So, you can look at BatteryMeterDrawable_Base.java for that. And, pay attention to the green text. it explains what is there.
The last, BatteryMeterDrawable.smali.. You'll see something almost similar. Take a look a keywords in java files, and then try to solve in your smali's .
Sometimes, it needs to decompile other files as well. I'm just trying to help as much as I can