How to Create Custom Typography in Jetpack Compose

Jetpack Compose has revolutionized Android development, offering a modern, declarative approach to UI design. One of its standout features is the ability to customize every aspect of your app's appearance, including typography. Typography plays a vital role in defining an app's visual identity and user experience. In this blog post, we’ll explore how to create custom typography in Jetpack Compose, focusing on advanced concepts, best practices, and practical use cases.

Why Custom Typography Matters

Typography is more than just choosing fonts; it’s about creating a cohesive visual language that enhances readability, accessibility, and branding. By customizing typography in Jetpack Compose, you can:

  • Reinforce brand identity with unique fonts and styles.

  • Improve readability across different devices and screen sizes.

  • Enhance accessibility by adjusting font sizes and weights dynamically.

  • Create a visually appealing and consistent user interface.

Understanding Typography in Jetpack Compose

Jetpack Compose uses Typography to define text styles across your app. The Typography class provides a set of predefined text styles, such as h1, body1, and caption. These styles are customizable and can be applied globally through the MaterialTheme.

Default Typography in Jetpack Compose

Here’s an example of the default Typography provided by Compose:

val Typography = Typography(
    h1 = TextStyle(
        fontWeight = FontWeight.Bold,
        fontSize = 30.sp,
        letterSpacing = 0.25.sp
    ),
    body1 = TextStyle(
        fontWeight = FontWeight.Normal,
        fontSize = 16.sp,
        letterSpacing = 0.5.sp
    ),
    caption = TextStyle(
        fontWeight = FontWeight.Light,
        fontSize = 12.sp,
        letterSpacing = 0.4.sp
    )
)

While these defaults are sufficient for many applications, creating a unique look often requires customization.

Step-by-Step Guide to Custom Typography

1. Define Your Custom Font Resources

Start by adding custom fonts to your project. Place the font files in the res/font directory (e.g., res/font/roboto_bold.ttf). Update your build.gradle file to include font support:

android {
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = "1.x.x"
    }
}

2. Create a Font Family

Use the FontFamily class to define your custom fonts:

val RobotoFontFamily = FontFamily(
    Font(R.font.roboto_regular, FontWeight.Normal),
    Font(R.font.roboto_bold, FontWeight.Bold),
    Font(R.font.roboto_italic, FontWeight.Italic)
)

3. Define Custom Text Styles

Create a new Typography instance with custom text styles:

val CustomTypography = Typography(
    h1 = TextStyle(
        fontFamily = RobotoFontFamily,
        fontWeight = FontWeight.Bold,
        fontSize = 34.sp
    ),
    body1 = TextStyle(
        fontFamily = RobotoFontFamily,
        fontWeight = FontWeight.Normal,
        fontSize = 16.sp
    ),
    caption = TextStyle(
        fontFamily = RobotoFontFamily,
        fontWeight = FontWeight.Light,
        fontSize = 12.sp
    )
)

4. Apply Custom Typography to MaterialTheme

To apply your custom typography, wrap your composables with a MaterialTheme that uses your CustomTypography:

MaterialTheme(
    typography = CustomTypography
) {
    // Your composables here
}

5. Use Text Composables with Custom Styles

To use your custom typography, apply text styles to Text composables:

Text(
    text = "Hello, World!",
    style = MaterialTheme.typography.h1
)

Advanced Typography Techniques

Dynamic Font Scaling

Ensuring readability on devices with varying screen sizes and densities is crucial. Use TextUnit with sp (scalable pixels) to create text sizes that adjust dynamically:

Text(
    text = "Responsive Text",
    style = TextStyle(fontSize = 18.sp)
)

Themed Typography

Leverage themes to provide different typography styles for light and dark modes:

val LightTypography = Typography(
    h1 = TextStyle(
        fontFamily = RobotoFontFamily,
        fontWeight = FontWeight.Bold,
        fontSize = 34.sp,
        color = Color.Black
    )
)

val DarkTypography = Typography(
    h1 = TextStyle(
        fontFamily = RobotoFontFamily,
        fontWeight = FontWeight.Bold,
        fontSize = 34.sp,
        color = Color.White
    )
)

MaterialTheme(
    typography = if (isSystemInDarkTheme()) DarkTypography else LightTypography
) {
    // Your composables here
}

Custom Font Loading at Runtime

For apps requiring runtime font customization (e.g., user-selected fonts), use FontFamily.Resolver to load fonts dynamically:

val dynamicFont = FontFamilyResolver().resolve(
    Font("url-to-font.ttf", FontWeight.Normal)
)

Text(
    text = "Dynamic Font",
    style = TextStyle(fontFamily = dynamicFont)
)

Animating Text Appearance

Combine Typography with animations to create engaging text transitions:

val animatedSize by animateDpAsState(targetValue = 34.dp)

Text(
    text = "Animated Text",
    style = TextStyle(fontSize = animatedSize)
)

Best Practices for Custom Typography

  1. Consistency: Maintain uniform font styles across your app to enhance usability and branding.

  2. Accessibility: Use TextUnit with sp and respect user preferences for font scaling.

  3. Performance: Optimize font resources and avoid overloading the app with too many custom fonts.

  4. Testing: Test typography on multiple screen sizes and resolutions to ensure readability.

Conclusion

Custom typography in Jetpack Compose empowers developers to create visually appealing, accessible, and brand-consistent Android applications. By defining custom fonts, styles, and themes, you can elevate your app’s design and user experience. Apply the best practices and advanced techniques shared in this post to master typography in Jetpack Compose.