Book Image

Android UI Development with Jetpack Compose

By : Thomas Künneth
Book Image

Android UI Development with Jetpack Compose

By: Thomas Künneth

Overview of this book

Jetpack Compose is Android’s new framework for building fast, beautiful, and reliable native user interfaces. It simplifies and significantly accelerates UI development on Android using the declarative approach. This book will help developers to get hands-on with Jetpack Compose and adopt a modern way of building Android applications. The book is not an introduction to Android development, but it will build on your knowledge of how Android apps are developed. Complete with hands-on examples, this easy-to-follow guide will get you up to speed with the fundamentals of Jetpack Compose such as state hoisting, unidirectional data flow, and composition over inheritance and help you build your own Android apps using Compose. You'll also cover concepts such as testing, animation, and interoperability with the existing Android UI toolkit. By the end of the book, you'll be able to write your own Android apps using Jetpack Compose.
Table of Contents (16 chapters)
Part 1:Fundamentals of Jetpack Compose
Part 2:Building User Interfaces
Part 3:Advanced Topics

Creating custom layouts

Sometimes, you may want to lay children out one after another in a row and start a new row when the current one has been filled. The CustomLayoutDemo sample app, as shown in the following screenshot, shows you how to do this. It creates 43 randomly colored boxes that vary in width and height:

Figure 4.4 – Sample CustomLayoutDemo app

Let's start by looking at the composable function that creates colored boxes:

fun ColoredBox() {
    modifier = Modifier
        width = 2.dp,
        color = Color.Black
      .width((40 * randomInt123()).dp)
      .height((10 * randomInt123()).dp)