fop/src/java/org/apache/fop/pdf/PDFFilter.java

/*
 * $Id: PDFFilter.java,v 1.6 2003/03/07 08:25:46 jeremias Exp $
 * ============================================================================
 *                    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 "FOP" 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,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLU-
 * DING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ============================================================================
 * 
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Apache Software Foundation and was originally created by
 * James Tauber <jtauber@jtauber.com>. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */ 
package org.apache.fop.pdf;

import java.io.OutputStream; 
import java.io.IOException;

/**
 * PDF Filter class.
 * This represents a PDF filter object.
 * Filter implementations should extend this class.
 *
 * @author Eric SCHAEFFER, Kelly A. Campbell
 */
public abstract class PDFFilter {
    /*
     * These are no longer needed, but are here as a reminder about what
     * filters pdf supports.
     * public static final int ASCII_HEX_DECODE = 1;
     * public static final int ASCII_85_DECODE = 2;
     * public static final int LZW_DECODE = 3;
     * public static final int RUN_LENGTH_DECODE = 4;
     * public static final int CCITT_FAX_DECODE = 5;
     * public static final int DCT_DECODE = 6;
     * public static final int FLATE_DECODE = 7;
     */

    /**
     * Marker to know if this filter has already been applied to the data
     */
    private boolean applied = false;

    /**
     * Check if this filter has been applied.
     *
     * @return true if this filter has been applied
     */
    public boolean isApplied() {
        return applied;
    }

    /**
     * Set the applied attribute to the given value. This attribute is
     * used to determine if this filter is just a placeholder for the
     * decodeparms and dictionary entries, or if the filter needs to
     * actually encode the data. For example if the raw data is copied
     * out of an image file in it's compressed format, then this
     * should be set to true and the filter options should be set to
     * those which the raw data was encoded with.
     *
     * @param b set the applied value to this
     */
    public void setApplied(boolean b) {
        applied = b;
    }

    /**
     * return a PDF string representation of the filter, e.g. /FlateDecode
     *
     * @return the filter PDF name
     */
    public abstract String getName();

    /**
     * Returns true if the filter is an ASCII filter that isn't necessary
     * when encryption is active.
     * @return boolean True if this filter is an ASCII filter
     */
    public boolean isASCIIFilter() {
        return false;
    }

    /**
     * return a parameter dictionary for this filter, or null
     *
     * @return the decode params for the filter
     */
    public abstract String getDecodeParms();

    /**
     * Applies a filter to an OutputStream.
     * @param out contents to be filtered
     * @return OutputStream filtered contents
     * @throws IOException In case of an I/O problem
     */
    public abstract OutputStream applyFilter(OutputStream out) throws IOException;

}