1 | /*
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2 | * Copyright 2002-2016 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 | * https://drewnoakes.com/code/exif/
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19 | * https://github.com/drewnoakes/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.util.*;
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27 |
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28 | /**
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29 | * Holds a collection of JPEG data segments. This need not necessarily be all segments
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30 | * within the JPEG. For example, it may be convenient to store only the non-image
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31 | * segments when analysing metadata.
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32 | * <p>
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33 | * Segments are keyed via their {@link JpegSegmentType}. Where multiple segments use the
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34 | * same segment type, they will all be stored and available.
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35 | * <p>
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36 | * Each segment type may contain multiple entries. Conceptually the model is:
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37 | * <code>Map<JpegSegmentType, Collection<byte[]>></code>. This class provides
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38 | * convenience methods around that structure.
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39 | *
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40 | * @author Drew Noakes https://drewnoakes.com
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41 | */
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42 | public class JpegSegmentData
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43 | {
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44 | // TODO key this on JpegSegmentType rather than Byte, and hopefully lose much of the use of 'byte' with this class
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45 | @NotNull
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46 | private final HashMap<Byte, List<byte[]>> _segmentDataMap = new HashMap<Byte, List<byte[]>>(10);
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47 |
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48 | /**
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49 | * Adds segment bytes to the collection.
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50 | *
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51 | * @param segmentType the type of the segment being added
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52 | * @param segmentBytes the byte array holding data for the segment being added
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53 | */
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54 | public void addSegment(byte segmentType, @NotNull byte[] segmentBytes)
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55 | {
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56 | getOrCreateSegmentList(segmentType).add(segmentBytes);
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57 | }
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58 |
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59 | /**
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60 | * Gets the set of JPEG segment type identifiers.
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61 | */
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62 | public Iterable<JpegSegmentType> getSegmentTypes()
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63 | {
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64 | Set<JpegSegmentType> segmentTypes = new HashSet<JpegSegmentType>();
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65 |
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66 | for (Byte segmentTypeByte : _segmentDataMap.keySet())
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67 | {
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68 | JpegSegmentType segmentType = JpegSegmentType.fromByte(segmentTypeByte);
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69 | if (segmentType == null) {
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70 | throw new IllegalStateException("Should not have a segmentTypeByte that is not in the enum: " + Integer.toHexString(segmentTypeByte));
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71 | }
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72 | segmentTypes.add(segmentType);
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73 | }
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74 |
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75 | return segmentTypes;
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76 | }
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77 |
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78 | /**
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79 | * Gets the first JPEG segment data for the specified type.
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80 | *
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81 | * @param segmentType the JpegSegmentType for the desired segment
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82 | * @return a byte[] containing segment data or null if no data exists for that segment
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83 | */
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84 | @Nullable
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85 | public byte[] getSegment(byte segmentType)
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86 | {
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87 | return getSegment(segmentType, 0);
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88 | }
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89 |
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90 | /**
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91 | * Gets the first JPEG segment data for the specified type.
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92 | *
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93 | * @param segmentType the JpegSegmentType for the desired segment
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94 | * @return a byte[] containing segment data or null if no data exists for that segment
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95 | */
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96 | @Nullable
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97 | public byte[] getSegment(@NotNull JpegSegmentType segmentType)
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98 | {
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99 | return getSegment(segmentType.byteValue, 0);
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100 | }
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101 |
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102 | /**
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103 | * Gets segment data for a specific occurrence and type. Use this method when more than one occurrence
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104 | * of segment data for a given type exists.
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105 | *
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106 | * @param segmentType identifies the required segment
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107 | * @param occurrence the zero-based index of the occurrence
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108 | * @return the segment data as a byte[], or null if no segment exists for the type & occurrence
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109 | */
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110 | @Nullable
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111 | public byte[] getSegment(@NotNull JpegSegmentType segmentType, int occurrence)
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112 | {
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113 | return getSegment(segmentType.byteValue, occurrence);
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114 | }
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115 |
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116 | /**
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117 | * Gets segment data for a specific occurrence and type. Use this method when more than one occurrence
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118 | * of segment data for a given type exists.
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119 | *
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120 | * @param segmentType identifies the required segment
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121 | * @param occurrence the zero-based index of the occurrence
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122 | * @return the segment data as a byte[], or null if no segment exists for the type & occurrence
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123 | */
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124 | @Nullable
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125 | public byte[] getSegment(byte segmentType, int occurrence)
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126 | {
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127 | final List<byte[]> segmentList = getSegmentList(segmentType);
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128 |
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129 | return segmentList != null && segmentList.size() > occurrence
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130 | ? segmentList.get(occurrence)
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131 | : null;
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132 | }
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133 |
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134 | /**
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135 | * Returns all instances of a given JPEG segment. If no instances exist, an empty sequence is returned.
