We have seen add-on buttons before. In this section, we will add a button class where all our code will be written. This button, which will have a GPS icon, will be the sole work in this chapter. Eventually, we want to click on this button and display a form to ask the user to select the GPS file, which has a list of previously recorded tracks of coordinates. Then we will parse this file, process each record individually, and display that particular point on the map. We will create a timer to fetch each coordinate every second so that we will be able to actually see the cell phone signal strength being refreshed. We will also make this refresh interval a configurable value so that we can change it and see how fast this can progress. Follow these steps to add the button:
Open our TelZaViBa project, you can pick up from where we left off back in Chapter 3, Mapping Signal Strength. If you are not sure, you can get the latest source code from...