package bmpviewer.bmp;

/**
 * color(RGB 24-bit) counter.
 * <p>
 *   generates color table.<br>
 *   converts color to index.<br>
 * <p>
 * @author      Hiroyuki Murata
 * @since       JDK1.1
 */
public class RGBCounter {
    private int[][][] tree;
    private int[] pix,tbl;
    private int lim,count, rrggbb,rr,gg,bb;

    /**
     * constructor
     * <p>
     * @param pix  array of pixels.
     * @param lim  counter limit.
     */
    public RGBCounter(int[] pix, int lim) {
        this.pix = pix;
        this.lim = lim;
        tree = new int[256][][];
        tbl = new int[lim+1];
    }

    //------------------------------------------------------
    /**
     * count number of colors
     */
    public int count() {
        for (int i=0; i<pix.length; i++) {
            splitRGB(pix[i]);

            if (tree[rr] == null) {
                if (overCount()) break;
                tree[rr]         = new int[256][];
                tree[rr][gg]     = new int[256];
                addRGB(true);
            } else if (tree[rr][gg] == null) {
                if (overCount()) break;
                tree[rr][gg]     = new int[256];
                addRGB(true);
            } else if (tree[rr][gg][bb] < 0) {
                if (overCount()) break;
                addRGB(false);
            }
        }
        return count;
    }

    /**
     * check count over
     */
    private boolean overCount() {
        boolean over = count >= lim;
        if (over)
            count = -1;
        return over;
    }

    /**
     * RGB -> R,G,B
     */
    private void splitRGB(int col) {
        rrggbb = col & 0xffffff;
        rr = (rrggbb >> 16)       ;
        gg = (rrggbb >>  8) & 0xff;
        bb =  rrggbb        & 0xff;
    }

    /**
     * register new color
     */
    private void addRGB(boolean init) {
        if (init) {
            for (int i=0; i<256; i++)
                tree[rr][gg][i] = -1;
        }
        tree[rr][gg][bb] = count;
        tbl[count] = rrggbb;
        count++;
    }

    //------------------------------------------------------
    /**
     * get color table (RGBQuad)
     */
    public int[] getTable() {
        if (count > lim) return null;
        else             return tbl;
    }

    /**
     * color -> index
     */
    public int getIndex(int col) {
        splitRGB(col);
        return tree[rr][gg][bb];
    }
}