1 | /*
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2 | * JpegSegmentReader.java
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3 | *
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4 | * This class written by Drew Noakes, in accordance with the Jpeg specification.
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5 | *
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6 | * This is public domain software - that is, you can do whatever you want
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7 | * with it, and include it software that is licensed under the GNU or the
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8 | * BSD license, or whatever other licence you choose, including proprietary
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9 | * closed source licenses. I do ask that you leave this header in tact.
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10 | *
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11 | * If you make modifications to this code that you think would benefit the
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12 | * wider community, please send me a copy and I'll post it on my site.
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13 | *
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14 | * If you make use of this code, I'd appreciate hearing about it.
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15 | * drew@drewnoakes.com
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16 | * Latest version of this software kept at
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17 | * http://drewnoakes.com/
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18 | *
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19 | * Created by dnoakes on 04-Nov-2002 00:54:00 using IntelliJ IDEA
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20 | */
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21 | package com.drew.imaging.jpeg;
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22 |
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23 | import java.io.*;
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24 |
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25 | /**
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26 | * Performs read functions of Jpeg files, returning specific file segments.
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27 | * TODO add a findAvailableSegments() method
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28 | * TODO add more segment identifiers
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29 | * TODO add a getSegmentDescription() method, returning for example 'App1 application data segment, commonly containing Exif data'
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30 | * @author Drew Noakes http://drewnoakes.com
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31 | */
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32 | public class JpegSegmentReader
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33 | {
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34 | // Jpeg data can be sourced from either a file, byte[] or InputStream
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35 |
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36 | /** Jpeg file */
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37 | private final File _file;
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38 | /** Jpeg data as byte array */
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39 | private final byte[] _data;
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40 | /** Jpeg data as an InputStream */
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41 | private final InputStream _stream;
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42 |
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43 | private JpegSegmentData _segmentData;
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44 |
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45 | /**
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46 | * Private, because this segment crashes my algorithm, and searching for
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47 | * it doesn't work (yet).
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48 | */
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49 | private static final byte SEGMENT_SOS = (byte)0xDA;
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50 |
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51 | /**
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52 | * Private, because one wouldn't search for it.
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53 | */
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54 | private static final byte MARKER_EOI = (byte)0xD9;
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55 |
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56 | /** APP0 Jpeg segment identifier -- Jfif data. */
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57 | public static final byte SEGMENT_APP0 = (byte)0xE0;
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58 | /** APP1 Jpeg segment identifier -- where Exif data is kept. */
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59 | public static final byte SEGMENT_APP1 = (byte)0xE1;
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60 | /** APP2 Jpeg segment identifier. */
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61 | public static final byte SEGMENT_APP2 = (byte)0xE2;
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62 | /** APP3 Jpeg segment identifier. */
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63 | public static final byte SEGMENT_APP3 = (byte)0xE3;
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64 | /** APP4 Jpeg segment identifier. */
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65 | public static final byte SEGMENT_APP4 = (byte)0xE4;
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66 | /** APP5 Jpeg segment identifier. */
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67 | public static final byte SEGMENT_APP5 = (byte)0xE5;
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68 | /** APP6 Jpeg segment identifier. */
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69 | public static final byte SEGMENT_APP6 = (byte)0xE6;
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70 | /** APP7 Jpeg segment identifier. */
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71 | public static final byte SEGMENT_APP7 = (byte)0xE7;
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72 | /** APP8 Jpeg segment identifier. */
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73 | public static final byte SEGMENT_APP8 = (byte)0xE8;
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74 | /** APP9 Jpeg segment identifier. */
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75 | public static final byte SEGMENT_APP9 = (byte)0xE9;
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76 | /** APPA Jpeg segment identifier -- can hold Unicode comments. */
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77 | public static final byte SEGMENT_APPA = (byte)0xEA;
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78 | /** APPB Jpeg segment identifier. */
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79 | public static final byte SEGMENT_APPB = (byte)0xEB;
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80 | /** APPC Jpeg segment identifier. */
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81 | public static final byte SEGMENT_APPC = (byte)0xEC;
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82 | /** APPD Jpeg segment identifier -- IPTC data in here. */
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83 | public static final byte SEGMENT_APPD = (byte)0xED;
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84 | /** APPE Jpeg segment identifier. */
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85 | public static final byte SEGMENT_APPE = (byte)0xEE;
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86 | /** APPF Jpeg segment identifier. */
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87 | public static final byte SEGMENT_APPF = (byte)0xEF;
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88 | /** Start Of Image segment identifier. */
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89 | public static final byte SEGMENT_SOI = (byte)0xD8;
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90 | /** Define Quantization Table segment identifier. */
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91 | public static final byte SEGMENT_DQT = (byte)0xDB;
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92 | /** Define Huffman Table segment identifier. */
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93 | public static final byte SEGMENT_DHT = (byte)0xC4;
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94 | /** Start-of-Frame Zero segment identifier. */
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95 | public static final byte SEGMENT_SOF0 = (byte)0xC0;
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96 | /** Jpeg comment segment identifier. */
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97 | public static final byte SEGMENT_COM = (byte)0xFE;
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98 |
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99 | /**
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100 | * Creates a JpegSegmentReader for a specific file.
