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annotate org.eclipse.swt.win32.win32.x86/src/org/eclipse/swt/internal/image/PngChunk.d @ 112:9f4c18c268b2

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Update to compile and execute with dmd 2.052.
author kntroh
date Wed, 16 Mar 2011 21:53:53 +0900
parents 0ecb2b338560
children 536e43f63c81
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1 /*******************************************************************************
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2 * Copyright (c) 2000, 2006 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module org.eclipse.swt.internal.image.PngChunk;
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14
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15
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16 import org.eclipse.swt.SWT;
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17 import org.eclipse.swt.internal.image.LEDataInputStream;
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18 import org.eclipse.swt.internal.image.PngFileReadState;
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19 import org.eclipse.swt.internal.image.PngIhdrChunk;
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20 import org.eclipse.swt.internal.image.PngPlteChunk;
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21 import org.eclipse.swt.internal.image.PngIdatChunk;
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22 import org.eclipse.swt.internal.image.PngIendChunk;
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23 import org.eclipse.swt.internal.image.PngTrnsChunk;
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24 import java.lang.all;
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25
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26
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27 class PngChunk {
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28 byte[] reference;
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29
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30 static const int LENGTH_OFFSET = 0;
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31 static const int TYPE_OFFSET = 4;
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32 static const int DATA_OFFSET = 8;
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33
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34 static const int TYPE_FIELD_LENGTH = 4;
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35 static const int LENGTH_FIELD_LENGTH = 4;
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36 static const int MIN_LENGTH = 12;
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37
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38 static const int CHUNK_UNKNOWN = -1;
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39 // Critical chunks.
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40 static const int CHUNK_IHDR = 0;
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41 static const int CHUNK_PLTE = 1;
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42 static const int CHUNK_IDAT = 2;
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43 static const int CHUNK_IEND = 3;
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44 // Non-critical chunks.
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45 static const int CHUNK_tRNS = 5;
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46
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47 static /*const*/ byte[] TYPE_IHDR = cast(byte[])"IHDR";//{(byte) 'I', (byte) 'H', (byte) 'D', (byte) 'R'};
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48 static /*const*/ byte[] TYPE_PLTE = cast(byte[])"PLTE";//{(byte) 'P', (byte) 'L', (byte) 'T', (byte) 'E'};
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49 static /*const*/ byte[] TYPE_IDAT = cast(byte[])"IDAT";//{(byte) 'I', (byte) 'D', (byte) 'A', (byte) 'T'};
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50 static /*const*/ byte[] TYPE_IEND = cast(byte[])"IEND";//{(byte) 'I', (byte) 'E', (byte) 'N', (byte) 'D'};
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51 static /*const*/ byte[] TYPE_tRNS = cast(byte[])"tRNS";//{(byte) 't', (byte) 'R', (byte) 'N', (byte) 'S'};
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52
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53 private static int[] _CRC_TABLE = null;
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54 static int[] CRC_TABLE() {
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55 if (!_CRC_TABLE) static_this();
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56 return _CRC_TABLE;
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57 }
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58 //public static void static_this() {
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59 private static void static_this() {
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60 _CRC_TABLE = new int[256];
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61 for (int i = 0; i < 256; i++) {
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62 _CRC_TABLE[i] = i;
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63 for (int j = 0; j < 8; j++) {
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64 if ((_CRC_TABLE[i] & 0x1) is 0) {
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65 _CRC_TABLE[i] = (_CRC_TABLE[i] >> 1) & 0x7FFFFFFF;
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66 } else {
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67 _CRC_TABLE[i] = 0xEDB88320 ^ ((_CRC_TABLE[i] >> 1) & 0x7FFFFFFF);
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68 }
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69 }
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70 }
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71 }
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72
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73 int length;
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74
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75 /**
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76 * Construct a PngChunk using the reference bytes
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77 * given.
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78 */
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79 this(byte[] reference) {
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80 setReference(reference);
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81 if (reference.length < LENGTH_OFFSET + LENGTH_FIELD_LENGTH) SWT.error(SWT.ERROR_INVALID_IMAGE);
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82 length = getInt32(LENGTH_OFFSET);
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83 }
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84
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85 /**
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86 * Construct a PngChunk with the specified number of
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87 * data bytes.
