org.apache.fop.pdf.PDFFilter Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id: PDFFilter.java 1610839 2014-07-15 20:25:58Z vhennebert $ */
package org.apache.fop.pdf;
import java.io.IOException;
import java.io.OutputStream;
/**
* PDF Filter class.
* This class represents a PDF filter object.
* Filter implementations should extend this class.
*
* This work was authored by Eric Schaeffer and 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;
/**
* 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 PDFObject 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;
}