Book Image

Android Programming with Kotlin for Beginners

By : John Horton
5 (1)
Book Image

Android Programming with Kotlin for Beginners

5 (1)
By: John Horton

Overview of this book

Android is the most popular mobile operating system in the world and Kotlin has been declared by Google as a first-class programming language to build Android apps. With the imminent arrival of the most anticipated Android update, Android 10 (Q), this book gets you started building apps compatible with the latest version of Android. It adopts a project-style approach, where we focus on teaching the fundamentals of Android app development and the essentials of Kotlin by building three real-world apps and more than a dozen mini-apps. The book begins by giving you a strong grasp of how Kotlin and Android work together before gradually moving onto exploring the various Android APIs for building stunning apps for Android with ease. You will learn to make your apps more presentable using different layouts. You will dive deep into Kotlin programming concepts such as variables, functions, data structures, Object-Oriented code, and how to connect your Kotlin code to the UI. You will learn to add multilingual text so that your app is accessible to millions of more potential users. You will learn how animation, graphics, and sound effects work and are implemented in your Android app. By the end of the book, you will have sound knowledge about significant Kotlin programming concepts and start building your own fully featured Android apps.
Table of Contents (33 chapters)
Android Programming with Kotlin for Beginners
Contributors
Preface
Index

Creating bitmap graphics with the Bitmap class


Let's examine a bit of theory before we dive into the code and consider exactly how we are going to draw images to the screen. To draw a bitmap graphic, we will use the drawBitmap function of the Canvas class.

First, we will need to add a bitmap graphic to the project in the res/drawable folder – we will do this in reality in the Bitmap demo app later. For now, assume that the graphics file/bitmap has a name of myImage.png.

Next, we will declare an object of the Bitmap type in the same way that we did for the Bitmap object that we used for our background in the previous demo.

Next, we will need to initialize the myBitmap instance using our preferred image file, which we previously added to the project's drawable folder:

myBitmap = BitmapFactory.decodeResource
                (resources, R.drawable.myImage)

The decodeResource function of the BitmapFactory class is used to initialize myBitmap. It takes two parameters; the first is the resources property...