/*

 ============================================================================
                   The Apache Software License, Version 1.1
 ============================================================================

 Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.

 Redistribution and use in source and binary forms, with or without modifica-
 tion, are permitted provided that the following conditions are met:

 1. Redistributions of  source code must  retain the above copyright  notice,
    this list of conditions and the following disclaimer.

 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

 3. The end-user documentation included with the redistribution, if any, must
    include  the following  acknowledgment:  "This product includes  software
    developed  by the  Apache Software Foundation  (http://www.apache.org/)."
    Alternately, this  acknowledgment may  appear in the software itself,  if
    and wherever such third-party acknowledgments normally appear.

 4. The names "Batik" and  "Apache Software Foundation" must  not  be
    used to  endorse or promote  products derived from  this software without
    prior written permission. For written permission, please contact
    apache@apache.org.

 5. Products  derived from this software may not  be called "Apache", nor may
    "Apache" appear  in their name,  without prior written permission  of the
    Apache Software Foundation.

 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
 APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
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 This software  consists of voluntary contributions made  by many individuals
 on  behalf of the Apache Software  Foundation. For more  information on the
 Apache Software Foundation, please see <http://www.apache.org/>.

*/

package org.apache.batik.svggen;

import java.awt.Rectangle;
import java.awt.image.BufferedImageOp;
import java.awt.image.ByteLookupTable;
import java.awt.image.LookupOp;
import java.awt.image.LookupTable;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * Utility class that converts a LookupOp object into
 * an SVG filter descriptor. The SVG filter corresponding
 * to a LookupOp is an feComponentTransfer, with a type
 * set to 'table', the tableValues set to the content
 * of the lookup table.
 *
 * @author <a href="mailto:vincent.hardy@eng.sun.com">Vincent Hardy</a>
 * @version $Id: SVGLookupOp.java,v 1.15 2003/08/08 11:39:20 vhardy Exp $
 * @see                org.apache.batik.svggen.SVGBufferedImageOp
 */
public class SVGLookupOp extends AbstractSVGFilterConverter {
    /**
     * Gamma for linear to sRGB convertion
     */
    private static final double GAMMA = 1./2.4;

    /**
     * Lookup table for linear to sRGB value
     * forward and backward mapping
     */
    private static final int linearToSRGBLut[] = new int[256];
    private static final int sRGBToLinear[] = new int[256];

    static {
        for(int i=0; i<256; i++) {
            // linear to sRGB
            float value = i/255f;
            if (value <= 0.0031308) {
                value *= 12.92f;
            } else {
                value = 1.055f * ((float) Math.pow(value, GAMMA)) - 0.055f;
            }
            linearToSRGBLut[i] = Math.round(value*255);

            // sRGB to linear
            value = i/255f;
            if(value <= 0.04045){
                value /= 12.92f;
            } else {
                value = (float)Math.pow((value + 0.055f)/1.055f, 1/GAMMA);
            }

            sRGBToLinear[i] = Math.round(value*255);
        }
    }

    /**
     * @param generatorContext used to build Elements
     */
    public SVGLookupOp(SVGGeneratorContext generatorContext) {
        super(generatorContext);
    }

    /**
     * Converts a Java 2D API BufferedImageOp into
     * a set of attribute/value pairs and related definitions
     *
     * @param op BufferedImageOp filter to be converted
     * @param filterRect Rectangle, in device space, that defines the area
     *        to which filtering applies. May be null, meaning that the
     *        area is undefined.
     * @return descriptor of the attributes required to represent
     *         the input filter
     * @see org.apache.batik.svggen.SVGFilterDescriptor
     */
    public SVGFilterDescriptor toSVG(BufferedImageOp filter,
                                     Rectangle filterRect) {
        if (filter instanceof LookupOp)
            return toSVG((LookupOp)filter);
        else
            return null;
    }

    /**
     * @param lookupOp the LookupOp to be converted
     * @return a description of the SVG filter corresponding to
     *         lookupOp. The definition of the feComponentTransfer
     *         filter in put in feComponentTransferDefSet
     */
    public SVGFilterDescriptor toSVG(LookupOp lookupOp) {
        // Reuse definition if lookupOp has already been converted
        SVGFilterDescriptor filterDesc =
            (SVGFilterDescriptor)descMap.get(lookupOp);

        Document domFactory = generatorContext.domFactory;

        if (filterDesc == null) {
            //
            // First time filter is converted: create its corresponding
            // SVG filter
            //
            Element filterDef = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                           SVG_FILTER_TAG);
            Element feComponentTransferDef =
                domFactory.createElementNS(SVG_NAMESPACE_URI,
                                           SVG_FE_COMPONENT_TRANSFER_TAG);

            // Append transfer function for each component, setting
            // the attributes corresponding to the scale and offset.
            // Because we are using a LookupOp as a BufferedImageOp,
            // the number of lookup table must be:
            // + 1, in which case the same lookup is applied to the
            //   Red, Green and Blue components,
            // + 3, in which case the lookup tables apply to the
            //   Red, Green and Blue components
            // + 4, in which case the lookup tables apply to the
            //   Red, Green, Blue and Alpha components
            String lookupTables[] = convertLookupTables(lookupOp);

