Advanced Compose | Jetpack Compose | Android Development Tutorial

Introduction

Jetpack Compose is Android's modern toolkit for building native UI. It simplifies and accelerates UI development on Android with less code, powerful tools, and intuitive Kotlin APIs. In this tutorial, we will delve into advanced concepts in Jetpack Compose to build dynamic and complex UI applications.

State Management

Managing state in Jetpack Compose is crucial for building interactive and dynamic UIs. State management involves how your composables handle and respond to different states over time.

Example: Simple State Management

@Composable
fun Counter() {
    var count by remember { mutableStateOf(0) }

    Column(
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center
    ) {
        Text("Count: $count")
        Button(onClick = { count++ }) {
            Text("Increment")
        }
    }
}

Layouts and Modifiers

Compose provides a set of composables that are pre-defined layout elements, such as Column, Row, and Box. Modifiers allow you to decorate or augment these layouts with behavior and attributes.

Example: Complex Layout

@Composable
fun ComplexLayout() {
    Column(
        modifier = Modifier
            .fillMaxSize()
            .padding(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.spacedBy(8.dp)
    ) {
        Text("Title", style = MaterialTheme.typography.h4)
        Row(
            modifier = Modifier.fillMaxWidth(),
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Text("Left")
            Text("Right")
        }
        Box(
            modifier = Modifier
                .size(100.dp)
                .background(Color.Blue)
        ) {
            Text("Inside Box", color = Color.White, modifier = Modifier.align(Alignment.Center))
        }
    }
}

Theming and Styling

Theming in Jetpack Compose is done using Material Design principles. You can customize themes to fit your application's brand and style.

Example: Custom Theme

private val DarkColorPalette = darkColors(
    primary = Color(0xFF1EB980),
    primaryVariant = Color(0xFF045D56),
    secondary = Color(0xFF03DAC6)
)

private val LightColorPalette = lightColors(
    primary = Color(0xFF6200EE),
    primaryVariant = Color(0xFF3700B3),
    secondary = Color(0xFF03DAC6)
)

@Composable
fun CustomTheme(content: @Composable () -> Unit) {
    val colors = if (isSystemInDarkTheme()) {
        DarkColorPalette
    } else {
        LightColorPalette
    }

    MaterialTheme(
        colors = colors,
        typography = Typography,
        shapes = Shapes,
        content = content
    )
}

Animation

Animations in Jetpack Compose are straightforward and expressive. You can create simple or complex animations using various Compose APIs.

Example: Simple Animation

@Composable
fun SimpleAnimation() {
    var isVisible by remember { mutableStateOf(true) }
    val alpha: Float by animateFloatAsState(if (isVisible) 1f else 0f)

    Column(
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
        modifier = Modifier.fillMaxSize()
    ) {
        Button(onClick = { isVisible = !isVisible }) {
            Text("Toggle Visibility")
        }
        Spacer(modifier = Modifier.height(16.dp))
        Text("Animated Text", modifier = Modifier.alpha(alpha))
    }
}

Interoperability

Jetpack Compose can interoperate with existing Android Views, allowing you to gradually adopt Compose in your existing projects.

Example: Using Compose in XML

And in your Activity or Fragment:

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

        findViewById(R.id.customComposeView).setContent {
            Text("Hello from Compose!")
        }
    }
}

Advanced Compose - Jetpack Compose