// ColorScale.java
// A solution to CS 10 assignment 2, part 1, Fall 2008.
// cmc, 8/14/08

import java.awt.Color;

/**
   Represents an n-color scale as a smooth transition between
   the two terminal colors in the scale.
*/
public class ColorScale {

    private Color[] levels;

    /**
       Constructs a default (gray) scale from white to black
       with 10 levels.
    */
    public ColorScale() {
        this(Color.WHITE, Color.BLACK, 10);
    }

    /**
       Constructs a scale from first to last values specified, with
       the specified number of levels.
       @param first the first color value.
       @param last the last color value.
       @param size the number of levels - assumed to be > 0.
    */
    public ColorScale(Color first, Color last, int size) {
        levels = new Color[size];
        setLevels(first, last);
    }

    /**
       Returns a reference to the specified color level.
       @param level the color level to get - assumed to
          be in range of 0 to size()-1.
       @return color value at specified level.
    */
    public Color get(int level) { return levels[level]; }

    /**
       Returns the size of the scale.
       @return the number of levels in this scale.
    */
    public int size() { return levels.length; }

    // utility sets the levels
    private void setLevels(Color first, Color last) {
        int n = levels.length;
        levels[0] = first;
        levels[n-1] = last;

        int firstRed = first.getRed(), firstGreen = first.getGreen(),
            firstBlue = first.getBlue();
        double dRed = (double)(last.getRed() - firstRed) / (n - 1), 
            dGreen = (double)(last.getGreen() - firstGreen) / (n - 1),
            dBlue = (double)(last.getBlue() - firstBlue) / (n - 1); 

        for (int i=1; i < n-1; i++)
            levels[i] = new Color(
                (int)(firstRed + (i * dRed)),
                (int)(firstGreen + (i * dGreen)),
                (int)(firstBlue + (i * dBlue))
            );
    }
}