Book Image

Xamarin Mobile Development for Android Cookbook

By : Matthew Leibowitz
Book Image

Xamarin Mobile Development for Android Cookbook

By: Matthew Leibowitz

Overview of this book

Xamarin is used by developers to write native iOS, Android, and Windows apps with native user interfaces and share code across multiple platforms not just on mobile devices, but on Windows, Mac OS X, and Linux. Developing apps with Xamarin.Android allows you to use and re-use your code and your skills on different platforms, making you more productive in any development. Although it’s not a write-once-run-anywhere framework, Xamarin provides native platform integration and optimizations. There is no middleware; Xamarin.Android talks directly to the system, taking your C# and F# code directly to the low levels. This book will provide you with the necessary knowledge and skills to be part of the mobile development era using C#. Covering a wide range of recipes such as creating a simple application and using device features effectively, it will be your companion to the complete application development cycle. Starting with installing the necessary tools, you will be guided on everything you need to develop an application ready to be deployed. You will learn the best practices for interacting with the device hardware, such as GPS, NFC, and Bluetooth. Furthermore, you will be able to manage multimedia resources such as photos and videos captured with the device camera, and so much more! By the end of this book, you will be able to create Android apps as a result of learning and implementing pro-level practices, techniques, and solutions. This book will ascertain a seamless and successful app building experience.
Table of Contents (20 chapters)
Xamarin Mobile Development for Android Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Handling high-resolution images


Working with images often requires the app to be able to load very large images. Photos are especially large due to modern cameras producing high resolution images from excellent camera hardware.

How to do it...

We can easily load images from files, resources, or remote sources using the BitmapFactory type:

  1. All we need in order to load a bitmap is the path or stream and one of the decode methods, such as DecodeStreamAsync:

    using (var stream = Assets.Open("bigimage.png"))
    using (var bitmap = await BitmapFactory.DecodeStreamAsync(stream)) {
      imageView.SetImageBitmap(bitmap);
    }

As images can be quite large, both in resolution and in memory size, it is often better to reduce them using subsampling:

  1. When using subsampling, we need to provide extra options to the decode methods. This requires the use of the BitmapFactory.Options type:

    var options = new BitmapFactory.Options();
  2. Once we have the options, we can set various properties. If we want to load just the dimensions...