Building a basic chart custom view

Most probably, at one point or another, we'll have to draw some charts in an Android application. It can be a static chart, which isn't that fun as it can be replaced simply by an image, or it can be a dynamic chart, allowing user interactions and reactions to data changes. This last case is where we can use a custom view to draw real-time graphs, add multiple sources of data, and even animate it. Let's start by building a very simple custom view where we'll add more features later on.

Margins and padding

As with any normal view, our custom view will be subject to the layout manager's margins and to the view's padding. We should not worry that much about the...