TiffRational.java

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package loci.formats.tiff;

/**
 * A rational number (numerator over denominator).
 *
 * @author Curtis Rueden ctrueden at wisc.edu
 */
public class TiffRational extends Number implements Comparable<TiffRational> {

  // -- Fields --

  /** Components of the rational's fractional representation. */
  protected long numer, denom;

  // -- Constructor --

  /** Constructs a rational number. */
  public TiffRational(long numer, long denom) {
    this.numer = numer;
    this.denom = denom;
  }

  // -- TiffRational API methods --

  /** Gets this number's numerator. */
  public long getNumerator() { return numer; }

  /** Gets this number's denominator. */
  public long getDenominator() { return denom; }

  /** Reduces this rational's fraction to lowest terms. */
  public void reduce() {
    long sqrt1 = (long) Math.sqrt(numer);
    long sqrt2 = (long) Math.sqrt(denom);
    long gcdMax = sqrt1 < sqrt2 ? sqrt1 : sqrt2;
    // search for greatest common divisor
    for (long i=gcdMax; i>=2; i--) {
      if (numer % i == 0 && denom % i == 0) {
        numer /= i;
        denom /= i;
        reduce();
        break;
      }
    }
  }

  // -- Number API methods --

  /** Returns the value of the specified number as a byte. */
  @Override
  public byte byteValue() { return (byte) longValue(); }

  /** Returns the value of the specified number as a double. */
  @Override
  public double doubleValue() {
    return denom == 0 ? Double.MAX_VALUE : ((double) numer / (double) denom);
  }

  /** Returns the value of the specified number as a float. */
  @Override
  public float floatValue() { return (float) doubleValue(); }

  /** Returns the value of the specified number as an int. */
  @Override
  public int intValue() { return (int) longValue(); }

  /** Returns the value of the specified number as a long. */
  @Override
  public long longValue() {
    return denom == 0 ? Long.MAX_VALUE : (numer / denom);
  }

  /** Returns the value of the specified number as a short. */
  @Override
  public short shortValue() { return (short) longValue(); }

  // -- Object API methods --

  /** Indicates whether some other object is "equal to" this one. */
  @Override
  public boolean equals(Object o) {
    return o != null && o instanceof TiffRational &&
      compareTo((TiffRational) o) == 0;
  }

  /** Reasonable hash value for use with hashtables. */
  @Override
  public int hashCode() { return (int) (numer - denom); }

  /** Returns a string representation of the object. */
  @Override
  public String toString() { return numer + "/" + denom; }

  // -- Comparable API methods --

  /**
   * Compares this object with the specified object for order.
   * Returns a negative integer, zero, or a positive integer as this object
   * is less than, equal to, or greater than the specified object.
   */
  @Override
  public int compareTo(TiffRational q) {
    long diff = (numer * q.denom - q.numer * denom);
    if (diff > Integer.MAX_VALUE) diff = Integer.MAX_VALUE;
    else if (diff < Integer.MIN_VALUE) diff = Integer.MIN_VALUE;
    return (int) diff;
  }

}