1 /*
   2  * Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.imageio.plugins.jpeg;
  27 
  28 import javax.imageio.metadata.IIOMetadataNode;
  29 import javax.imageio.stream.ImageOutputStream;
  30 import javax.imageio.metadata.IIOInvalidTreeException;
  31 
  32 import java.io.IOException;
  33 import java.io.UnsupportedEncodingException;
  34 
  35 import org.w3c.dom.Node;
  36 
  37 /**
  38  * A Comment marker segment.  Retains an array of bytes representing the
  39  * comment data as it is read from the stream.  If the marker segment is
  40  * constructed from a String, then local default encoding is assumed
  41  * when creating the byte array.  If the marker segment is created from
  42  * an {@code IIOMetadataNode}, the user object, if present is
  43  * assumed to be a byte array containing the comment data.  If there is
  44  * no user object then the comment attribute is used to create the
  45  * byte array, again assuming the default local encoding.
  46  */
  47 class COMMarkerSegment extends MarkerSegment {
  48     private static final String ENCODING = "ISO-8859-1";
  49 
  50     /**
  51      * Constructs a marker segment from the given buffer, which contains
  52      * data from an {@code ImageInputStream}.  This is used when
  53      * reading metadata from a stream.
  54      */
  55     COMMarkerSegment(JPEGBuffer buffer) throws IOException {
  56         super(buffer);
  57         loadData(buffer);
  58     }
  59 
  60     /**
  61      * Constructs a marker segment from a String.  This is used when
  62      * modifying metadata from a non-native tree and when transcoding.
  63      * The default encoding is used to construct the byte array.
  64      */
  65     COMMarkerSegment(String comment) {
  66         super(JPEG.COM);
  67         data = comment.getBytes(); // Default encoding
  68     }
  69 
  70     /**
  71      * Constructs a marker segment from a native tree node.  If the node
  72      * is an {@code IIOMetadataNode} and contains a user object,
  73      * that object is used rather than the string attribute.  If the
  74      * string attribute is used, the default encoding is used.
  75      */
  76     COMMarkerSegment(Node node) throws IIOInvalidTreeException{
  77         super(JPEG.COM);
  78         if (node instanceof IIOMetadataNode) {
  79             IIOMetadataNode ourNode = (IIOMetadataNode) node;
  80             data = (byte []) ourNode.getUserObject();
  81         }
  82         if (data == null) {
  83             String comment =
  84                 node.getAttributes().getNamedItem("comment").getNodeValue();
  85             if (comment != null) {
  86                 data = comment.getBytes(); // Default encoding
  87             } else {
  88                 throw new IIOInvalidTreeException("Empty comment node!", node);
  89             }
  90         }
  91     }
  92 
  93     /**
  94      * Returns the array encoded as a String, using ISO-Latin-1 encoding.
  95      * If an application needs another encoding, the data array must be
  96      * consulted directly.
  97      */
  98     String getComment() {
  99         try {
 100             return new String (data, ENCODING);
 101         } catch (UnsupportedEncodingException e) {}  // Won't happen
 102         return null;
 103     }
 104 
 105     /**
 106      * Returns an {@code IIOMetadataNode} containing the data array
 107      * as a user object and a string encoded using ISO-8895-1, as an
 108      * attribute.
 109      */
 110     IIOMetadataNode getNativeNode() {
 111         IIOMetadataNode node = new IIOMetadataNode("com");
 112         node.setAttribute("comment", getComment());
 113         if (data != null) {
 114             node.setUserObject(data.clone());
 115         }
 116         return node;
 117     }
 118 
 119     /**
 120      * Writes the data for this segment to the stream in
 121      * valid JPEG format, directly from the data array.
 122      */
 123     void write(ImageOutputStream ios) throws IOException {
 124         length = 2 + data.length;
 125         writeTag(ios);
 126         ios.write(data);
 127     }
 128 
 129     void print() {
 130         printTag("COM");
 131         System.out.println("<" + getComment() + ">");
 132     }
 133 }
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