reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2007, The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | // Author: cevans@google.com (Chris Evans) |
| 17 | |
| 18 | #include "bmpdecoderhelper.h" |
| 19 | |
| 20 | namespace image_codec { |
| 21 | |
| 22 | static const int kBmpHeaderSize = 14; |
| 23 | static const int kBmpInfoSize = 40; |
| 24 | static const int kBmpOS2InfoSize = 12; |
| 25 | static const int kMaxDim = SHRT_MAX / 2; |
| 26 | |
| 27 | bool BmpDecoderHelper::DecodeImage(const char* p, |
| 28 | int len, |
| 29 | int max_pixels, |
| 30 | BmpDecoderCallback* callback) { |
| 31 | data_ = reinterpret_cast<const uint8*>(p); |
| 32 | pos_ = 0; |
| 33 | len_ = len; |
| 34 | inverted_ = true; |
| 35 | // Parse the header structure. |
| 36 | if (len < kBmpHeaderSize + 4) { |
| 37 | return false; |
| 38 | } |
| 39 | GetShort(); // Signature. |
| 40 | GetInt(); // Size. |
| 41 | GetInt(); // Reserved. |
| 42 | int offset = GetInt(); |
| 43 | // Parse the info structure. |
| 44 | int infoSize = GetInt(); |
| 45 | if (infoSize != kBmpOS2InfoSize && infoSize < kBmpInfoSize) { |
| 46 | return false; |
| 47 | } |
| 48 | int cols = 0; |
| 49 | int comp = 0; |
| 50 | int colLen = 4; |
| 51 | if (infoSize >= kBmpInfoSize) { |
| 52 | if (len < kBmpHeaderSize + kBmpInfoSize) { |
| 53 | return false; |
| 54 | } |
| 55 | width_ = GetInt(); |
| 56 | height_ = GetInt(); |
| 57 | GetShort(); // Planes. |
| 58 | bpp_ = GetShort(); |
| 59 | comp = GetInt(); |
| 60 | GetInt(); // Size. |
| 61 | GetInt(); // XPPM. |
| 62 | GetInt(); // YPPM. |
| 63 | cols = GetInt(); |
| 64 | GetInt(); // Important colours. |
| 65 | } else { |
| 66 | if (len < kBmpHeaderSize + kBmpOS2InfoSize) { |
| 67 | return false; |
| 68 | } |
| 69 | colLen = 3; |
| 70 | width_ = GetShort(); |
| 71 | height_ = GetShort(); |
| 72 | GetShort(); // Planes. |
| 73 | bpp_ = GetShort(); |
| 74 | } |
| 75 | if (height_ < 0) { |
| 76 | height_ = -height_; |
| 77 | inverted_ = false; |
| 78 | } |
| 79 | if (width_ <= 0 || width_ > kMaxDim || height_ <= 0 || height_ > kMaxDim) { |
| 80 | return false; |
| 81 | } |
| 82 | if (width_ * height_ > max_pixels) { |
| 83 | return false; |
| 84 | } |
| 85 | if (cols < 0 || cols > 256) { |
| 86 | return false; |
| 87 | } |
| 88 | // Allocate then read in the colour map. |
| 89 | if (cols == 0 && bpp_ <= 8) { |
| 90 | cols = 1 << bpp_; |
| 91 | } |
| 92 | if (bpp_ <= 8 || cols > 0) { |
| 93 | uint8* colBuf = new uint8[256 * 3]; |
| 94 | memset(colBuf, '\0', 256 * 3); |
| 95 | colTab_.reset(colBuf); |
| 96 | } |
| 97 | if (cols > 0) { |
| 98 | if (pos_ + (cols * colLen) > len_) { |
| 99 | return false; |
| 100 | } |
| 101 | for (int i = 0; i < cols; ++i) { |
| 102 | int base = i * 3; |
| 103 | colTab_[base + 2] = GetByte(); |
| 104 | colTab_[base + 1] = GetByte(); |
| 105 | colTab_[base] = GetByte(); |
| 106 | if (colLen == 4) { |
| 107 | GetByte(); |
| 108 | } |
| 109 | } |
| 110 | } |
| 111 | // Read in the compression data if necessary. |
| 112 | redBits_ = 0x7c00; |
| 113 | greenBits_ = 0x03e0; |
| 114 | blueBits_ = 0x001f; |
| 115 | bool rle = false; |
| 116 | if (comp == 1 || comp == 2) { |
| 117 | rle = true; |
| 118 | } else if (comp == 3) { |
| 119 | if (pos_ + 12 > len_) { |
| 120 | return false; |
| 121 | } |
| 122 | redBits_ = GetInt() & 0xffff; |
| 123 | greenBits_ = GetInt() & 0xffff; |
| 124 | blueBits_ = GetInt() & 0xffff; |
| 125 | } |
| 126 | redShiftRight_ = CalcShiftRight(redBits_); |
| 127 | greenShiftRight_ = CalcShiftRight(greenBits_); |
| 128 | blueShiftRight_ = CalcShiftRight(blueBits_); |
