Android Programming: The Big Nerd Ranch Guide, 4th Edition

Creating a Custom View

Android provides many excellent standard views and widgets, but sometimes you need a custom view that presents visuals that are unique to your app.

While there are all kinds of custom views, you can shoehorn them into two broad categories:

simple	A simple view may be complicated inside; what makes it “simple” is that it has no child views. A simple view will almost always perform custom rendering.
composite	Composite views are composed of other view objects. Composite views typically manage child views but do not perform custom rendering. Instead, rendering is delegated to each child view.

There are three steps to follow when creating a custom view:

1. Pick a superclass. For ...