X-Git-Url: http://gitweb.fperrin.net/?p=GpsPrune.git;a=blobdiff_plain;f=src%2Ftim%2Fprune%2Fjpeg%2Fdrew%2FRational.java;fp=src%2Ftim%2Fprune%2Fjpeg%2Fdrew%2FRational.java;h=8395898266677c16593604c8a04a0826db490225;hp=0000000000000000000000000000000000000000;hb=ce6f2161b8596f7018d6a76bff79bc9e571f35fd;hpb=2d8cb72e84d5cc1089ce77baf1e34ea3ea2f8465

diff --git a/src/tim/prune/jpeg/drew/Rational.java b/src/tim/prune/jpeg/drew/Rational.java
new file mode 100644
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+++ b/src/tim/prune/jpeg/drew/Rational.java
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+package tim.prune.jpeg.drew;
+
+/**
+ * Immutable class for holding a rational number without loss of precision.
+ * Based on Drew Noakes' Metadata extractor at https://drewnoakes.com
+ */
+public class Rational
+{
+	/** Holds the numerator */
+	private final long _numerator;
+
+	/** Holds the denominator */
+	private final long _denominator;
+
+	/**
+	 * Creates a new (immutable) instance of Rational.
+	 */
+	public Rational(long numerator, long denominator)
+	{
+		_numerator = numerator;
+		_denominator = denominator;
+	}
+
+	/**
+	 * @return the value of the specified number as a <code>double</code>.
+	 * This may involve rounding.
+	 */
+	public double doubleValue()
+	{
+		if (_denominator == 0L) return 0.0;
+		return (double)_numerator / (double)_denominator;
+	}
+
+	/**
+	 * Returns the value of the specified number as an <code>int</code>.
+	 */
+	public final int intValue()
+	{
+		return (int) longValue();
+	}
+
+	/**
+	 * Returns the value of the specified number as a <code>long</code>.
+	 * This may involve rounding or truncation.
+	 * If the denominator is 0, returns 0 to avoid dividing by 0.
+	 */
+	public final long longValue()
+	{
+		if (_denominator == 0L) return 0L;
+		return _numerator / _denominator;
+	}
+
+	/** Returns the denominator */
+	public final long getDenominator()
+	{
+		return _denominator;
+	}
+
+	/** Returns the numerator */
+	public final long getNumerator()
+	{
+		return _numerator;
+	}
+
+	/**
+	 * @return the value of the specified number as a positive <code>double</code>.
+	 * Prevents interpretation of 32 bit numbers as negative, and forces a positive answer.
+	 * Needed?
+	 */
+	public double convertToPositiveValue()
+	{
+		if (_denominator == 0L) return 0.0;
+		double numeratorDbl = _numerator;
+		double denomDbl = _denominator;
+		if (_numerator >= 0L) {
+			// Numerator is positive (but maybe denominator isn't?)
+			return numeratorDbl / denomDbl;
+		}
+		// Add 2^32 to negative doubles to make them positive
+		final double correction = Math.pow(2.0, 32);
+		numeratorDbl += correction;
+		if (_denominator < 0L) {
+			denomDbl += correction;
+		}
+		return numeratorDbl / denomDbl;
+	}
+
+	/**
+	 * Returns a string representation of the object of form <code>numerator/denominator</code>.
+	 */
+	@Override
+	public String toString()
+	{
+		return "" + _numerator + "/" + _denominator;
+	}
+
+	/**
+	 * Compares two {@link Rational} instances, returning true if they are mathematically
+	 * equivalent.
+	 *
+	 * @param obj the {@link Rational} to compare this instance to.
+	 * @return true if instances are mathematically equivalent, otherwise false.  Will also
+	 *         give false if <code>obj</code> is not an instance of {@link Rational}.
+	 */
+	@Override
+	public boolean equals( Object obj)
+	{
+		if (obj==null || !(obj instanceof Rational))
+			return false;
+		Rational that = (Rational) obj;
+		return this.doubleValue() == that.doubleValue();
+	}
+}