Jetpack Compose is Android’s modern toolkit for building native UIs with Kotlin. It simplifies UI development by using a declarative approach, meaning developers describe the UI in code and let the system handle the rest. Over the last few years, Jetpack Compose has become increasingly popular for building Android apps due to its flexibility, expressiveness, and seamless integration with other Android libraries.

In this blog post, we’ll dive deep into the Jetpack Compose core components, including the Compose Compiler Plugin, Compose Runtime, Compose UI Core, Compose UI Foundation, and Compose UI Material. Understanding these components is essential for building powerful and efficient Android applications with Jetpack Compose.

Jetpack Compose Core Components

Jetpack Compose core components include:

• Compose Compiler Plugin: Optimizes @Composable functions.
• Compose Runtime: Manages state and recomposition.
• Compose UI Core: Provides basic UI building blocks and modifiers.
• Compose UI Foundation: Adds common UI components and layouts.
• Compose UI Material: Delivers Material Design components.

These components work together to streamline UI development in Android.

Jetpack Compose Compiler Plugin

The Compose Compiler Plugin is responsible for transforming your composable functions into efficient, optimized code that can be executed by the Android platform.

Library Name: androidx.compose.compiler:compiler

Key Functions:

• Annotation Processing: The compiler recognizes @Composable functions and processes them accordingly.
• Code Transformation: It converts your composable functions into code that builds and manages the UI tree.
• Performance Optimization: By detecting changes in state, the compiler minimizes unnecessary recompositions to enhance efficiency.

How It Works:

When you mark a function with @Composable, the compiler plugin generates code that keeps track of the composable’s state and recomposition needs. This transformation allows Jetpack Compose to understand which parts of the UI need to be updated when data changes, ensuring efficient UI rendering.

Compose Runtime

The Compose Runtime is the engine that powers state management and recomposition in Jetpack Compose.

Library Name: androidx.compose.runtime:runtime

Core Responsibilities:

• State Management: It handles the state of composables and ensures that when data changes, only the affected parts of the UI are recomposed.
• Recomposition: The runtime efficiently updates the UI by re-rendering only what has changed, rather than the entire screen.
• UI Diffing: It compares the previous and current states to determine the minimal set of updates needed.

How It Works:

The runtime creates and maintains a tree structure of composables. When a composable’s state changes, the runtime selectively recomposes that part of the tree, making updates efficient and smooth.

Compose UI Core

The Compose UI Core library provides the essential building blocks for creating and arranging your UI components.

Library Name: androidx.compose.ui:ui

Key Elements:

• Layouts: Fundamental composables like Row, Column, Box, and ConstraintLayout help you organize UI elements.
• Modifiers: These allow you to adjust the appearance and behavior of composables. For example, you can apply padding, size adjustments, or click interactions using Modifier.padding() or Modifier.clickable().
• Drawing Tools: The core library supports custom graphics and drawing operations through APIs like Canvas.

How It Works:

Compose UI Core offers composables and modifiers that you can combine to create complex UIs. Modifiers are chainable, allowing you to apply multiple changes to a composable in a flexible way.

Compose UI Foundation

The Compose UI Foundation library builds on UI Core and provides commonly used UI elements and utilities for more interactive and polished interfaces.

Library Name: androidx.compose.foundation:foundation

Key Components:

• Text: Display text with customizable styles and formatting.
• Images: Render images from resources or assets.
• Specialized Layouts: Components like ConstraintLayout and BoxWithConstraints offer advanced layout options.
• Gesture Support: Built-in support for handling gestures like taps, drags, and swipes.

How It Works:

UI Foundation components are higher-level building blocks that simplify common UI tasks. For example, Text and Image are easy-to-use composables that can be styled and customized to suit your needs.

Compose UI Material

The Compose UI Material library brings Material Design components to Jetpack Compose, helping you build apps that follow Google’s design guidelines.

Library Name: androidx.compose.material3:material3

Key Components:

• Buttons: Standard Material buttons like Button, OutlinedButton, and IconButton.
• Cards: Card composables for grouping related content.
• Dialogs: Pre-built dialogs like AlertDialog for user interactions.
• Text Fields: Customizable input fields for user data.
• Theming: Built-in support for theming, allowing you to define colors, typography, and shapes.

How It Works:

Compose Material builds on the core and foundation libraries to provide ready-to-use components that align with Material Design principles. These components are customizable, allowing you to adapt them to your app’s branding.

Conclusion

Jetpack Compose revolutionizes Android UI development by providing a modern, declarative approach. Here’s a quick recap of the core components:

• Compose Compiler Plugin: Transforms @Composable functions into optimized code.
• Compose Runtime: Manages state and ensures efficient recomposition.
• Compose UI Core: Provides essential UI building blocks and modifiers.
• Compose UI Foundation: Adds common UI components and layout tools.
• Compose UI Material: Delivers Material Design components for a polished UI.

With Jetpack Compose, you can build flexible, maintainable, and high-performance UIs more easily than ever before. Whether you’re a beginner or an experienced developer, adopting Compose can significantly improve your Android development workflow.

happy UI composing..!