| 129 | redShiftLeft_ = CalcShiftLeft(redBits_); |
| 130 | greenShiftLeft_ = CalcShiftLeft(greenBits_); |
| 131 | blueShiftLeft_ = CalcShiftLeft(blueBits_); |
| 132 | rowPad_ = 0; |
| 133 | pixelPad_ = 0; |
| 134 | int rowLen; |
| 135 | if (bpp_ == 32) { |
| 136 | rowLen = width_ * 4; |
| 137 | pixelPad_ = 1; |
| 138 | } else if (bpp_ == 24) { |
| 139 | rowLen = width_ * 3; |
| 140 | } else if (bpp_ == 16) { |
| 141 | rowLen = width_ * 2; |
| 142 | } else if (bpp_ == 8) { |
| 143 | rowLen = width_; |
| 144 | } else if (bpp_ == 4) { |
| 145 | rowLen = width_ / 2; |
| 146 | if (width_ & 1) { |
| 147 | rowLen++; |
| 148 | } |
| 149 | } else if (bpp_ == 1) { |
| 150 | rowLen = width_ / 8; |
| 151 | if (width_ & 7) { |
| 152 | rowLen++; |
| 153 | } |
| 154 | } else { |
| 155 | return false; |
| 156 | } |
| 157 | // Round the rowLen up to a multiple of 4. |
| 158 | if (rowLen % 4 != 0) { |
| 159 | rowPad_ = 4 - (rowLen % 4); |
| 160 | rowLen += rowPad_; |
| 161 | } |
| 162 | |
| 163 | if (offset > 0 && offset > pos_ && offset < len_) { |
| 164 | pos_ = offset; |
| 165 | } |
| 166 | // Deliberately off-by-one; a load of BMPs seem to have their last byte |
| 167 | // missing. |
| 168 | if (!rle && (pos_ + (rowLen * height_) > len_ + 1)) { |
| 169 | return false; |
| 170 | } |
| 171 | |
| 172 | output_ = callback->SetSize(width_, height_); |
| 173 | if (NULL == output_) { |
| 174 | return true; // meaning we succeeded, but they want us to stop now |
| 175 | } |
| 176 | |
| 177 | if (rle && (bpp_ == 4 || bpp_ == 8)) { |
| 178 | DoRLEDecode(); |
| 179 | } else { |
| 180 | DoStandardDecode(); |
| 181 | } |
| 182 | return true; |
| 183 | } |
| 184 | |
| 185 | void BmpDecoderHelper::DoRLEDecode() { |
| 186 | static const uint8 RLE_ESCAPE = 0; |
| 187 | static const uint8 RLE_EOL = 0; |
| 188 | static const uint8 RLE_EOF = 1; |
| 189 | static const uint8 RLE_DELTA = 2; |
| 190 | int x = 0; |
| 191 | int y = height_ - 1; |
| 192 | while (pos_ < len_ - 1) { |
| 193 | uint8 cmd = GetByte(); |
| 194 | if (cmd != RLE_ESCAPE) { |
| 195 | uint8 pixels = GetByte(); |
| 196 | int num = 0; |
| 197 | uint8 col = pixels; |
| 198 | while (cmd-- && x < width_) { |
| 199 | if (bpp_ == 4) { |
| 200 | if (num & 1) { |
| 201 | col = pixels & 0xf; |
| 202 | } else { |
| 203 | col = pixels >> 4; |
| 204 | } |
| 205 | } |
| 206 | PutPixel(x++, y, col); |
| 207 | num++; |
| 208 | } |
| 209 | } else { |
| 210 | cmd = GetByte(); |
| 211 | if (cmd == RLE_EOF) { |
| 212 | return; |
| 213 | } else if (cmd == RLE_EOL) { |
| 214 | x = 0; |
| 215 | y--; |
| 216 | if (y < 0) { |
| 217 | return; |
| 218 | } |
| 219 | } else if (cmd == RLE_DELTA) { |
| 220 | if (pos_ < len_ - 1) { |
| 221 | uint8 dx = GetByte(); |
| 222 | uint8 dy = GetByte(); |
| 223 | x += dx; |
| 224 | if (x > width_) { |
| 225 | x = width_; |
| 226 | } |
| 227 | y -= dy; |
| 228 | if (y < 0) { |
| 229 | return; |
| 230 | } |
| 231 | } |
| 232 | } else { |
| 233 | int num = 0; |
| 234 | int bytesRead = 0; |
| 235 | uint8 val = 0; |
| 236 | while (cmd-- && pos_ < len_) { |
| 237 | if (bpp_ == 8 || !(num & 1)) { |
| 238 | val = GetByte(); |
| 239 | bytesRead++; |
| 240 | } |
| 241 | uint8 col = val; |
| 242 | if (bpp_ == 4) { |
| 243 | if (num & 1) { |
| 244 | col = col & 0xf; |
| 245 | } else { |
| 246 | col >>= 4; |
| 247 | } |
| 248 | } |
| 249 | if (x < width_) { |
| 250 | PutPixel(x++, y, col); |
| 251 | } |
| 252 | num++; |
| 253 | } |
| 254 | // All pixel runs must be an even number of bytes - skip a byte if we |
| 255 | // read an odd number. |
| 256 | if ((bytesRead & 1) && pos_ < len_) { |