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88 */
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89 this(int dataLength) {
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90 this(new byte[MIN_LENGTH + dataLength]);
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91 setLength(dataLength);
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92 }
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93
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94 /**
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95 * Get the PngChunk's reference byteArray;
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96 */
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97 byte[] getReference() {
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98 return reference;
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99 }
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100
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101 /**
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102 * Set the PngChunk's reference byteArray;
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103 */
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104 void setReference(byte[] reference) {
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105 this.reference = reference;
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106 }
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107
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108 /**
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109 * Get the 16-bit integer from the reference byte
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110 * array at the given offset.
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111 */
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112 int getInt16(int offset) {
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113 int answer = 0;
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114 answer |= (reference[offset] & 0xFF) << 8;
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115 answer |= (reference[offset + 1] & 0xFF);
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116 return answer;
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117 }
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118
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119 /**
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120 * Set the 16-bit integer in the reference byte
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121 * array at the given offset.
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122 */
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123 void setInt16(int offset, int value) {
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124 reference[offset] = cast(byte) ((value >> 8) & 0xFF);
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125 reference[offset + 1] = cast(byte) (value & 0xFF);
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126 }
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127
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128 /**
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129 * Get the 32-bit integer from the reference byte
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130 * array at the given offset.
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131 */
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132 int getInt32(int offset) {
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133 int answer = 0;
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134 answer |= (reference[offset] & 0xFF) << 24;
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135 answer |= (reference[offset + 1] & 0xFF) << 16;
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136 answer |= (reference[offset + 2] & 0xFF) << 8;
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137 answer |= (reference[offset + 3] & 0xFF);
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138 return answer;
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139 }
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140
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141 /**
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142 * Set the 32-bit integer in the reference byte
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143 * array at the given offset.
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144 */
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145 void setInt32(int offset, int value) {
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146 reference[offset] = cast(byte) ((value >> 24) & 0xFF);
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147 reference[offset + 1] = cast(byte) ((value >> 16) & 0xFF);
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148 reference[offset + 2] = cast(byte) ((value >> 8) & 0xFF);
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149 reference[offset + 3] = cast(byte) (value & 0xFF);
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150 }
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151
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152 /**
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153 * Get the length of the data component of this chunk.
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154 * This is not the length of the entire chunk.
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parents:
diff changeset
155 */
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parents:
diff changeset
156 int getLength() {
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parents:
diff changeset
157 return length;
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parents:
diff changeset
158 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
159
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
160 /**
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
161 * Set the length of the data component of this chunk.
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parents:
diff changeset
162 * This is not the length of the entire chunk.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
163 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
164 void setLength(int value) {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
165 setInt32(LENGTH_OFFSET, value);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
166 length = value;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
167 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
168
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
169 /**
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
170 * Get the chunk type. This is a four byte value.
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parents:
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171 * Each byte should be an ASCII character.
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parents:
diff changeset
172 * The first byte is upper case if the chunk is critical.
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parents:
diff changeset
173 * The second byte is upper case if the chunk is publicly defined.
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parents:
diff changeset
174 * The third byte must be upper case.
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parents:
diff changeset
175 * The fourth byte is upper case if the chunk is unsafe to copy.
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parents:
diff changeset
176 * Public chunk types are defined by the PNG Development Group.
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177 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
178 byte[] getTypeBytes() {
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parents:
diff changeset
179 byte[] type = new byte[4];
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parents:
diff changeset
180 System.arraycopy(reference, TYPE_OFFSET, type, 0, TYPE_FIELD_LENGTH);
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parents:
diff changeset
181 return type;
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182 }
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diff changeset
183
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
184 /**
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parents:
diff changeset
185 * Set the chunk type. This is a four byte value.
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parents:
diff changeset
186 * Each byte should be an ASCII character.
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parents:
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187 * The first byte is upper case if the chunk is critical.
