Negative Font Util 2

FontOffsetUtil.java

public class FontOffsetUtil {

    private static final char MINUS_START = '\uF800';
    private static final char PLUS_START = '\uF820';

    private static final char MINUS_POW_START = '\uF808';
    private static final char PLUS_POW_START = '\uF828';

    public static String getOffset(int offset) {
        //If no offset, return empty string
        if(offset == 0) return "";

        int abs = Math.abs(offset);

        if(abs <= 8) {
            //If magnitude <8, return the character directly
            return ""+(char)((offset < 0 ? MINUS_START : PLUS_START) + abs);
        } else {
            //If magnitude >8, use closest power of two and recursively call getOffset

            //Find power of two - 3
            double logBaseTwo = Math.log(abs)/Math.log(2) - 3;

            //Find offset from MINUS_POW_START or PLUS_POW_START of character to be used
            int index = (int)Math.round(logBaseTwo);

            //Find the amount offset has changed by given this power of two
            int delta = (int)Math.round(Math.copySign(Math.pow(2, index+3), offset));
            char c = (char)((offset < 0 ? MINUS_POW_START : PLUS_POW_START) + index);

            //Offset should now be closer to 0, call getOffset again
            return c + getOffset(offset - delta);
        }
    }
}