LineMetrics
Holds line metrics data
For the meaning of the members see https://docs.oracle.com/javase/tutorial/2d/text/fontconcepts.html
Ascent is the distance from the baseline to the typical highest point of the letter (ascender line). Descent is the distance from the baseline to the typical lowest point of the letter (descender line). Leading is the gap between lines, i.e. distance from the descender line to the next line's ascender line.
trait Serializable
trait Product
trait Equals
class Object
trait Matchable
class Any