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101 | * @param file the Jpeg file to read segments from
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102 | */
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103 | public JpegSegmentReader(File file) throws JpegProcessingException
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104 | {
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105 | _file = file;
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106 | _data = null;
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107 | _stream = null;
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108 |
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109 | readSegments();
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110 | }
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111 |
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112 | /**
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113 | * Creates a JpegSegmentReader for a byte array.
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114 | * @param fileContents the byte array containing Jpeg data
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115 | */
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116 | public JpegSegmentReader(byte[] fileContents) throws JpegProcessingException
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117 | {
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118 | _file = null;
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119 | _data = fileContents;
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120 | _stream = null;
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121 |
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122 | readSegments();
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123 | }
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124 |
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125 | public JpegSegmentReader(InputStream in) throws JpegProcessingException
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126 | {
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127 | _stream = in;
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128 | _file = null;
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129 | _data = null;
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130 |
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131 | readSegments();
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132 | }
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133 |
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134 | public JpegSegmentReader(JpegSegmentData segmentData)
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135 | {
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136 | _file = null;
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137 | _data = null;
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138 | _stream = null;
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139 |
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140 | _segmentData = segmentData;
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141 | }
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142 |
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143 | /**
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144 | * Reads the first instance of a given Jpeg segment, returning the contents as
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145 | * a byte array.
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146 | * @param segmentMarker the byte identifier for the desired segment
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147 | * @return the byte array if found, else null
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148 | * @throws JpegProcessingException for any problems processing the Jpeg data,
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149 | * including inner IOExceptions
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150 | */
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151 | public byte[] readSegment(byte segmentMarker) throws JpegProcessingException
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152 | {
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153 | return readSegment(segmentMarker, 0);
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154 | }
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155 |
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156 | /**
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157 | * Reads the first instance of a given Jpeg segment, returning the contents as
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158 | * a byte array.
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159 | * @param segmentMarker the byte identifier for the desired segment
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160 | * @param occurrence the occurrence of the specified segment within the jpeg file
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161 | * @return the byte array if found, else null
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162 | */
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163 | public byte[] readSegment(byte segmentMarker, int occurrence)
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164 | {
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165 | return _segmentData.getSegment(segmentMarker, occurrence);
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166 | }
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167 |
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168 | public final int getSegmentCount(byte segmentMarker)
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169 | {
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170 | return _segmentData.getSegmentCount(segmentMarker);
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171 | }
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172 |
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173 | public final JpegSegmentData getSegmentData()
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174 | {
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175 | return _segmentData;
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176 | }
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177 |
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178 | private void readSegments() throws JpegProcessingException
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179 | {
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180 | _segmentData = new JpegSegmentData();
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181 |
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182 | BufferedInputStream inStream = getJpegInputStream();
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183 | try {
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184 | int offset = 0;
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185 | // first two bytes should be jpeg magic number
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186 | if (!isValidJpegHeaderBytes(inStream)) {
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187 | throw new JpegProcessingException("not a jpeg file");
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188 | }
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189 | offset += 2;
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190 | do {
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191 | // next byte is 0xFF
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192 | byte segmentIdentifier = (byte)(inStream.read() & 0xFF);
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193 | if ((segmentIdentifier & 0xFF) != 0xFF) {
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194 | throw new JpegProcessingException("expected jpeg segment start identifier 0xFF at offset " + offset + ", not 0x" + Integer.toHexString(segmentIdentifier & 0xFF));
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195 | }
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196 | offset++;
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197 | // next byte is <segment-marker>
