Now that the project is setup you can start creating custom controls and states for them. This will all be inside the library project. Firstly you need to create an attributes xml file in values/attrs.xml (the name has to be attrs.xml) and adding the state:
In this tutorial we'll create a custom View called HorizontalSlider based on ProgressBar. This slider will allow the user to move the slider back and forth on the screen and get notified when this happens.