实值。

二、Jetpack Compose中获取DisplayCutout #

使用Compose内置的Insets API，结合状态监听：

@Composable
fun FullScreenDrawing() {
    // 开启Edge-to-Edge模式，让布局延伸到系统栏/刘海区域
    enableEdgeToEdge()

    val windowInsets = rememberWindowInsets(WindowInsetsCompat.Type.displayCutout())
    val cutoutInsets = remember {
        derivedStateOf {
            windowInsets.getInsets(LocalWindow.current)
        }
    }

    // 监听Insets变化
    LaunchedEffect(cutoutInsets.value) {
        Log.d("ComposeCutout", "Left Offset: ${cutoutInsets.value.left}")
    }

    Box(modifier = Modifier.fillMaxSize()) {
        // 绘制Bitmap时，用cutoutInsets.value.left调整偏移量
        Canvas(modifier = Modifier.fillMaxSize()) {
            drawBitmap(
                bitmap = yourBitmap,
                topLeft = Offset(cutoutInsets.value.left.toFloat(), 0f)
            )
        }
    }
}

注意：需依赖最新版androidx.compose.foundation:foundation库，确保Insets API兼容性。

三、兜底：监听配置变化广播 #

若上述方法仍无法捕获，可通过系统广播监听配置变更，重新获取Insets：

private val configChangeReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        if (intent?.action == Intent.ACTION_CONFIGURATION_CHANGED) {
            val insets = WindowInsetsCompat.toWindowInsetsCompat(window.decorView.rootWindowInsets)
            val cutoutInsets = insets.getInsets(WindowInsetsCompat.Type.displayCutout())
            Log.d("CutoutOnConfig", "Left: ${cutoutInsets.left}")
        }
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    registerReceiver(configChangeReceiver, IntentFilter(Intent.ACTION_CONFIGURATION_CHANGED))
}

override fun onDestroy() {
    super.onDestroy()
    unregisterReceiver(configChangeReceiver)
}

该方法可应对部分机型刘海动态显示/隐藏的场景。

内容的提问来源于stack exchange，提问作者confused