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198 | byte thisSegmentMarker = (byte)(inStream.read() & 0xFF);
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199 | offset++;
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200 | // next 2-bytes are <segment-size>: [high-byte] [low-byte]
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201 | byte[] segmentLengthBytes = new byte[2];
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202 | inStream.read(segmentLengthBytes, 0, 2);
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203 | offset += 2;
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204 | int segmentLength = ((segmentLengthBytes[0] << 8) & 0xFF00) | (segmentLengthBytes[1] & 0xFF);
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205 | // segment length includes size bytes, so subtract two
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206 | segmentLength -= 2;
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207 | if (segmentLength > inStream.available())
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208 | throw new JpegProcessingException("segment size would extend beyond file stream length");
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209 | else if (segmentLength < 0)
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210 | throw new JpegProcessingException("segment size would be less than zero");
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211 | byte[] segmentBytes = new byte[segmentLength];
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212 | inStream.read(segmentBytes, 0, segmentLength);
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213 | offset += segmentLength;
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214 | if ((thisSegmentMarker & 0xFF) == (SEGMENT_SOS & 0xFF)) {
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215 | // The 'Start-Of-Scan' segment's length doesn't include the image data, instead would
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216 | // have to search for the two bytes: 0xFF 0xD9 (EOI).
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217 | // It comes last so simply return at this point
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218 | return;
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219 | } else if ((thisSegmentMarker & 0xFF) == (MARKER_EOI & 0xFF)) {
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220 | // the 'End-Of-Image' segment -- this should never be found in this fashion
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221 | return;
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222 | } else {
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223 | _segmentData.addSegment(thisSegmentMarker, segmentBytes);
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224 | }
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225 | // didn't find the one we're looking for, loop through to the next segment
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226 | } while (true);
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227 | } catch (IOException ioe) {
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228 | //throw new JpegProcessingException("IOException processing Jpeg file", ioe);
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229 | throw new JpegProcessingException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);
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230 | } finally {
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231 | try {
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232 | if (inStream != null) {
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233 | inStream.close();
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234 | }
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235 | } catch (IOException ioe) {
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236 | //throw new JpegProcessingException("IOException processing Jpeg file", ioe);
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237 | throw new JpegProcessingException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);
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238 | }
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239 | }
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240 | }
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241 |
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242 | /**
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243 | * Private helper method to create a BufferedInputStream of Jpeg data from whichever
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244 | * data source was specified upon construction of this instance.
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245 | * @return a a BufferedInputStream of Jpeg data
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246 | * @throws JpegProcessingException for any problems obtaining the stream
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247 | */
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248 | private BufferedInputStream getJpegInputStream() throws JpegProcessingException
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249 | {
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250 | if (_stream!=null) {
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251 | if (_stream instanceof BufferedInputStream) {
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252 | return (BufferedInputStream) _stream;
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253 | } else {
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254 | return new BufferedInputStream(_stream);
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255 | }
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256 | }
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257 | InputStream inputStream;
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258 | if (_data == null) {
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259 | try {
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260 | inputStream = new FileInputStream(_file);
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261 | } catch (FileNotFoundException e) {
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262 | throw new JpegProcessingException("Jpeg file does not exist", e);
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263 | }
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264 | } else {
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265 | inputStream = new ByteArrayInputStream(_data);
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266 | }
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267 | return new BufferedInputStream(inputStream);
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268 | }
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269 |
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270 | /**
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271 | * Helper method that validates the Jpeg file's magic number.
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272 | * @param fileStream the InputStream to read bytes from, which must be positioned
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273 | * at its start (i.e. no bytes read yet)
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274 | * @return true if the magic number is Jpeg (0xFFD8)
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275 | * @throws IOException for any problem in reading the file
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276 | */
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277 | private boolean isValidJpegHeaderBytes(InputStream fileStream) throws IOException
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278 | {
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279 | byte[] header = new byte[2];
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280 | fileStream.read(header, 0, 2);
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281 | return (header[0] & 0xFF) == 0xFF && (header[1] & 0xFF) == 0xD8;
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282 | }
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283 | }
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