/*
 * $RCSfile: SubbandAn.java,v $
 * $Revision: 1.1 $
 * $Date: 2005/02/11 05:02:31 $
 * $State: Exp $
 *
 * Class:                   SubbandAn
 *
 * Description:             Element for a tree structure for a descripotion
 *                          of subbands on the anslysis side.
 *
 *
 *
 * COPYRIGHT:
 *
 * This software module was originally developed by Raphaël Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 *
 * Copyright (c) 1999/2000 JJ2000 Partners.
 *
 *
 *
 */


package jj2000.j2k.wavelet.analysis;

import jj2000.j2k.wavelet.*;

/**
 * This class represents a subband in a bidirectional tree structure
 * that describes the subband decomposition for a wavelet transform,
 * specifically for the analysis side.
 *
 * <P>The element can be either a node or a leaf of the tree. If it is
 * a node then ther are 4 descendants (LL, HL, LH and HH). If it is a
 * leaf there are no descendants.
 *
 * <P>The tree is bidirectional. Each element in the tree structure
 * has a "parent", which is the subband from which the element was
 * obtained by decomposition. The only exception is the root element
 * which has no parent (i.e.it's null), for obvious reasons.
 * */
public class SubbandAn extends Subband {

    /**
     * The reference to the parent of this subband. It is null for the
     * root element. It is null by default.  */
    public SubbandAn parent = null;

    /**
     * The reference to the LL subband resulting from the
     * decomposition of this subband. It is null by default.  */
    public SubbandAn subb_LL;

    /**
     * The reference to the HL subband (horizontal high-pass)
     * resulting from the decomposition of this subband. It is null by
     * default.  */
    public SubbandAn subb_HL;

    /**
     * The reference to the LH subband (vertical high-pass) resulting
     * from the decomposition of this subband. It is null by default.
     * */
    public SubbandAn subb_LH;

    /**
     * The reference to the HH subband resulting from the
     * decomposition of this subband. It is null by default.
     */
    public SubbandAn subb_HH;

    /** The horizontal analysis filter used to decompose this
        subband. This is applicable to "node" elements only. The
        default value is null. */
    public AnWTFilter hFilter;

    /** The vertical analysis filter used to decompose this
        subband. This is applicable to "node" elements only. The
        default value is null. */
    public AnWTFilter vFilter;

    /**
     * The L2-norm of the synthesis basis waveform of this subband,
     * applicable to "leafs" only. By default it is -1 (i.e. not
     * calculated yet).
     * */
    public float l2Norm = -1.0f;

    /**
     * The contribution to the MSE or WMSE error that would result in the
     * image if there was an error of exactly one quantization step size in
     * the sample of the subband. This value is expressed relative to a
     * nominal dynamic range in the image domain of exactly 1.0. This field
     * contains valid data only after quantization 9See Quantizer).
     *
     * @see jj2000.j2k.quantization.quantizer.Quantizer
     * */
    public float stepWMSE;

    /**
     * Creates a SubbandAn element with all the default values. The
     * dimensions are (0,0) and the upper left corner is (0,0).
     *
     *
     * */
    public SubbandAn() {
    }

    /**
     * Creates the top-level node and the entire subband tree, with
     * the top-level dimensions, the number of decompositions, and the
     * decomposition tree as specified.
     *
     * <P>This constructor just calls the same constructor of the
     * super class, and then calculates the L2-norm (or energy weight)
     * of each leaf.
     *
     * <P>This constructor does not initialize the value of the magBits or
     * stepWMSE member variables. This variables are normally initialized by
     * the quantizer (see Quantizer).
     *
     * @param w The top-level width
     *
     * @param h The top-level height
     *
     * @param ulcx The horizontal coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param ulcy The vertical  coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param lvls The number of levels (or LL decompositions) in the
     * tree.
     *
     * @param hfilters The horizontal wavelet analysis filters for each
     * resolution level, starting at resolution level 0.
     *
     * @param vfilters The vertical wavelet analysis filters for each
     * resolution level, starting at resolution level 0.
     *
     * @see Subband#Subband(int,int,int,int,int,
     * WaveletFilter[],WaveletFilter[])
     *
     * @see jj2000.j2k.quantization.quantizer.Quantizer
     *
     *
     * */
    public SubbandAn(int w, int h, int ulcx, int ulcy, int lvls,
                     WaveletFilter hfilters[], WaveletFilter vfilters[]) {
        super(w,h,ulcx,ulcy,lvls,hfilters,vfilters);
        // Caculate the L2-norms
        calcL2Norms();
    }