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parents:
diff changeset
188 * The second byte is upper case if the chunk is publicly defined.
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parents:
diff changeset
189 * The third byte must be upper case.
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diff changeset
190 * The fourth byte is upper case if the chunk is unsafe to copy.
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191 * Public chunk types are defined by the PNG Development Group.
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192 */
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diff changeset
193 void setType(byte[] value) {
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diff changeset
194 if (value.length !is TYPE_FIELD_LENGTH) {
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parents:
diff changeset
195 SWT.error (SWT.ERROR_INVALID_ARGUMENT);
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parents:
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196 }
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diff changeset
197 System.arraycopy(value, 0, reference, TYPE_OFFSET, TYPE_FIELD_LENGTH);
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198 }
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199
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
200 /**
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
201 * Get the chunk's data.
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parents:
diff changeset
202 */
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parents:
diff changeset
203 byte[] getData() {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
204 int dataLength = getLength();
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
205 if (reference.length < MIN_LENGTH + dataLength) {
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parents:
diff changeset
206 SWT.error (SWT.ERROR_INVALID_RANGE);
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parents:
diff changeset
207 }
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Frank Benoit <benoit@tionex.de>
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diff changeset
208 byte[] data = new byte[dataLength];
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
209 System.arraycopy(reference, DATA_OFFSET, data, 0, dataLength);
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diff changeset
210 return data;
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parents:
diff changeset
211 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
212
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
213 /**
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parents:
diff changeset
214 * Set the chunk's data.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
215 * This method has two side-effects.
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parents:
diff changeset
216 * 1. It will set the length field to be the length
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
217 * of the data array given.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
218 * 2. It will set the CRC field to the computed CRC
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
219 * value of the data array given.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
220 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
221 void setData(byte[] data) {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
222 setLength(data.length);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
223 System.arraycopy(data, 0, reference, DATA_OFFSET, data.length);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
224 setCRC(computeCRC());
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diff changeset
225 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
226
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
227 /**
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parents:
diff changeset
228 * Get the CRC value for the chunk's data.
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parents:
diff changeset
229 * Ensure that the length field has a good
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
230 * value before making this call.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
231 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
232 int getCRC() {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
233 int crcOffset = DATA_OFFSET + getLength();
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
234 return getInt32(crcOffset);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
235 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
236
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
237 /**
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
238 * Set the CRC value for the chunk's data.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
239 * Ensure that the length field has a good
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
240 * value before making this call.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
241 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
242 void setCRC(int value) {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
243 int crcOffset = DATA_OFFSET + getLength();
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
244 setInt32(crcOffset, value);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
245 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
246
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
247 /**
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
248 * Get the chunk's total size including the length, type, and crc fields.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
249 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
250 int getSize() {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
251 return MIN_LENGTH + getLength();
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
252 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
253
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
254 /**
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
255 * Compute the CRC value for the chunk's data. Answer
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
256 * whether this value matches the value stored in the
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
257 * chunk.
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
258 */
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
259 bool checkCRC() {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
260 int crc = computeCRC();
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
261 int storedCRC = getCRC();
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
262 return crc is storedCRC;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
263 }
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
264
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
265 /**
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
266 * Answer the CRC value of chunk's data.
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
267 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
268 int computeCRC() {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
269 int crc = 0xFFFFFFFF;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
270 int start = TYPE_OFFSET;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
271 int stop = DATA_OFFSET + getLength();
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
272 for (int i = start; i < stop; i++) {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
273 int index = (crc ^ reference[i]) & 0xFF;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
274 crc = CRC_TABLE[index] ^ ((crc >> 8) & 0x00FFFFFF);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
275 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
276 return ~crc;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
277 }
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
278
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
279 bool typeMatchesArray(byte[] array) {
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
280 for (int i = 0; i < TYPE_FIELD_LENGTH; i++) {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
281 if (reference[TYPE_OFFSET + i] !is array[i]){
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
282 return false;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
283 }
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
284 }
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
285 return true;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
286 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
287
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
288 bool isCritical() {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
289 char c = cast(char) getTypeBytes()[0];
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
290 return 'A' <= c && c <= 'Z';
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
291 }
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
292
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
293 int getChunkType() {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
294 if (typeMatchesArray(TYPE_IHDR)) return CHUNK_IHDR;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
295 if (typeMatchesArray(TYPE_PLTE)) return CHUNK_PLTE;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
296 if (typeMatchesArray(TYPE_IDAT)) return CHUNK_IDAT;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
297 if (typeMatchesArray(TYPE_IEND)) return CHUNK_IEND;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
298 if (typeMatchesArray(TYPE_tRNS)) return CHUNK_tRNS;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
299 return CHUNK_UNKNOWN;
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
300 }
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
301
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
302 /**
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
303 * Read the next PNG chunk from the input stream given.
