Integrating traditional Android views with Jetpack Compose can create a versatile UI experience, blending the robustness of classic views with the modern capabilities of Compose. However, this integration can introduce lifecycle and performance challenges. In this blog post, we’ll explore these challenges and provide strategies to manage them effectively, supported by Kotlin code examples.

Why Combine Traditional Views with Jetpack Compose?

Jetpack Compose simplifies UI development with its declarative approach, but many existing projects are built with traditional XML-based views. Combining both allows developers to leverage the strengths of each toolkit.

Industrial Use Cases for Mixing Views:

1. Incremental Migration: Gradually migrate existing XML-based screens to Compose to reduce risk and disruption.
2. Complex Components: Use traditional views for complex components like WebView or MapView that lack full Compose support.
3. Third-Party Libraries: Utilize third-party libraries that rely on traditional views while integrating Compose for new features.
4. Performance Optimization: Apply traditional views where Compose may not yet be optimized for specific tasks.
5. Hybrid App Architectures: Maintain compatibility between modules developed with different toolkits in modular architectures.

Common Lifecycle and Performance Issues

1. Lifecycle Mismatches: Different lifecycle management strategies between Compose and traditional views can lead to rendering and resource management issues.
2. State Management: Synchronizing state between Compose and traditional views can be tricky, potentially causing inconsistent UI states.
3. Performance Overheads: Wrapping views can introduce performance overheads, including jank and latency.
4. Input Events Handling: Proper propagation of touch and input events between views may be problematic.

Scenario 1: Using a Traditional View Inside a Jetpack Compose UI

Problem Statement: You want to integrate a MapView within a Compose layout but encounter issues with state retention during navigation.

Code Example: Using AndroidView in Compose

@Composable
fun MapScreen() {
    // State to handle lifecycle events
    val lifecycleOwner = LocalLifecycleOwner.current

    // MapView initialized inside a Composable function
    AndroidView(
        factory = { context ->
            MapView(context).apply {
                // Handle lifecycle manually
                lifecycleOwner.lifecycle.addObserver(object : DefaultLifecycleObserver {
                    override fun onResume(owner: LifecycleOwner) {
                        this@apply.onResume()
                    }

                    override fun onPause(owner: LifecycleOwner) {
                        this@apply.onPause()
                    }

                    override fun onDestroy(owner: LifecycleOwner) {
                        this@apply.onDestroy()
                    }
                })
            }
        },
        modifier = Modifier.fillMaxSize()
    )
}

Lifecycle Issue and Solution:

• Issue: MapView requires explicit lifecycle management, which Compose does not handle automatically.
• Solution: Use a LifecycleObserver to ensure MapView responds to lifecycle changes correctly.

Scenario 2: Embedding Compose in a Traditional View-Based UI

Problem Statement: Adding a Compose-based button to a legacy XML layout causes state reset issues on configuration changes.

Code Example: Using ComposeView in Traditional Layout

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <!-- Traditional views -->
    <TextView
        android:id="@+id/traditionalTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="This is a traditional TextView"/>

    <!-- Jetpack Compose view -->
    <androidx.compose.ui.platform.ComposeView
        android:id="@+id/composeView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

Setting up ComposeView in your Activity or Fragment:

 class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val composeView: ComposeView = findViewById(R.id.composeView)

        // Setting the Compose content dynamically
        composeView.setContent {
            ComposeButton()
        }
    }
}

@Composable
fun ComposeButton() {
    var count by rememberSaveable { mutableStateOf(0) }
    Button(onClick = { count++ }) {
        Text("Clicked $count times")
    }
}

              

Lifecycle and State Management Issue:

• Issue: ComposeView state might reset on configuration changes like screen rotation.
• Solution: Use rememberSaveable to preserve state through configuration changes.

Handling Input Events

Problem Statement: Touch events in traditional views might not function correctly when wrapped in Compose, leading to inconsistent user interactions.

Code Solution:

Ensure touch events are handled correctly in traditional views within Compose:

@Composable
fun GestureHandlingView() {
    AndroidView(factory = { context ->
        TextView(context).apply {
            text = "Swipe here"
            setOnTouchListener { _, event ->
                when (event.action) {
                    MotionEvent.ACTION_DOWN -> {
                        // Handle touch down
                    }
                    MotionEvent.ACTION_MOVE -> {
                        // Handle move
                    }
                    MotionEvent.ACTION_UP -> {
                        // Handle touch up
                    }
                }
                true
            }
        }
    })
}

Performance Optimization Tips

• Avoid Unnecessary Recompositions: Minimize unnecessary recompositions by using keys in Compose functions when embedding traditional views.
• Recycle Views Carefully: Ensure proper recycling of views within Compose to prevent memory leaks.
• Profile Performance: Use Android Studio Profiler to monitor performance and address any jank or latency issues.

Conclusion

Combining traditional views with Jetpack Compose can provide a powerful and flexible UI solution, but it requires careful management of lifecycle, state, and performance. By understanding and addressing these challenges, you can create seamless hybrid UIs that leverage the strengths of both toolkits. Stay tuned for more insights and tips on Android development by following.

This article is previously published on proandroiddev.com