I've been back working on my driver tools app this evening and I've been messing about with the graph styling. So far I've had a look through the XYPlot class to see what's available for styling the graphs and I've added '€' as a prefix to the range increments and I've also corrected how they were being displayed so that now they display to the correct number of decimal places. Other changes to the way in which the fuel price over time graph include setting the domain boundary to a fixed minimum of 0 and setting the maximum range boundary to 50 which can grow should the data exceed this boundary.
Finally I've added a couple of new methods to the stats display activity class for pulling data the from the database, calculating the data required and then adding them to data structures that can be used to plot graphs. I've changed where the function is called from within the activity to the onResume() method, so that the graphs will update every time the activity is popped from the activity stack. This means that the graphs will always update when the focus returns to the stats GUI because the only way of invoking a change to the way in which stats is through other activities which will push the stats activity to the activity stack.
The next steps involve calculating the distances between each transaction which should be easy enough, as it's a simple subtraction. The distance between transactions is going to have to be calculated from the first transaction onwards for now, until when picking your car you can initially set the odometer.
The fuel economy is going to be more difficult to calculate, although the actual formula is easy, the MPG is going to result in issues due to the fact that if someone decides to refill their tank when it's not empty they will get a very low fuel economy rating. I'll implement it anyway and think of a solution later as the solution will probably involve adding a check at the point where a user enters the transaction details.
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