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