org.openpdf.renderer.PDFXref Maven / Gradle / Ivy
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/*
* Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
* Santa Clara, California 95054, U.S.A. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.openpdf.renderer;
import java.lang.ref.SoftReference;
/**
* a cross reference representing a line in the PDF cross referencing
* table.
*
* There are two forms of the PDFXref, destinguished by absolutely nothing.
* The first type of PDFXref is used as indirect references in a PDFObject.
* In this type, the id is an index number into the object cross reference
* table. The id will range from 0 to the size of the cross reference
* table.
*
* The second form is used in the Java representation of the cross reference
* table. In this form, the id is the file position of the start of the
* object in the PDF file. See the use of both of these in the
* PDFFile.dereference() method, which takes a PDFXref of the first form,
* and uses (internally) a PDFXref of the second form.
*
* This is an unhappy state of affairs, and should be fixed. Fortunatly,
* the two uses have already been factored out as two different methods.
*
* @author Mike Wessler
*/
public class PDFXref {
private int id;
private int generation;
private final boolean compressed;
// this field is only used in PDFFile.objIdx
private SoftReference reference = null;
/**
* create a new PDFXref, given a parsed id and generation.
*/
public PDFXref(int id, int gen) {
this.id = id;
this.generation = gen;
this.compressed = false;
}
/**
* create a new PDFXref, given a parsed id, compressedObjId and index
*/
public PDFXref(int id, int gen, boolean compressed) {
this.id = id;
this.generation = gen;
this.compressed = compressed;
}
/**
* create a new PDFXref, given a sequence of bytes representing the
* fixed-width cross reference table line
*/
public PDFXref(byte[] line) {
if (line == null) {
this.id = -1;
this.generation = -1;
} else {
this.id = Integer.parseInt(new String(line, 0, 10).trim());
this.generation = Integer.parseInt(new String(line, 11, 5).trim());
}
this.compressed = false;
}
/**
* get the character index into the file of the start of this object
*/
public int getFilePos() {
return this.id;
}
/**
* get the generation of this object
*/
public int getGeneration() {
return this.generation;
}
/**
* get the generation of this object
*/
public int getIndex() {
return this.generation;
}
/**
* get the object number of this object
*/
public int getID() {
return this.id;
}
/**
* get compressed flag of this object
*/
public boolean getCompressed() {
return this.compressed;
}
/**
* Get the object this reference refers to, or null if it hasn't been
* set.
* @return the object if it exists, or null if not
*/
public PDFObject getObject() {
if (this.reference != null) {
return this.reference.get();
}
return null;
}
/**
* Set the object this reference refers to.
*/
public void setObject(PDFObject obj) {
this.reference = new SoftReference(obj);
}
@Override
public boolean equals(Object obj) {
return (obj instanceof PDFXref) &&
((PDFXref)obj).id == id &&
((PDFXref)obj).generation == generation;
}
@Override
public int hashCode() {
return id ^ (generation << 8);
}
}