/*
* 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.
*/
/* $Id$ */
package org.apache.xmlgraphics.ps.dsc.tools;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.xmlgraphics.ps.DSCConstants;
import org.apache.xmlgraphics.ps.PSGenerator;
import org.apache.xmlgraphics.ps.dsc.DSCException;
import org.apache.xmlgraphics.ps.dsc.DSCFilter;
import org.apache.xmlgraphics.ps.dsc.DSCParser;
import org.apache.xmlgraphics.ps.dsc.DSCParserConstants;
import org.apache.xmlgraphics.ps.dsc.DefaultNestedDocumentHandler;
import org.apache.xmlgraphics.ps.dsc.events.DSCComment;
import org.apache.xmlgraphics.ps.dsc.events.DSCCommentPage;
import org.apache.xmlgraphics.ps.dsc.events.DSCCommentPages;
import org.apache.xmlgraphics.ps.dsc.events.DSCEvent;
import org.apache.xmlgraphics.ps.dsc.events.DSCHeaderComment;
/**
* This class can extract a certain range of pages from a DSC-compliant PostScript file.
*/
public class PageExtractor implements DSCParserConstants {
/**
* Parses a DSC-compliant file and pipes the content through to the OutputStream omitting
* all pages not within the range.
* @param in the InputStream to parse from
* @param out the OutputStream to write the modified file to
* @param from the starting page (1-based)
* @param to the last page (inclusive, 1-based)
* @throws IOException In case of an I/O error
* @throws DSCException In case of a violation of the DSC spec
*/
public static void extractPages(InputStream in, OutputStream out, int from, int to)
throws IOException, DSCException {
if (from <= 0) {
throw new IllegalArgumentException("'from' page number must be 1 or higher");
}
if (to < from) {
throw new IllegalArgumentException(
"'to' page number must be equal or larger than the 'from' page number");
}
DSCParser parser = new DSCParser(in);
PSGenerator gen = new PSGenerator(out);
parser.setNestedDocumentHandler(new DefaultNestedDocumentHandler(gen));
int pageCount = 0;
//Skip DSC header
DSCHeaderComment header = DSCTools.checkAndSkipDSC30Header(parser);
header.generate(gen);
//Set number of pages
DSCCommentPages pages = new DSCCommentPages(to - from + 1);
pages.generate(gen);
parser.setFilter(new DSCFilter() {
public boolean accept(DSCEvent event) {
if (event.isDSCComment()) {
//Filter %%Pages which we add manually above
return !event.asDSCComment().getName().equals(DSCConstants.PAGES);
} else {
return true;
}
}
});
//Skip the prolog and to the first page
DSCComment pageOrTrailer = parser.nextDSCComment(DSCConstants.PAGE, gen);
if (pageOrTrailer == null) {
throw new DSCException("Page expected, but none found");
}
parser.setFilter(null); //Remove filter
//Process individual pages (and skip as necessary)
while (true) {
DSCCommentPage page = (DSCCommentPage)pageOrTrailer;
boolean validPage = (page.getPagePosition() >= from && page.getPagePosition() <= to);
if (validPage) {
page.setPagePosition(page.getPagePosition() - from + 1);
page.generate(gen);
pageCount++;
}
pageOrTrailer = DSCTools.nextPageOrTrailer(parser, (validPage ? gen : null));
if (pageOrTrailer == null) {
throw new DSCException("File is not DSC-compliant: Unexpected end of file");
} else if (!DSCConstants.PAGE.equals(pageOrTrailer.getName())) {
pageOrTrailer.generate(gen);
break;
}
}
//Write the rest
while (parser.hasNext()) {
DSCEvent event = parser.nextEvent();
event.generate(gen);
}
}
}