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Building Android UIs with Custom Views
Building Android UIs with Custom Views

Building Android UIs with Custom Views: Build amazing custom user interfaces with Android custom views

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Paperback Oct 2017 294 pages 1st Edition
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Paperback Oct 2017 294 pages 1st Edition
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Can$34.98 Can$49.99
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Can$34.98 Can$49.99
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Can$61.99
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Building Android UIs with Custom Views

Implementing Your First Custom View

In the previous chapter, we've seen how to create the foundations of a custom view, but unless we add some more features and customizations it'll be pretty useless. In this chapter, we'll continue building on top of these foundations, see how we can parameterize our custom view to allow either ourselves or any other developer to customize them, and at the end, cover some rendering that will enable us to build slightly more complex custom views.

In addition, as we've mentioned in the previous chapter, we can create custom layouts as well. In this chapter, we'll see how to create a simple custom layout.

In more detail, we'll cover the following topics:

  • Measuring and parameterizing our custom view
  • Instantiating custom views
  • Creating custom layouts
  • Basic rendering

Measuring and parameterizing our custom view

In order to have a good reusable custom view, it needs to be able to adapt to different sizes and device resolutions, and to increase its reusability even more it should support parameterization.

Measuring our custom view

In the quick example we built in the previous chapter, we delegated all sizes and measurement to the parent view itself. To be honest, we haven't even delegated it; we just didn't do anything specifically to take care of that. Being able to control the size and dimensions of our custom view is something we definitely need to pay some attention to. To start, we're going to override the onMeasure() method from view as follows:

@Override 
protected...

Instantiating custom views

Now that we've seen how to set parameters on the XML layout and parse them on our custom view class, we'll see how to instantiate custom views from code as well and reuse then as much as possible from both instantiation mechanisms.

Instantiating custom views from code

On our custom view, we've created a single constructor with two parameters, a Context and an AttributeSet. Now, if we're creating our UI programmatically, or if by any other reason we need to instantiate our custom view by code, we need to create an additional constructor.

As we want to keep using our custom view in our XML layouts, we have to keep both constructors. To code avoid duplication, we will create some...

Creating a custom layout

Android provides several layouts to position our views in many different ways, but if these standard layouts aren't useful for our specific use case, we can create our own layouts.

Extending ViewGroup

The process to create a custom layout is quite similar to creating a custom view. We've got to create a class that extends from ViewGroup instead of view, create the appropriate constructors, implement the onMeasure() method, and override the onLayout() method rather than the onDraw() method.

Let's create a very simple custom layout; it will add elements to the right of the previous element until it doesn't fit on the screen, then it'll start a new row, using the higher element...

Basic rendering

So far we've only been drawing a solid background or a linear gradient. That's neither exciting nor really useful. Let's see how we can draw more interesting shapes and primitives. We'll do so by creating an example of a circular activity indicator that we'll be adding more and more features to in the following chapters.

Creating the basic circular activity indicator

The Canvas class provides us with many drawing functions; for example:

  • drawArc()
  • drawBitmap()
  • drawOval()
  • drawPath()

To draw a circular activity indicator, we can use the drawArc() method. Let's create the basic class and draw an arc:

public class CircularActivityIndicator extends View { 
    private static final...

Summary

In this chapter, we have seen how to measure and how to add parameters to our custom view. We also saw how to instantiate a custom view from code and use a Builder pattern to simplify all the parameters and keep our code cleaner. In addition, we went through a quick example of a custom layout and we started building a circular activity indicator. In the next chapter, we will see how to handle events and add some interactions to the circular activity indicator we've just started to build.

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Key benefits

  • Move beyond default UI templates, create and customize amazing UIs with Android Custom View
  • Enable smooth data flow and create futuristic UIs by creating flexible custom views
  • Scale your apps with responsive and data intensive views

Description

To build great user interfaces for your Android apps that go beyond the standard UI elements, you need to use custom Android views. With these, you can give your app a distinctive look and ensure that it functions properly across multiple devices. This book will help you construct a great UI for your apps by teaching you how to create custom Android views. You will start by creating your first Android custom view and go through the design considerations. You will then see how the right choices will enable your custom view to perform seamlessly across multiple platforms and Android versions. You will create custom styleable attributes that work with Android XML layouts, learn to process touch events, define custom attributes, and add properties and events to them. By the end of this book, you will be able to create apps with custom views that are responsive and adaptable to make your app distinctive and an instant hit with its users.

Who is this book for?

This book is for Android developers who want to create great user interfaces and move beyond the basics of the standard UI elements. They must have basic Android development knowledge along with basic Java programming.

What you will learn

  • Extend the standard UI widget framework by creating Custom views
  • Add complex rendering, animations, and interactions to your views
  • Optimize performance and decrease battery usage
  • Implement custom views to share between multiple projects, or share it publicly
  • Create 3D custom views using OpenGL ES

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Oct 27, 2017
Length: 294 pages
Edition : 1st
Language : English
ISBN-13 : 9781785882869
Vendor :
Google
Category :
Languages :
Tools :

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Product Details

Publication date : Oct 27, 2017
Length: 294 pages
Edition : 1st
Language : English
ISBN-13 : 9781785882869
Vendor :
Google
Category :
Languages :
Tools :

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Table of Contents

11 Chapters
Getting Started Chevron down icon Chevron up icon
Implementing Your First Custom View Chevron down icon Chevron up icon
Handling Events Chevron down icon Chevron up icon
Advanced 2D Rendering Chevron down icon Chevron up icon
Introducing 3D Custom Views Chevron down icon Chevron up icon
Animations Chevron down icon Chevron up icon
Performance Considerations Chevron down icon Chevron up icon
Sharing Our Custom View Chevron down icon Chevron up icon
Implementing Your Own EPG Chevron down icon Chevron up icon
Building a Charts Component Chevron down icon Chevron up icon
Creating a 3D Spinning Wheel Menu Chevron down icon Chevron up icon
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