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Package containing tasks implemented using sambox.
/*
* Created on 29 gen 2016
* Copyright 2015 by Andrea Vacondio ([email protected]).
* This file is part of Sejda.
*
* Sejda is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Sejda is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with Sejda. If not, see .
*/
package org.sejda.impl.sambox.component.optimization;
import java.util.Objects;
import java.util.Set;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.sejda.impl.sambox.component.ReadOnlyFilteredCOSStream;
import org.sejda.sambox.cos.COSDictionary;
import org.sejda.sambox.cos.COSName;
import org.sejda.sambox.cos.COSStream;
import org.sejda.sambox.pdmodel.PDDocument;
import org.sejda.sambox.pdmodel.PDPage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Component that walks through the page tree, finds resource dictionaries and removes any image xobject (type xobject, subtype image) that is not wrapped by a
* {@link ReadOnlyFilteredCOSStream} and any font that is not wrapped by a {@link InUseFontDictionary}. This is the step performed after pages content stream have been already
* parsed, all used image wrapped by a {@link ReadOnlyFilteredCOSStream} and all used fonts wrapped by a {@link InUseFontDictionary} and placed back to the resource dictionary.
* This is done in two steps because dictionaries can be shared/inherited by pages so we can't take a single page, identify used images and remove the remaining because that same
* resource dictionary can be used by other pages.
*
* @author Andrea Vacondio
*
*/
public class ResourceDictionaryCleaner implements Consumer {
private static final Logger LOG = LoggerFactory.getLogger(ResourceDictionaryCleaner.class);
@Override
public void accept(PDDocument p) {
LOG.debug("Cleaning resource dictionaries from unused resources");
clean(p.getPages().streamNodes());
}
public void clean(PDPage page) {
clean(Stream.of(page.getCOSObject()));
}
private void clean(Stream nodes) {
// clean all the resource dictionaries found at any level in the page tree
Set resources = nodes.map(d -> d.getDictionaryObject(COSName.RESOURCES, COSDictionary.class))
.filter(Objects::nonNull).collect(Collectors.toSet());
cleanResources(resources);
// clean all the resource dictionaries found in any xobject form
Set formsResources = resources.stream()
.map(d -> d.getDictionaryObject(COSName.XOBJECT, COSDictionary.class)).filter(Objects::nonNull)
.flatMap(d -> d.getValues().stream()).filter(d -> d.getCOSObject() instanceof COSDictionary)
.map(d -> (COSDictionary) d.getCOSObject())
.filter(d -> COSName.FORM.equals(d.getCOSName(COSName.SUBTYPE)))
.map(d -> d.getDictionaryObject(COSName.RESOURCES, COSDictionary.class)).filter(Objects::nonNull)
.collect(Collectors.toSet());
cleanResources(formsResources);
}
private void cleanResources(Set resources) {
cleanXObject(resources.stream().map(d -> d.getDictionaryObject(COSName.XOBJECT, COSDictionary.class))
.filter(Objects::nonNull));
cleanFonts(resources.stream().map(d -> d.getDictionaryObject(COSName.FONT, COSDictionary.class))
.filter(Objects::nonNull));
}
private void cleanXObject(Stream xobjects) {
xobjects.forEach(x -> {
Set toRemove = x.entrySet().stream()
.filter(e -> !(e.getValue().getCOSObject() instanceof ReadOnlyFilteredCOSStream))
.filter(e -> e.getValue().getCOSObject() instanceof COSStream).map(e -> e.getKey())
.collect(Collectors.toSet());
LOG.trace("Removing {} xobjects from {}", toRemove.size(), x);
toRemove.stream().forEach(x::removeItem);
});
}
private void cleanFonts(Stream fonts) {
fonts.forEach(f -> {
Set toRemove = f.entrySet().stream()
.filter(e -> !(e.getValue().getCOSObject() instanceof InUseFontDictionary)).map(e -> e.getKey())
.collect(Collectors.toSet());
LOG.trace("Removing {} fonts from {}", toRemove.size(), f);
toRemove.stream().forEach(f::removeItem);
});
}
}
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