1 | /*
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2 | * Copyright 2002-2012 Drew Noakes
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | * More information about this project is available at:
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17 | *
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18 | * http://drewnoakes.com/code/exif/
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19 | * http://code.google.com/p/metadata-extractor/
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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 com.drew.lang.annotations.NotNull;
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24 | import com.drew.lang.annotations.Nullable;
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25 |
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26 | import java.io.*;
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27 |
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28 | /**
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29 | * Performs read functions of Jpeg files, returning specific file segments.
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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 | // TODO add a findAvailableSegments() method
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35 | // TODO add more segment identifiers
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36 | // TODO add a getSegmentDescription() method, returning for example 'App1 application data segment, commonly containing Exif data'
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37 |
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38 | @NotNull
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39 | private final JpegSegmentData _segmentData;
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40 |
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41 | /**
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42 | * Private, because this segment crashes my algorithm, and searching for it doesn't work (yet).
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43 | */
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44 | private static final byte SEGMENT_SOS = (byte)0xDA;
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45 |
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46 | /**
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47 | * Private, because one wouldn't search for it.
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48 | */
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49 | private static final byte MARKER_EOI = (byte)0xD9;
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50 |
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51 | /** APP0 Jpeg segment identifier -- JFIF data (also JFXX apparently). */
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52 | public static final byte SEGMENT_APP0 = (byte)0xE0;
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53 | /** APP1 Jpeg segment identifier -- where Exif data is kept. XMP data is also kept in here, though usually in a second instance. */
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54 | public static final byte SEGMENT_APP1 = (byte)0xE1;
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55 | /** APP2 Jpeg segment identifier. */
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56 | public static final byte SEGMENT_APP2 = (byte)0xE2;
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57 | /** APP3 Jpeg segment identifier. */
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58 | public static final byte SEGMENT_APP3 = (byte)0xE3;
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59 | /** APP4 Jpeg segment identifier. */
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60 | public static final byte SEGMENT_APP4 = (byte)0xE4;
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61 | /** APP5 Jpeg segment identifier. */
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62 | public static final byte SEGMENT_APP5 = (byte)0xE5;
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63 | /** APP6 Jpeg segment identifier. */
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64 | public static final byte SEGMENT_APP6 = (byte)0xE6;
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65 | /** APP7 Jpeg segment identifier. */
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66 | public static final byte SEGMENT_APP7 = (byte)0xE7;
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67 | /** APP8 Jpeg segment identifier. */
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68 | public static final byte SEGMENT_APP8 = (byte)0xE8;
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69 | /** APP9 Jpeg segment identifier. */
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70 | public static final byte SEGMENT_APP9 = (byte)0xE9;
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71 | /** APPA (App10) Jpeg segment identifier -- can hold Unicode comments. */
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72 | public static final byte SEGMENT_APPA = (byte)0xEA;
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73 | /** APPB (App11) Jpeg segment identifier. */
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74 | public static final byte SEGMENT_APPB = (byte)0xEB;
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75 | /** APPC (App12) Jpeg segment identifier. */
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76 | public static final byte SEGMENT_APPC = (byte)0xEC;
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77 | /** APPD (App13) Jpeg segment identifier -- IPTC data in here. */
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78 | public static final byte SEGMENT_APPD = (byte)0xED;
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79 | /** APPE (App14) Jpeg segment identifier. */
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80 | public static final byte SEGMENT_APPE = (byte)0xEE;
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81 | /** APPF (App15) Jpeg segment identifier. */
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82 | public static final byte SEGMENT_APPF = (byte)0xEF;
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83 | /** Start Of Image segment identifier. */
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84 | public static final byte SEGMENT_SOI = (byte)0xD8;
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85 | /** Define Quantization Table segment identifier. */
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86 | public static final byte SEGMENT_DQT = (byte)0xDB;
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87 | /** Define Huffman Table segment identifier. */
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88 | public static final byte SEGMENT_DHT = (byte)0xC4;
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89 | /** Start-of-Frame Zero segment identifier. */
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90 | public static final byte SEGMENT_SOF0 = (byte)0xC0;
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91 | /** Jpeg comment segment identifier. */
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92 | public static final byte SEGMENT_COM = (byte)0xFE;
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93 |
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94 | /**
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95 | * Creates a JpegSegmentReader for a specific file.