            Element feFuncR = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                         SVG_FE_FUNC_R_TAG);
            Element feFuncG = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                         SVG_FE_FUNC_G_TAG);
            Element feFuncB = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                         SVG_FE_FUNC_B_TAG);
            Element feFuncA = null;
            String type = SVG_TABLE_VALUE;

            if(lookupTables.length == 1){
                feFuncR.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncG.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncB.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncR.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[0]);
                feFuncG.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[0]);
                feFuncB.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[0]);
            }
            else if(lookupTables.length >= 3){
                feFuncR.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncG.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncB.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                feFuncR.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[0]);
                feFuncG.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[1]);
                feFuncB.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                       lookupTables[2]);

                if(lookupTables.length == 4){
                    feFuncA = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                         SVG_FE_FUNC_A_TAG);
                    feFuncA.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                    feFuncA.setAttributeNS(null, SVG_TABLE_VALUES_ATTRIBUTE,
                                           lookupTables[3]);
                }
            }

            feComponentTransferDef.appendChild(feFuncR);
            feComponentTransferDef.appendChild(feFuncG);
            feComponentTransferDef.appendChild(feFuncB);
            if(feFuncA != null)
                feComponentTransferDef.appendChild(feFuncA);

            filterDef.appendChild(feComponentTransferDef);

            filterDef.
                setAttributeNS(null, ATTR_ID,
                               generatorContext.idGenerator.
                               generateID(ID_PREFIX_FE_COMPONENT_TRANSFER));
            //
            // Create a filter descriptor
            //

            // Process filter attribute
            StringBuffer filterAttrBuf = new StringBuffer(URL_PREFIX);
            filterAttrBuf.append(SIGN_POUND);
            filterAttrBuf.append(filterDef.getAttributeNS(null, ATTR_ID));
            filterAttrBuf.append(URL_SUFFIX);

            filterDesc = new SVGFilterDescriptor(filterAttrBuf.toString(),
                                                 filterDef);

            defSet.add(filterDef);
            descMap.put(lookupOp, filterDesc);
        }

        return filterDesc;
    }

    /**
     * Converts the filter's LookupTable into an array of corresponding SVG
     * table strings
     */
    private String[] convertLookupTables(LookupOp lookupOp){
        LookupTable lookupTable = lookupOp.getTable();
        int nComponents = lookupTable.getNumComponents();

        if((nComponents != 1) && (nComponents != 3) && (nComponents != 4))
            throw new SVGGraphics2DRuntimeException(ERR_ILLEGAL_BUFFERED_IMAGE_LOOKUP_OP);

        StringBuffer lookupTableBuf[] = new StringBuffer[nComponents];
        for(int i=0; i<nComponents; i++)
            lookupTableBuf[i] = new StringBuffer();

        if(!(lookupTable instanceof ByteLookupTable)){
            int src[] = new int[nComponents];
            int dest[] = new int[nComponents];
            int offset = lookupTable.getOffset();

            // Offsets are used for constrained sources. Therefore,
            // the lookup values should never be used under offset.
            // There is no SVG equivalent for this behavior.
            // These values are mapped to identity.
            for(int i=0; i<offset; i++){
                // Fill in string buffers
                for(int j=0; j<nComponents; j++){
                    // lookupTableBuf[j].append(Integer.toString(i));
                    lookupTableBuf[j].append(doubleString(i/255.));
                    lookupTableBuf[j].append(SPACE);
                }
            }

            for(int i=offset; i<=255; i++){
                // Fill in source array
                for(int j=0; j<nComponents; j++) src[j] = i;

                // Get destination values
                lookupTable.lookupPixel(src, dest);

                // Fill in string buffers
                for(int j=0; j<nComponents; j++){
                    lookupTableBuf[j].append(doubleString(dest[j]/255.));
                    // lookupTableBuf[j].append(Integer.toString(dest[j]));
                    lookupTableBuf[j].append(SPACE);
                }
            }
        }
        else{
            byte src[] = new byte[nComponents];
            byte dest[] = new byte[nComponents];

            int offset = lookupTable.getOffset();

            // Offsets are used for constrained sources. Therefore,
            // the lookup values should never be used under offset.
            // There is no SVG equivalent for this behavior.
            // These values are mapped to identity.
            for(int i=0; i<offset; i++){
                // Fill in string buffers
                for(int j=0; j<nComponents; j++){
                    // lookupTableBuf[j].append(Integer.toString(i));
                    lookupTableBuf[j].append(doubleString(i/255.));
                    lookupTableBuf[j].append(SPACE);
                }
            }
            for(int i=0; i<=255; i++){
                // Fill in source array
                for(int j=0; j<nComponents; j++) {
                    src[j] = (byte)(0xff & i);
                }

                // Get destination values
                ((ByteLookupTable)lookupTable).lookupPixel(src, dest);

                // Fill in string buffers
                for(int j=0; j<nComponents; j++){
                    lookupTableBuf[j].append(doubleString((0xff & dest[j])/255.));
                    lookupTableBuf[j].append(SPACE);
                }
            }
        }

        String lookupTables[] = new String[nComponents];
        for(int i=0; i<nComponents; i++)
            lookupTables[i] = lookupTableBuf[i].toString().trim();

        /*for(int i=0; i<lookupTables.length; i++){
            System.out.println(lookupTables[i]);
            }*/

        return lookupTables;
    }
}
