/*

 ============================================================================
                   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
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 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.RescaleOp;

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

/**
 * Utility class that converts a RescaleOp object into
 * an SVG filter descriptor. The SVG filter corresponding
 * to a RescaleOp is an feComponentTransfer, with a type
 * set to 'linear', the slopes equal to the RescapeOp
 * scaleFactors and the intercept equal to the RescapeOp
 * offsets.
 *
 * @author <a href="mailto:vincent.hardy@eng.sun.com">Vincent Hardy</a>
 * @version $Id: SVGRescaleOp.java,v 1.12 2003/08/08 11:39:20 vhardy Exp $
 * @see                org.apache.batik.svggen.SVGBufferedImageOp
 */
public class SVGRescaleOp extends AbstractSVGFilterConverter {

    /**
     * @param generatorContext used to build Elements
     */
    public SVGRescaleOp(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 RescaleOp)
            return toSVG((RescaleOp)filter);
        else
            return null;
    }

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

        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 RescaleOp as a BufferedImageOp,
            // the scaleFactors must be either:
            // + 1, in which case the same scale is applied to the
            //   Red, Green and Blue components,
            // + 3, in which case the scale factors apply to the
            //   Red, Green and Blue components
            // + 4, in which case the scale factors apply to the
            //   Red, Green, Blue and Alpha components
            float offsets[] = rescaleOp.getOffsets(null);
            float scaleFactors[] = rescaleOp.getScaleFactors(null);
            if(offsets.length != scaleFactors.length)
                throw new SVGGraphics2DRuntimeException(ERR_SCALE_FACTORS_AND_OFFSETS_MISMATCH);

            if(offsets.length != 1 &&
               offsets.length != 3 &&
               offsets.length != 4)
                throw new SVGGraphics2DRuntimeException(ERR_ILLEGAL_BUFFERED_IMAGE_RESCALE_OP);

            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_LINEAR_VALUE;

            if(offsets.length == 1){
                String slope = doubleString(scaleFactors[0]);
                String intercept = doubleString(offsets[0]);
                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_SLOPE_ATTRIBUTE, slope);
                feFuncG.setAttributeNS(null, SVG_SLOPE_ATTRIBUTE, slope);
                feFuncB.setAttributeNS(null, SVG_SLOPE_ATTRIBUTE, slope);
                feFuncR.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE, intercept);
                feFuncG.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE, intercept);
                feFuncB.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE, intercept);
            }
            else if(offsets.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_SLOPE_ATTRIBUTE,
                                       doubleString(scaleFactors[0]));
                feFuncG.setAttributeNS(null, SVG_SLOPE_ATTRIBUTE,
                                       doubleString(scaleFactors[1]));
                feFuncB.setAttributeNS(null, SVG_SLOPE_ATTRIBUTE,
                                       doubleString(scaleFactors[2]));
                feFuncR.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE,
                                       doubleString(offsets[0]));
                feFuncG.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE,
                                       doubleString(offsets[1]));
                feFuncB.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE,
                                       doubleString(offsets[2]));

                if(offsets.length == 4){
                    feFuncA = domFactory.createElementNS(SVG_NAMESPACE_URI,
                                                         SVG_FE_FUNC_A_TAG);
                    feFuncA.setAttributeNS(null, SVG_TYPE_ATTRIBUTE, type);
                    feFuncA.setAttributeNS(null, SVG_SLOPE_ATTRIBUTE,
                                         doubleString(scaleFactors[3]));
                    feFuncA.setAttributeNS(null, SVG_INTERCEPT_ATTRIBUTE,
                                         doubleString(offsets[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(rescaleOp, filterDesc);
        }

        return filterDesc;
    }
}
