Build Custom Components with Jetpack Compose Material 3

Jetpack Compose has revolutionized Android development by offering a declarative approach to UI creation. With Material 3—the latest design system by Google—Compose allows developers to build stunning, modern interfaces that are both flexible and user-friendly. While Jetpack Compose provides a wide range of out-of-the-box Material 3 components, there are many scenarios where building custom components is necessary to meet unique design requirements. This blog dives deep into creating custom components with Jetpack Compose Material 3, catering to intermediate and advanced Android developers.

Why Custom Components?

Although Material 3 components are powerful and customizable, developers often face specific design challenges or unique requirements that prebuilt components can’t fully address. Here are a few reasons why creating custom components might be necessary:

  1. Brand-specific Design: Your app’s brand guidelines may require unique visuals.

  2. Enhanced Functionality: You might need interactions or animations that aren’t available in standard components.

  3. Reusable UI Elements: Custom components can streamline development and ensure consistent behavior across the app.

By leveraging Jetpack Compose’s composability and Material 3’s theming, you can craft components that fit seamlessly into your design system.

Setting the Stage: Prerequisites

Before diving into creating custom components, ensure you have:

  • A solid understanding of Jetpack Compose basics (e.g., Composable functions, State management).

  • Familiarity with Material 3 components and themes.

  • Android Studio Arctic Fox or later, with Compose dependencies set up in your project.

Here’s a quick reminder to add Material 3 dependencies to your build.gradle file:

dependencies {
    implementation "androidx.compose.material3:material3:1.1.0"
    implementation "androidx.compose.ui:ui:1.4.3"
    implementation "androidx.compose.ui:ui-tooling:1.4.3"
}

Understanding Material 3 Theming

Before creating custom components, it’s crucial to align them with your app’s theme. Material 3 introduces the M3 Design Tokens, including typography, color schemes, and shapes. These tokens ensure consistency across all components, including custom ones.

Defining a Theme

Start by configuring your Theme composable:

@Composable
fun MyAppTheme(content: @Composable () -> Unit) {
    val colorScheme = lightColorScheme(
        primary = Color(0xFF6200EE),
        secondary = Color(0xFF03DAC5),
        background = Color(0xFFF6F6F6),
        surface = Color(0xFFFFFFFF),
        onPrimary = Color.White,
        onSecondary = Color.Black
    )

    MaterialTheme(
        colorScheme = colorScheme,
        typography = Typography,
        content = content
    )
}

This theme will provide a consistent look and feel across your app, including your custom components.

Building a Custom Component

Example: Custom Badge with Dynamic Styles

Let’s create a CustomBadge component. This badge will:

  1. Display a dynamic count.

  2. Support different colors based on the count’s value.

  3. Use Material 3’s typography and shape system.

Here’s how to implement it:

@Composable
fun CustomBadge(
    count: Int,
    modifier: Modifier = Modifier,
    backgroundColor: Color = MaterialTheme.colorScheme.primary,
    textColor: Color = MaterialTheme.colorScheme.onPrimary
) {
    val dynamicBackground = when {
        count > 10 -> MaterialTheme.colorScheme.secondary
        count > 5 -> MaterialTheme.colorScheme.tertiary
        else -> backgroundColor
    }

    Box(
        modifier = modifier
            .background(dynamicBackground, shape = MaterialTheme.shapes.small)
            .padding(horizontal = 8.dp, vertical = 4.dp),
        contentAlignment = Alignment.Center
    ) {
        Text(
            text = "$count",
            style = MaterialTheme.typography.labelLarge,
            color = textColor
        )
    }
}

Usage Example

Add the CustomBadge to your UI:

@Composable
fun BadgeDemo() {
    Column(
        verticalArrangement = Arrangement.spacedBy(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        modifier = Modifier.fillMaxSize()
    ) {
        CustomBadge(count = 3)
        CustomBadge(count = 7)
        CustomBadge(count = 12, backgroundColor = Color.Red)
    }
}

This will render badges with dynamic colors and text based on the count.

Best Practices

  1. Modularity: Use parameters like Modifier and Color to ensure flexibility.

  2. Theme Integration: Leverage Material 3’s colorScheme and typography to maintain consistency.

  3. State Management: Use State for components requiring interactivity or animations.

Advanced Use Case: Animated Custom Button

Let’s create an animated button that changes color when clicked, incorporating Material 3’s design principles.

@Composable
fun AnimatedButton(
    onClick: () -> Unit,
    modifier: Modifier = Modifier,
    text: String = "Click Me",
    initialColor: Color = MaterialTheme.colorScheme.primary,
    clickedColor: Color = MaterialTheme.colorScheme.secondary
) {
    var isClicked by remember { mutableStateOf(false) }

    val buttonColor by animateColorAsState(
        targetValue = if (isClicked) clickedColor else initialColor,
        animationSpec = tween(durationMillis = 500)
    )

    Button(
        onClick = {
            isClicked = !isClicked
            onClick()
        },
        colors = ButtonDefaults.buttonColors(containerColor = buttonColor),
        modifier = modifier
    ) {
        Text(text = text)
    }
}

Usage Example

@Composable
fun AnimatedButtonDemo() {
    Column(
        verticalArrangement = Arrangement.spacedBy(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        modifier = Modifier.fillMaxSize()
    ) {
        AnimatedButton(
            onClick = { Log.d("AnimatedButton", "Button clicked") },
            text = "Tap Me"
        )
    }
}

Key Points

  • Animation: The animateColorAsState function makes it easy to add smooth transitions.

  • Interactivity: Use remember to maintain component state.

Testing and Debugging Custom Components

Testing is vital for reusable components. Use Compose’s testing framework to validate UI behavior:

@get:Rule
val composeTestRule = createComposeRule()

@Test
fun testCustomBadge() {
    composeTestRule.setContent {
        CustomBadge(count = 5)
    }

    composeTestRule
        .onNodeWithText("5")
        .assertExists()
        .assertIsDisplayed()
}

Debugging Tips

  • Use Modifier.debugInspectorInfo to inspect component properties.

  • Leverage Compose Preview for real-time UI adjustments.

Conclusion

Building custom components with Jetpack Compose Material 3 empowers developers to create unique, reusable, and brand-specific UI elements. By adhering to best practices, leveraging Material 3’s theming, and incorporating animations, you can craft components that elevate your app’s user experience.

Jetpack Compose continues to redefine Android development, making it easier than ever to innovate while maintaining consistency and efficiency. Start building your custom components today and unlock the full potential of Material 3!

What are your favorite tips or techniques for creating custom components in Jetpack Compose? Share your thoughts in the comments below!