DefaultScore.java

package com.mebigfatguy.polycasso;

/**
 * a default implementation of a score for the error in a image against a target image this score maintains a grid of scores representing scores in sections of
 * the image, and then rolls up these scores to an overall score.
 */
public class DefaultScore implements Score {

    private static final long serialVersionUID = 2603006530810631094L;
    static final int NUM_DIVISIONS = 8;

    /**
     * a worst case score
     */
    public static final DefaultScore MAX_SCORE = new DefaultScore(Long.MAX_VALUE);

    long gridScores[][] = new long[NUM_DIVISIONS][NUM_DIVISIONS];
    long overallScore;

    /**
     * constructs an empty score
     */
    public DefaultScore() {
        overallScore = 0;
    }

    /**
     * constructs a score with the specified delta, spreads the score across all grids
     *
     * @param delta
     *            the delta score
     */
    public DefaultScore(long delta) {
        overallScore = delta;

        long divider = NUM_DIVISIONS * NUM_DIVISIONS;
        long gridScore = overallScore / divider;

        for (int y = 0; y < NUM_DIVISIONS; y++) {
            for (int x = 0; x < NUM_DIVISIONS; x++) {
                gridScores[x][y] = gridScore;
            }
        }
    }

    /**
     * returns the sum of the square of pixel errors
     * 
     * @return the delta between a generate image and the target
     */
    @Override
    public long getDelta() {
        return overallScore;
    }

    /**
     * compares this score to another
     *
     * @param o
     *            the score to compare to
     * @return whether the two scores have the same delta
     */
    @Override
    public boolean equals(Object o) {
        if (!(o instanceof DefaultScore)) {
            return false;
        }

        return getDelta() == ((DefaultScore) o).getDelta();
    }

    /**
     * clones this object
     *
     * @return a clone
     */
    @Override
    public DefaultScore clone() {
        DefaultScore clonedScore;

        try {
            clonedScore = (DefaultScore) super.clone();
        } catch (CloneNotSupportedException cnse) {
            clonedScore = new DefaultScore();
            clonedScore.overallScore = overallScore;
        }

        clonedScore.gridScores = new long[NUM_DIVISIONS][NUM_DIVISIONS];
        for (int i = 0; i < NUM_DIVISIONS; i++) {
            System.arraycopy(gridScores[i], 0, clonedScore.gridScores[i], 0, NUM_DIVISIONS);
        }

        return clonedScore;
    }

    /**
     * generates a hash code for this score
     *
     * @return the hash code of this score
     */
    @Override
    public int hashCode() {
        return (int) overallScore;
    }

    /**
     * returns a string representation of the score
     *
     * @return the score as a string
     */
    @Override
    public String toString() {
        return String.valueOf(overallScore);
    }
}