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96 | * @param file the Jpeg file to read segments from
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97 | */
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98 | @SuppressWarnings({ "ConstantConditions" })
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99 | public JpegSegmentReader(@NotNull File file) throws JpegProcessingException, IOException
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100 | {
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101 | if (file==null)
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102 | throw new NullPointerException();
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103 |
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104 | InputStream inputStream = null;
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105 | try {
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106 | inputStream = new FileInputStream(file);
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107 | _segmentData = readSegments(new BufferedInputStream(inputStream), false);
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108 | } finally {
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109 | if (inputStream != null)
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110 | inputStream.close();
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111 | }
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112 | }
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113 |
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114 | /**
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115 | * Creates a JpegSegmentReader for a byte array.
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116 | * @param fileContents the byte array containing Jpeg data
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117 | */
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118 | @SuppressWarnings({ "ConstantConditions" })
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119 | public JpegSegmentReader(@NotNull byte[] fileContents) throws JpegProcessingException
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120 | {
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121 | if (fileContents==null)
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122 | throw new NullPointerException();
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123 |
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124 | BufferedInputStream stream = new BufferedInputStream(new ByteArrayInputStream(fileContents));
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125 | _segmentData = readSegments(stream, false);
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126 | }
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127 |
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128 | /**
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129 | * Creates a JpegSegmentReader for an InputStream.
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130 | * @param inputStream the InputStream containing Jpeg data
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131 | */
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132 | @SuppressWarnings({ "ConstantConditions" })
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133 | public JpegSegmentReader(@NotNull InputStream inputStream, boolean waitForBytes) throws JpegProcessingException
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134 | {
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135 | if (inputStream==null)
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136 | throw new NullPointerException();
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137 |
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138 | BufferedInputStream bufferedInputStream = inputStream instanceof BufferedInputStream
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139 | ? (BufferedInputStream)inputStream
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140 | : new BufferedInputStream(inputStream);
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141 |
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142 | _segmentData = readSegments(bufferedInputStream, waitForBytes);
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143 | }
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144 |
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145 | /**
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146 | * Reads the first instance of a given Jpeg segment, returning the contents as
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147 | * a byte array.
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148 | * @param segmentMarker the byte identifier for the desired segment
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149 | * @return the byte array if found, else null
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150 | */
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151 | @Nullable
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152 | public byte[] readSegment(byte segmentMarker)
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153 | {
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154 | return readSegment(segmentMarker, 0);
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155 | }
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156 |
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157 | /**
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158 | * Reads the Nth instance of a given Jpeg segment, returning the contents as a byte array.
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159 | *
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160 | * @param segmentMarker the byte identifier for the desired segment
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161 | * @param occurrence the occurrence of the specified segment within the jpeg file
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162 | * @return the byte array if found, else null
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163 | */
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164 | @Nullable
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165 | public byte[] readSegment(byte segmentMarker, int occurrence)
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166 | {
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167 | return _segmentData.getSegment(segmentMarker, occurrence);
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168 | }
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169 |
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170 | /**
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171 | * Returns all instances of a given Jpeg segment. If no instances exist, an empty sequence is returned.
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172 | *
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173 | * @param segmentMarker a number which identifies the type of Jpeg segment being queried
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174 | * @return zero or more byte arrays, each holding the data of a Jpeg segment
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175 | */
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176 | @NotNull
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177 | public Iterable<byte[]> readSegments(byte segmentMarker)
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178 | {
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179 | return _segmentData.getSegments(segmentMarker);
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180 | }
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181 |
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182 | /**
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183 | * Returns the number of segments having the specified JPEG segment marker.
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184 | * @param segmentMarker the JPEG segment identifying marker.
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185 | * @return the count of matching segments.
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186 | */
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187 | public final int getSegmentCount(byte segmentMarker)
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188 | {
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189 | return _segmentData.getSegmentCount(segmentMarker);
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190 | }
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191 |
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192 | /**
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193 | * Returns the JpegSegmentData object used by this reader.
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194 | * @return the JpegSegmentData object.