    /**
     * Returns the parent of this subband. The parent of a subband is
     * the subband from which this one was obtained by
     * decomposition. The root element has no parent subband (null).
     *
     * @return The parent subband, or null for the root one.
     *
     *
     * */
    public Subband getParent() {
        return parent;
    }

    /**
     * Returns the LL child subband of this subband.
     *
     * @return The LL child subband, or null if there are no childs.
     *
     *
     * */
    public Subband getLL() {
        return subb_LL;
    }

    /**
     * Returns the HL (horizontal high-pass) child subband of this
     * subband.
     *
     * @return The HL child subband, or null if there are no childs.
     *
     *
     * */
    public Subband getHL() {
        return subb_HL;
    }

    /**
     * Returns the LH (vertical high-pass) child subband of this
     * subband.
     *
     * @return The LH child subband, or null if there are no childs.
     *
     *
     * */
    public Subband getLH() {
        return subb_LH;
    }

    /**
     * Returns the HH child subband of this subband.
     *
     * @return The HH child subband, or null if there are no childs.
     *
     *
     * */
    public Subband getHH() {
        return subb_HH;
    }

    /**
     * Splits the current subband in its four subbands. It changes the
     * status of this element (from a leaf to a node, and sets the
     * filters), creates the childs and initializes them. An
     * IllegalArgumentException is thrown if this subband is not a
     * leaf.
     *
     * <P>It uses the initChilds() method to initialize the childs.
     *
     * @param hfilter The horizontal wavelet filter used to decompose
     * this subband. It has to be a AnWTFilter object.
     *
     * @param vfilter The vertical wavelet filter used to decompose this
     * subband. It has to be a AnWTFilter object.
     *
     * @return  A reference to the LL leaf (subb_LL).
     *
     * @see Subband#initChilds
     *
     *
     * */
    protected Subband split(WaveletFilter hfilter, WaveletFilter vfilter) {
        // Test that this is a node
        if (isNode) {
            throw new IllegalArgumentException();
        }

        // Modify this element into a node and set the filters
        isNode = true;
        this.hFilter = (AnWTFilter) hfilter;
        this.vFilter = (AnWTFilter) vfilter;

        // Create childs
        subb_LL = new SubbandAn();
        subb_LH = new SubbandAn();
        subb_HL = new SubbandAn();
        subb_HH = new SubbandAn();

        // Assign parent
        subb_LL.parent = this;
        subb_HL.parent = this;
        subb_LH.parent = this;
        subb_HH.parent = this;

        // Initialize childs
        initChilds();

        // Return reference to LL subband
        return subb_LL;
    }

    /**
     * Calculates the basis waveform of the first leaf for which the
     * L2-norm has not been calculated yet. This method searches
     * recursively for the first leaf for which the value has not been
     * calculated yet, and then calculates the L2-norm on the return
     * path.
     *
     * <P>The wfs argument should be a size 2 array of float arrays
     * (i.e. 2D array) and it must be of length 2 (or more). When
     * returning, wfs[0] will contain the line waveform, and wfs[1]
     * will contain the column waveform.
     *
     * <P>This method can not be called on an element that ahs a
     * non-negative value in l2Norm, since that means that we are
     * done.
     *
     * @param wfs An size 2 array where the line and column waveforms
     * will be returned.
     *
     *
     * */
    private void calcBasisWaveForms(float wfs[][]) {
        if (l2Norm < 0) {
            // We are not finished with this element yet
            if (isNode) {
                // We are on a node => search on childs
                if (subb_LL.l2Norm < 0f) {
                    subb_LL.calcBasisWaveForms(wfs);
                    wfs[0] =
                        hFilter.getLPSynWaveForm(wfs[0],null);
                    wfs[1] =
                        vFilter.getLPSynWaveForm(wfs[1],null);
                }
                else if (subb_HL.l2Norm < 0f) {
                    subb_HL.calcBasisWaveForms(wfs);
                    wfs[0] =
                        hFilter.getHPSynWaveForm(wfs[0],null);
                    wfs[1] =
                        vFilter.getLPSynWaveForm(wfs[1],null);
                }
                else if (subb_LH.l2Norm < 0f) {
                    subb_LH.calcBasisWaveForms(wfs);
                    wfs[0] =
                        hFilter.getLPSynWaveForm(wfs[0],null);
                    wfs[1] =
                        vFilter.getHPSynWaveForm(wfs[1],null);
                }
                else if (subb_HH.l2Norm < 0f) {
                    subb_HH.calcBasisWaveForms(wfs);
                    wfs[0] =
                        hFilter.getHPSynWaveForm(wfs[0],null);
                    wfs[1] =
                        vFilter.getHPSynWaveForm(wfs[1],null);
                }
                else {
                    // There is an error! If all childs have
                    // non-negative l2norm, then this node should have
                    // non-negative l2norm
                    throw new Error("You have found a bug in JJ2000!");
                }
            }
            else {
                // This is a leaf, just use diracs (null is
                // equivalent to dirac)
                wfs[0] = new float[1];
                wfs[0][0] = 1.0f;
                wfs[1] = new float[1];
                wfs[1][0] = 1.0f;
            }