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136 | *
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137 | * @param segmentType a number which identifies the type of JPEG segment being queried
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138 | * @return zero or more byte arrays, each holding the data of a JPEG segment
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139 | */
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140 | @NotNull
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141 | public Iterable<byte[]> getSegments(@NotNull JpegSegmentType segmentType)
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142 | {
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143 | return getSegments(segmentType.byteValue);
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144 | }
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145 |
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146 | /**
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147 | * Returns all instances of a given JPEG segment. If no instances exist, an empty sequence is returned.
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148 | *
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149 | * @param segmentType a number which identifies the type of JPEG segment being queried
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150 | * @return zero or more byte arrays, each holding the data of a JPEG segment
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151 | */
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152 | @NotNull
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153 | public Iterable<byte[]> getSegments(byte segmentType)
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154 | {
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155 | final List<byte[]> segmentList = getSegmentList(segmentType);
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156 | return segmentList == null ? new ArrayList<byte[]>() : segmentList;
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157 | }
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158 |
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159 | @Nullable
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160 | private List<byte[]> getSegmentList(byte segmentType)
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161 | {
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162 | return _segmentDataMap.get(segmentType);
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163 | }
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164 |
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165 | @NotNull
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166 | private List<byte[]> getOrCreateSegmentList(byte segmentType)
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167 | {
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168 | List<byte[]> segmentList;
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169 | if (_segmentDataMap.containsKey(segmentType)) {
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170 | segmentList = _segmentDataMap.get(segmentType);
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171 | } else {
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172 | segmentList = new ArrayList<byte[]>();
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173 | _segmentDataMap.put(segmentType, segmentList);
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174 | }
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175 | return segmentList;
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176 | }
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177 |
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178 | /**
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179 | * Returns the count of segment data byte arrays stored for a given segment type.
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180 | *
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181 | * @param segmentType identifies the required segment
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182 | * @return the segment count (zero if no segments exist).
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183 | */
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184 | public int getSegmentCount(@NotNull JpegSegmentType segmentType)
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185 | {
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186 | return getSegmentCount(segmentType.byteValue);
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187 | }
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188 |
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189 | /**
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190 | * Returns the count of segment data byte arrays stored for a given segment type.
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191 | *
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192 | * @param segmentType identifies the required segment
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193 | * @return the segment count (zero if no segments exist).
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194 | */
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195 | public int getSegmentCount(byte segmentType)
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196 | {
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197 | final List<byte[]> segmentList = getSegmentList(segmentType);
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198 | return segmentList == null ? 0 : segmentList.size();
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199 | }
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200 |
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201 | /**
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202 | * Removes a specified instance of a segment's data from the collection. Use this method when more than one
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203 | * occurrence of segment data exists for a given type exists.
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204 | *
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205 | * @param segmentType identifies the required segment
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206 | * @param occurrence the zero-based index of the segment occurrence to remove.
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207 | */
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208 | public void removeSegmentOccurrence(@NotNull JpegSegmentType segmentType, int occurrence)
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209 | {
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210 | removeSegmentOccurrence(segmentType.byteValue, occurrence);
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211 | }
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212 |
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213 | /**
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214 | * Removes a specified instance of a segment's data from the collection. Use this method when more than one
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215 | * occurrence of segment data exists for a given type exists.
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216 | *
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217 | * @param segmentType identifies the required segment
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218 | * @param occurrence the zero-based index of the segment occurrence to remove.
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219 | */
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220 | public void removeSegmentOccurrence(byte segmentType, int occurrence)
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221 | {
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222 | final List<byte[]> segmentList = _segmentDataMap.get(segmentType);
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223 | segmentList.remove(occurrence);
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224 | }
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225 |
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226 | /**
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227 | * Removes all segments from the collection having the specified type.
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228 | *
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229 | * @param segmentType identifies the required segment
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230 | */
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231 | public void removeSegment(@NotNull JpegSegmentType segmentType)
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232 | {
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233 | removeSegment(segmentType.byteValue);
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234 | }
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235 |
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236 | /**
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237 | * Removes all segments from the collection having the specified type.
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238 | *
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239 | * @param segmentType identifies the required segment
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240 | */
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241 | public void removeSegment(byte segmentType)
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242 | {
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243 | _segmentDataMap.remove(segmentType);
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244 | }
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245 |
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246 | /**
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247 | * Determines whether data is present for a given segment type.
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248 | *
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249 | * @param segmentType identifies the required segment
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250 | * @return true if data exists, otherwise false
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251 | */
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252 | public boolean containsSegment(@NotNull JpegSegmentType segmentType)
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253 | {
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254 | return containsSegment(segmentType.byteValue);
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255 | }
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256 |
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257 | /**
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258 | * Determines whether data is present for a given segment type.
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259 | *
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260 | * @param segmentType identifies the required segment
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261 | * @return true if data exists, otherwise false
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262 | */
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263 | public boolean containsSegment(byte segmentType)
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264 | {
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265 | return _segmentDataMap.containsKey(segmentType);
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266 | }
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267 | }
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