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195 | */
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196 | @NotNull
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197 | public final JpegSegmentData getSegmentData()
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198 | {
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199 | return _segmentData;
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200 | }
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201 |
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202 | @NotNull
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203 | private JpegSegmentData readSegments(@NotNull final BufferedInputStream jpegInputStream, boolean waitForBytes) throws JpegProcessingException
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204 | {
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205 | JpegSegmentData segmentData = new JpegSegmentData();
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206 |
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207 | try {
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208 | int offset = 0;
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209 | // first two bytes should be jpeg magic number
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210 | byte[] headerBytes = new byte[2];
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211 | if (jpegInputStream.read(headerBytes, 0, 2)!=2)
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212 | throw new JpegProcessingException("not a jpeg file");
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213 | final boolean hasValidHeader = (headerBytes[0] & 0xFF) == 0xFF && (headerBytes[1] & 0xFF) == 0xD8;
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214 | if (!hasValidHeader)
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215 | throw new JpegProcessingException("not a jpeg file");
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216 |
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217 | offset += 2;
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218 | do {
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219 | // need four bytes from stream for segment header before continuing
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220 | if (!checkForBytesOnStream(jpegInputStream, 4, waitForBytes))
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221 | throw new JpegProcessingException("stream ended before segment header could be read");
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222 |
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223 | // next byte is 0xFF
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224 | byte segmentIdentifier = (byte)(jpegInputStream.read() & 0xFF);
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225 | if ((segmentIdentifier & 0xFF) != 0xFF) {
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226 | throw new JpegProcessingException("expected jpeg segment start identifier 0xFF at offset " + offset + ", not 0x" + Integer.toHexString(segmentIdentifier & 0xFF));
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227 | }
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228 | offset++;
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229 | // next byte is <segment-marker>
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230 | byte thisSegmentMarker = (byte)(jpegInputStream.read() & 0xFF);
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231 | offset++;
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232 | // next 2-bytes are <segment-size>: [high-byte] [low-byte]
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233 | byte[] segmentLengthBytes = new byte[2];
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234 | if (jpegInputStream.read(segmentLengthBytes, 0, 2) != 2)
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235 | throw new JpegProcessingException("Jpeg data ended unexpectedly.");
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236 | offset += 2;
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237 | int segmentLength = ((segmentLengthBytes[0] << 8) & 0xFF00) | (segmentLengthBytes[1] & 0xFF);
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238 | // segment length includes size bytes, so subtract two
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239 | segmentLength -= 2;
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240 | if (!checkForBytesOnStream(jpegInputStream, segmentLength, waitForBytes))
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241 | throw new JpegProcessingException("segment size would extend beyond file stream length");
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242 | if (segmentLength < 0)
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243 | throw new JpegProcessingException("segment size would be less than zero");
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244 | byte[] segmentBytes = new byte[segmentLength];
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245 | if (jpegInputStream.read(segmentBytes, 0, segmentLength) != segmentLength)
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246 | throw new JpegProcessingException("Jpeg data ended unexpectedly.");
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247 | offset += segmentLength;
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248 | if ((thisSegmentMarker & 0xFF) == (SEGMENT_SOS & 0xFF)) {
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249 | // The 'Start-Of-Scan' segment's length doesn't include the image data, instead would
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250 | // have to search for the two bytes: 0xFF 0xD9 (EOI).
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251 | // It comes last so simply return at this point
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252 | return segmentData;
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253 | } else if ((thisSegmentMarker & 0xFF) == (MARKER_EOI & 0xFF)) {
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254 | // the 'End-Of-Image' segment -- this should never be found in this fashion
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255 | return segmentData;
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256 | } else {
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257 | segmentData.addSegment(thisSegmentMarker, segmentBytes);
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258 | }
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259 | } while (true);
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260 | } catch (IOException ioe) {
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261 | throw new JpegProcessingException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);
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262 | } finally {
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263 | try {
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264 | if (jpegInputStream != null) {
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265 | jpegInputStream.close();
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266 | }
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267 | } catch (IOException ioe) {
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268 | throw new JpegProcessingException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);
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269 | }
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270 | }
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271 | }
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272 |
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273 | private boolean checkForBytesOnStream(@NotNull BufferedInputStream stream, int bytesNeeded, boolean waitForBytes) throws IOException
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274 | {
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275 | // NOTE waiting is essential for network streams where data can be delayed, but it is not necessary for byte[] or filesystems
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276 |
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277 | if (!waitForBytes)
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278 | return bytesNeeded <= stream.available();
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279 |
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280 | int count = 40; // * 100ms = approx 4 seconds
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281 | while (count > 0) {
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282 | if (bytesNeeded <= stream.available())
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283 | return true;
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284 | try {
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285 | Thread.sleep(100);
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286 | } catch (InterruptedException e) {
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287 | // continue
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288 | }
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289 | count--;
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290 | }
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291 | return false;
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292 | }
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293 | }
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