        }
        else {
            // This is an error! The calcBasisWaveForms() method is
            // never called on an element with non-negative l2norm
            throw new Error("You have found a bug in JJ2000!");
        }
    }

    /**
     * Assigns the given L2-norm to the first leaf that does not have
     * an L2-norm value yet (i.e. l2norm is negative). The search is
     * done recursively and in the same order as that of the
     * calcBasisWaveForms() method, so that this method is used to
     * assigne the l2norm of the previously computed waveforms.
     *
     * <P>This method can not be called on an element that ahs a
     * non-negative value in l2Norm, since that means that we are
     * done.
     *
     * @param l2n The L2-norm to assign.
     *
     *
     * */
    private void assignL2Norm(float l2n) {
        if (l2Norm < 0) {
            // We are not finished with this element yet
            if (isNode) {
                // We are on a node => search on childs
                if (subb_LL.l2Norm < 0f) {
                    subb_LL.assignL2Norm(l2n);
                }
                else if (subb_HL.l2Norm < 0f) {
                    subb_HL.assignL2Norm(l2n);
                }
                else if (subb_LH.l2Norm < 0f) {
                    subb_LH.assignL2Norm(l2n);
                }
                else if (subb_HH.l2Norm < 0f) {
                    subb_HH.assignL2Norm(l2n);
                    // If child now is done, we are done
                    if (subb_HH.l2Norm >= 0f) {
                        l2Norm = 0f; // We are on a node, any non-neg value OK
                    }
                }
                else {
                    // There is an error! If all childs have
                    // non-negative l2norm, then this node should have
                    // non-negative l2norm
                    throw new Error("You have found a bug in JJ2000!");
                }
            }
            else {
                // This is a leaf, assign the L2-norm
                l2Norm = l2n;
            }

        }
        else {
            // This is an error! The assignL2Norm() method is
            // never called on an element with non-negative l2norm
            throw new Error("You have found a bug in JJ2000!");
        }
    }


    /**
     * Calculates the L2-norm of the sythesis waveforms of every leaf
     * in the tree. This method should only be called on the root
     * element.
     *
     *
     * */
    private void calcL2Norms() {
        int i;
        float wfs[][] = new float[2][];
        double acc;
        float l2n;

        // While we are not done on the root element, compute basis
        // functions and assign L2-norm
        while (l2Norm < 0f) {
            calcBasisWaveForms(wfs);
            // Compute line L2-norm, which is the product of the line
            // and column L2-norms
            acc = 0.0;
            for (i=wfs[0].length-1; i>=0; i--) {
                acc += wfs[0][i]*wfs[0][i];
            }
            l2n = (float) Math.sqrt(acc);
            // Compute column L2-norm
            acc = 0.0;
            for (i=wfs[1].length-1; i>=0; i--) {
                acc += wfs[1][i]*wfs[1][i];
            }
            l2n *= (float) Math.sqrt(acc);
            // Release waveforms
            wfs[0] = null;
            wfs[1] = null;
            // Assign the value
            assignL2Norm(l2n);
        }
    }

    /**
     * This function returns the horizontal wavelet filter relevant to this
     * subband
     *
     * @return The horizontal wavelet filter
     *
     *
     */
    public WaveletFilter getHorWFilter(){
        return hFilter;
    }

    /**
     * This function returns the vertical wavelet filter relevant to this
     * subband
     *
     * @return The vertical wavelet filter
     *
     *
     */
    public WaveletFilter getVerWFilter(){
        return hFilter;
    }
}