| 257 | GetByte(); |
| 258 | } |
| 259 | } |
| 260 | } |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | void BmpDecoderHelper::PutPixel(int x, int y, uint8 col) { |
| 265 | CHECK(x >= 0 && x < width_); |
| 266 | CHECK(y >= 0 && y < height_); |
| 267 | if (!inverted_) { |
| 268 | y = height_ - (y + 1); |
| 269 | } |
| 270 | |
| 271 | int base = ((y * width_) + x) * 3; |
| 272 | int colBase = col * 3; |
| 273 | output_[base] = colTab_[colBase]; |
| 274 | output_[base + 1] = colTab_[colBase + 1]; |
| 275 | output_[base + 2] = colTab_[colBase + 2]; |
| 276 | } |
| 277 | |
| 278 | void BmpDecoderHelper::DoStandardDecode() { |
| 279 | int row = 0; |
| 280 | uint8 currVal = 0; |
| 281 | for (int h = height_ - 1; h >= 0; h--, row++) { |
| 282 | int realH = h; |
| 283 | if (!inverted_) { |
| 284 | realH = height_ - (h + 1); |
| 285 | } |
| 286 | uint8* line = output_ + (3 * width_ * realH); |
| 287 | for (int w = 0; w < width_; w++) { |
| 288 | if (bpp_ >= 24) { |
| 289 | line[2] = GetByte(); |
| 290 | line[1] = GetByte(); |
| 291 | line[0] = GetByte(); |
| 292 | } else if (bpp_ == 16) { |
| 293 | uint32 val = GetShort(); |
| 294 | line[0] = ((val & redBits_) >> redShiftRight_) << redShiftLeft_; |
| 295 | line[1] = ((val & greenBits_) >> greenShiftRight_) << greenShiftLeft_; |
| 296 | line[2] = ((val & blueBits_) >> blueShiftRight_) << blueShiftLeft_; |
| 297 | } else if (bpp_ <= 8) { |
| 298 | uint8 col; |
| 299 | if (bpp_ == 8) { |
| 300 | col = GetByte(); |
| 301 | } else if (bpp_ == 4) { |
| 302 | if ((w % 2) == 0) { |
| 303 | currVal = GetByte(); |
| 304 | col = currVal >> 4; |
| 305 | } else { |
| 306 | col = currVal & 0xf; |
| 307 | } |
| 308 | } else { |
| 309 | if ((w % 8) == 0) { |
| 310 | currVal = GetByte(); |
| 311 | } |
| 312 | int bit = w & 7; |
| 313 | col = ((currVal >> (7 - bit)) & 1); |
| 314 | } |
| 315 | int base = col * 3; |
| 316 | line[0] = colTab_[base]; |
| 317 | line[1] = colTab_[base + 1]; |
| 318 | line[2] = colTab_[base + 2]; |
| 319 | } |
| 320 | line += 3; |
| 321 | for (int i = 0; i < pixelPad_; ++i) { |
| 322 | GetByte(); |
| 323 | } |
| 324 | } |
| 325 | for (int i = 0; i < rowPad_; ++i) { |
| 326 | GetByte(); |
| 327 | } |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | int BmpDecoderHelper::GetInt() { |
| 332 | uint8 b1 = GetByte(); |
| 333 | uint8 b2 = GetByte(); |
| 334 | uint8 b3 = GetByte(); |
| 335 | uint8 b4 = GetByte(); |
| 336 | return b1 | (b2 << 8) | (b3 << 16) | (b4 << 24); |
| 337 | } |
| 338 | |
| 339 | int BmpDecoderHelper::GetShort() { |
| 340 | uint8 b1 = GetByte(); |
| 341 | uint8 b2 = GetByte(); |
| 342 | return b1 | (b2 << 8); |
| 343 | } |
| 344 | |
| 345 | uint8 BmpDecoderHelper::GetByte() { |
| 346 | CHECK(pos_ >= 0 && pos_ <= len_); |
| 347 | // We deliberately allow this off-by-one access to cater for BMPs with their |
| 348 | // last byte missing. |
| 349 | if (pos_ == len_) { |
| 350 | return 0; |
| 351 | } |
| 352 | return data_[pos_++]; |
| 353 | } |
| 354 | |
| 355 | int BmpDecoderHelper::CalcShiftRight(uint32 mask) { |
| 356 | int ret = 0; |
| 357 | while (mask != 0 && !(mask & 1)) { |
| 358 | mask >>= 1; |
| 359 | ret++; |
| 360 | } |
| 361 | return ret; |
| 362 | } |
| 363 | |
| 364 | int BmpDecoderHelper::CalcShiftLeft(uint32 mask) { |
| 365 | int ret = 0; |
| 366 | while (mask != 0 && !(mask & 1)) { |
| 367 | mask >>= 1; |
| 368 | } |
| 369 | while (mask != 0 && !(mask & 0x80)) { |
| 370 | mask <<= 1; |
| 371 | ret++; |
| 372 | } |
| 373 | return ret; |
| 374 | } |
| 375 | |
| 376 | } // namespace image_codec |