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
304 * If unable to read a chunk, return null.
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
305 */
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
306 static PngChunk readNextFromStream(LEDataInputStream stream) {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
307 try {
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
308 int headerLength = LENGTH_FIELD_LENGTH + TYPE_FIELD_LENGTH;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
309 byte[] headerBytes = new byte[headerLength];
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
310 int result = stream.read(headerBytes, 0, headerLength);
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
311 stream.unread(headerBytes);
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
312 if (result !is headerLength) return null;
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
313
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
314 PngChunk tempChunk = new PngChunk(headerBytes);
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Frank Benoit <benoit@tionex.de>
parents:
diff changeset
315
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
316 int chunkLength = tempChunk.getSize();
6dd524f61e62 add dwt win and basic java stuff
Frank Benoit <benoit@tionex.de>
parents:
diff changeset
317 byte[] chunk = new byte[chunkLength];
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318
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319 result = stream.read(chunk, 0, chunkLength);
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320 if (result !is chunkLength) return null;
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321
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322 switch (tempChunk.getChunkType()) {
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323 case CHUNK_IHDR:
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324 return new PngIhdrChunk(chunk);
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325 case CHUNK_PLTE:
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326 return new PngPlteChunk(chunk);
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327 case CHUNK_IDAT:
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328 return new PngIdatChunk(chunk);
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329 case CHUNK_IEND:
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330 return new PngIendChunk(chunk);
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331 case CHUNK_tRNS:
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332 return new PngTrnsChunk(chunk);
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333 default:
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334 return new PngChunk(chunk);
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335 }
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336 } catch (IOException e) {
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337 return null;
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338 }
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339 }
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340
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341 /**
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342 * Answer whether the chunk is a valid PNG chunk.
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343 */
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344 void validate(PngFileReadState readState, PngIhdrChunk headerChunk) {
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345 if (reference.length < MIN_LENGTH) SWT.error(SWT.ERROR_INVALID_IMAGE);
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346
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347 byte[] type = getTypeBytes();
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348
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349 // The third character MUST be upper case.
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350 char c = cast(char) type[2];
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351 if (!('A' <= c && c <= 'Z')) SWT.error(SWT.ERROR_INVALID_IMAGE);
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352
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353 // All characters must be letters.
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354 for (int i = 0; i < TYPE_FIELD_LENGTH; i++) {
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355 c = cast(char) type[i];
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356 if (!(('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z'))) {
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357 SWT.error(SWT.ERROR_INVALID_IMAGE);
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358 }
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359 }
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360
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361 // The stored CRC must match the data's computed CRC.
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362 if (!checkCRC()) SWT.error(SWT.ERROR_INVALID_IMAGE);
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363 }
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364
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365 /**
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366 * Provided so that subclasses can override and add
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367 * data to the toString() call.
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368 */
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369 String contributeToString() {
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370 return "";
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371 }
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372
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373 /**
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374 * Returns a string containing a concise, human-readable
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375 * description of the receiver.
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376 *
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377 * @return a string representation of the event
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378 */
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379 public override String toString() {
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380 String buffer = Format( "{\n\tLength: {}\n\tType: {}{}\n\tCRC: {:X}\n}",
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381 getLength(),
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382 cast(String) getTypeBytes(),
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383 contributeToString(),
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384 getCRC());
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385 return buffer;
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386 }
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387
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388 }